Abstract

Background and aims – Amaranthus cruentus, native to Mexico and Guatemala, has significant cultural, medicinal, and ornamental uses and growing agricultural relevance. However, little research has focused on its origin and domestication. To determine its domestication syndrome, we identified a set of domestication-linked traits in cultivated A. cruentus and compared them with its wild ancestor A. hybridus and with A. cruentus accessions from different regions. We assessed whether the domestication syndrome enables us (1) to differentiate between the wild and cultivated species and (2) to determine the level of domestication in populations of A. cruentus from different putative centres of domestication.

Material and methods – Populations of A. cruentus and A. hybridus were sampled from Mexico and Guatemala. Ten morphological traits related to vegetative stage, anthesis, and seed maturation were evaluated to identify patterns linked to domestication. PERMANOVA was used to analyse differences in traits between cultivated and wild populations.

Key results – Basal stem size, plant height, inflorescence length, and seed yield (total mass) differed significantly between A. cruentus and A. hybridus. Amaranthus cruentus had a broader range of seed and inflorescence colours. The Mexican accessions had taller plants, longer inflorescences, and greater seed yield than the Guatemalan.

Conclusion – The selected set of characters unambiguously distinguishes the wild A. hybridus from the cultivated A. cruentus, enables differentiation of domestication levels, suggesting that Mexican accessions are more domesticated than the Guatemalan.

Keywords

Amaranthus hybridus, artificial selection, grain amaranth, Guatemala, Mexico, morphological traits, selection pressure

Introduction

Amaranthaceae sensu lato (s.l.) includes Amaranthaceae sensu stricto (s.s), Chenopodiaceae, and other related genera (APG IV: The Angiosperm Phylogeny Group 2016). Amaranthoideae was formerly classified as a subfamily of Amaranthaceae s.s. (sensu Schinz 1893), but in the present, Amaranthoideae (= Amaranthaceae s.s.) is one of the five subfamilies that comprise Amaranthaceae s.l. (Morales-Briones et al. 2021). However, Amaranthus L. is well preserved in the taxonomic history of Amaranthaceae and appears to be monophyletic (Sandoval-Ortega et al. 2017; Xu et al. 2024). The genus comprises 60–75 species, including the cultivated “grain amaranths” (Iamonico 2015; Wolosik and Markowska 2019; Adhikary et al. 2020): Amaranthus caudatus L., A. cruentus L., and A. hypochondriacus L. (Sauer 1950, 1967).

Grain amaranths have grain-like seeds, that are used in a similar way as the fruits (grains) of Poaceae. Their dry fruits are either indehiscent (utricles) or dehiscent (pyxidia), containing a single seed (Sánchez-del Pino et al. 2025). In the Americas, grain amaranths have been cultivated for thousands of years (Purugganan and Fuller 2011; Purugganan 2019) and, with maize (Zea mays L.) and beans (Phaseolus vulgaris L.), formed part of the staple diet of the Aztecs, Incas, and Mayas (Das 2014; Joshi et al. 2018; Zeece 2020). Although there is consensus that the three grain amaranths evolved from wild A. hybridus L., which is distributed throughout Mexico, Central America, northern South America, and in the Mediterranean region of Europe (Das 2016a), there is less consensus about their domestication process (Sánchez-del Pino et al. 2025). However, despite the recognition of the grain amaranths as Intangible Cultural Heritage by UNESCO, their future in Mexico is uncertain due to its limited cultivation (Hernández-Hernández et al. 2018). Efforts are underway to reestablish the value of the grain amaranths (Curiel 2022).

Domestication of plants

Plant domestication dates back more than 10,000 years (Pickersgill 2016). It is an evolutionary process; a wild species is gradually transformed into a cultivated species via artificial trait selection instead of natural selection (e.g. Blanckaert et al. 2012; Chacón-Sánchez 2018; Gonçalves-Dias et al. 2023). Several categorization systems have been proposed to describe the different degrees of domestication, but the two most widely cited are Clement’s (1999) system, which includes wild, incidentally co-evolved, incipiently domesticated, semi-domesticated, and fully domesticated; and that of Meyer et al. (2012), who reduced the categories to domesticated, semi-domesticated, and undomesticated.

Domestication syndrome

Other authors defined the concept of domestication syndrome as a set of morphological traits that differentiate domesticated plants from their wild ancestors and are usually modifications that resulted from human selection (Harlan 1971; Hammer 1984; Meyer et al. 2012; Denham et al. 2020; Pacheco-Huh et al. 2021). Typical features of a domestication syndrome, often resulting from selection for preferred characteristics include changes to secondary metabolism (e.g. reduced bitter compounds, increased sugars, and pigment changes), plant architecture (e.g. modified branching, stem or inflorescence structure, plant height, apical dominance), leaves (e.g. size, shape, arrangement), and fruits (e.g. increased seed retention, larger seeds/fruits, loss of seed dormancy, fruit/seed colour) (Brenner et al. 2000; Rana et al. 2005; Meyer et al. 2012; Joshi et al. 2018; Purugganan 2019; Denham et al. 2020; Mboujda et al. 2022). Plant species have undergone different degrees of domestication, usually in relation to their economic importance. Some are fully domesticated such as maize, which has large seeds that have lost their dormancy and dispersal capacity, and reduced branching and photoperiod sensitivity (Stetter et al. 2017). Other crops such as lentils, quinoa, sorghum, and grain amaranths apparently have poorly demarcated domestication syndromes (Li and Siddique 2018; Ruth et al. 2021; Chapman et al. 2022).

Domestication of grain amaranths

The domestication syndrome of the grain amaranths is still under debate. Some have noted that traits such as seed size and seed retention are shared with their wild relatives (Sauer 1967; Stetter et al. 2020). Stetter et al. (2017) reported that seed colour in A. caudatus is associated with domestication: most cultivated species have pale seeds, while wild amaranth species have dark brown seeds. These authors also revealed a significant loss of genetic variation in domesticated amaranths, suggesting strong agricultural and cultural selection. Based on domestication traits (inflorescence shape, seed shattering, and seed size), which are shared by both wild and cultivated species in Amaranthaceae, Stetter et al. (2017) suggested that the domestication of amaranths may not fit neatly into the traditional model of domestication for well-established crops, proposed by Hammer (1984). Moreover, the phylogenetic and taxonomic status of the putative ancestors of the grain amaranths, A. hybridus and A. quitensis Kunth, is in question (Kietlinski et al. 2014; Sánchez-del Pino et al. 2025). Stetter et al. (2017) concluded that weak artificial selection for seed colour and a high level of gene flow between A. caudatus and A. quitensis has counteracted the fixation of domestication traits.

Amaranthus cruentus

Amaranthus cruentus is an annual plant native to Mexico and Guatemala but is also currently cultivated in the United States, Argentina, and China (Das 2016a; Wolosik and Markowska 2019). In Mexico, the cultivation of A. cruentus declined notably after the arrival and conquests of the Spaniards, relegating it to an underutilized crop with restricted cultivation and limited economic relevance (Joshi et al. 2018).

Archaeological findings, such as in the Coxcatlán caves of Tehuacán, Mexico, suggest that amaranth was crucial to the Aztec civilization and as such extensively cultivated in Mexico by the 15^th century. The domestication probably began more than 6000 years ago (Joshi et al. 2018; Turner et al. 2021). Sauer (1967: 123) mentioned: “Amaranthus cruentus evidently originated as domesticated grain crop somewhere in southern Mexico or Guatemala, the only region where it is found in aboriginal cultivation within the range of its probable progenitor, Amaranthus hybridus”. He also proposed that each grain amaranth has its own “progenitor” at a different centre of domestication. Although the precise origin of cultivated amaranths remains unclear, A. hybridus has been widely recognised as the most likely ancestor (Kietlinski et al. 2014; Stetter et al. 2020; Gonçalves-Dias et al. 2023).

Amaranthus cruentus produces seeds (pseudo-grains, Sánchez-del Pino et al. 2025) that are consumed like a cereal grain and are of high value (Aguilar et al. 2015; Das 2016b; Adeniji 2018; Manyelo et al. 2020; Araujo-León et al. 2023). The International Union for the Protection of New Varieties of Plants (UPOV 2024) reports 29 varieties of A. cruentus from Mexico, Russia, France, the European Union, among others. The National Plant Germplasm System of the United States Department of Agriculture (USDA) holds 428 accessions of A. cruentus (364 active, 349 available), including “landraces” [sic] from Mexico, Guatemala, the United States, India, and China. Additionally, Kauffman (1992) described “morphological groups” of A. cruentus from Guatemala and Mexico, which are clusters of accessions with distinctive traits resulting from traditional selection and might each represent distinct “landraces” [sic] (National Plant Germplasm System 2025).

Three local races of A. cruentus (Mexican, African, and Guatemalan) have also been described, each with specific “phenological” and phenotypic characteristics generated through artificial selection in diverse cultural contexts (Kauffman 1992; Espitia-Rangel et al. 2010). Kauffman’s (1992) “morphological groups” refer to variation at the accession or “landrace” level, whereas the three local races correspond to broader, geographically structured categories recognised later. These local races illustrate how hybridization and selection have shaped the diversity and adaption of A. cruentus across different regions (Espitia-Rangel 2018).

Aim of the study

Although we introduced features that are associated with the domestication syndrome in plants, only seed colour has consistently been identified as a domestication trait for grain amaranths (Sauer 1967; Stetter et al. 2017, 2020; Sánchez-del Pino et al. 2025). Attempts to define a domestication syndrome for the grain amaranths have mostly described generalities, neglecting that each crop has its own evolutionary history and thus its own domestication syndrome. Martínez-Núñez et al. (2019) proposed a method to use amaranths as model plants based on their life cycle. We propose that observations and measurements of traits at different phenological stages can be used to identify a set of characters that pertain to the domestication syndrome.

Studies to assess morphological traits of cultivated amaranths (e.g. Hauptli and Jain 1978; Sogbohossou and Achigan-Dako 2014; Thapa and Blair 2018) did not systematically evaluate traits that resulted from domestication in any of the proposed domestication centres. Our work is the first comparative morphometric analysis of A. cruentus in its postulated centres of domestication (Mexico and Guatemala) including both wild (A. hybridus) and cultivated accessions. Using populations of A. cruentus from Mexico and Guatemala, we sought to identify a set of characteristics based on measurements of morphological characters at different developmental stages of the plant. We then tested their usefulness, in particular considering Sauer’s (1950, 1967) main hypothesis, by evaluating whether this set of traits can reveal different degrees of domestication in the putative centres of domestication proposed by Sauer. We also formulated the following questions: Can we identify a set of traits that unambiguously separates wild, ancestral A. hybridus from cultivated A. cruentus? Can this set be used to determine the level of domestication in populations from different centres of domestication of A. cruentus?

Material and methods

Plant material

Among the 221 individuals belonging to 60 accessions from Mexico and Guatemala that were used, 54 accessions were Amaranthus cruentus (169 individuals) and six accessions were its wild relative Amaranthus hybridus (52 individuals). Fifty-one accessions of A. cruentus were obtained from the National Plant Germplasm System of the United States Department of Agriculture-Agricultural Research Service (National Plant Germplasm System 2025), and three were collected in situ. Thirty-six accessions are from Mexico and 18 from Guatemala. Material of the wild species A. hybridus is challenging to obtain due to limited representation in seed banks and herbarium collections, and because it is often considered a weed, it has received less attention. The six accessions of A. hybridus were collected in Mexico and served as reference species (voucher information: Suppl. material 1; distribution: Fig. 1). Plant identifications were based on the original sources (seed banks and personal collections). Once the plants were cultivated and reached maturity, the original source was checked using the diagnostic keys developed by Sánchez-del Pino et al. (2019). Herbarium specimens of the collected plants were deposited in CICY and UVAL (Thiers 2025).

Figure 1.

Collection localities of accessions for the Amaranthus species used in this study.

Plant growth conditions

The study was conducted at the Centro de Investigación Científica de Yucatán (CICY) from January to June 2023. Fifteen seeds for each accession (Suppl. material 1) were germinated under controlled conditions in a greenhouse (22–27°C). After 15 days, up to five of the most-developed seedlings of A. cruentus and a maximum of 10 of A. hybridus were transplanted into a terraced area in a randomized block design to minimise the effect of differences in natural light, that could influence plant size. Plants were observed and measured at three stages: vegetative, anthesis, and seed maturation (Fig. 2; Martínez-Núñez et al. 2019). Although amaranths are predominantly autogamous, to prevent cross-pollination between the cultivated and wild species, we covered each inflorescence of both species with a 30 × 38 cm glassine bag during anthesis. In the greenhouse, plants were irrigated every third day throughout their life cycle. No fertilizers were applied. Pest control was implemented only when infestations were observed (for further details, see Xingú-López 2024).

Figure 2.

Plant stages, defined by Martínez-Núñez et al. (2019), of Amaranthus cruentus when morphological traits were measured (“Days post-seeding”), as described by Martínez-Núñez et al. (2019, grey row) and in this study (blue rows). Values with an asterisk are for A. cruentus; those with two asterisks are for A. hybridus.

Assessment of domestication-linked morphological characters

All 221 plants available for the 60 accessions were measured at the vegetative stage (20 days post-seeding), anthesis stage (60 and 150 days post-seeding), and seed maturation (90 and 180 days post-seeding; Fig. 2).

Eight quantitative and two qualitative traits that are associated with domestication syndromes were considered. Quantitative traits were 1) plant height, 2) basal stem diameter, 3) leaf length, 4) leaf width, 5) terminal inflorescence length, 6) duration of the vegetative stage, 7) dry mass of inflorescence, and 8) seed yield (total mass). Qualitative traits were inflorescence and seed colour. Plant height (1) was measured with a standard tape measure using the method of Vazquez et al. (2011) and Ortiz-Torres et al. (2018). Basal stem diameter (2) was measured 5 cm above the ground using a digital micrometre (0–0.25 mm, Fowler, Massachusetts USA) as specified by Reinaudi et al. (2011). Leaf length (3) and width (4) were measured at the vegetative stage and anthesis. Starting at anthesis on, the leaves begin to senesce, then fall. Three to four randomly selected, well-developed leaves were marked to track length and width during both developmental stages. If the marked leaf had abscised, the closest leaf was used. Terminal inflorescence length (5) (from the last foliage leaf to the tip of the inflorescence) was measured at anthesis and seed maturation (Vazquez et al. 2011). Duration of the vegetative stage (6) was based on daily observations until the plant reached anthesis. Dry mass of inflorescences (7) was measured at seed maturation. The inflorescences were harvested individually and dried in a climate-controlled room at 38 ± 1°C and 25–30% relative humidity. After drying under controlled room conditions (approximately 12% relative humidity), seed and dried inflorescences were weighed using a precision balance (220 g/ 0.1 mg, Ohaus Explorer, EX224, USA). Seed yield (total mass) (8) was weighed when seeds were mature. All seeds were removed manually from the inflorescences on one plant and weighed using a precision balance (220 g/ 0.1 mg, Ohaus Explorer, EX224, USA). Values were recorded in grams of total seed per plant.

The qualitative traits were assessed using the guidelines in the “Graphic Handbook for Variety Description in Amaranth (Amaranthus spp.)” by the National Seed Inspection and Certification Service (CP-SNICS 2006).

Statistical analyses

PERMANOVA was used to test for significant differences in values for the morphological traits at each developmental stage between A. cruentus and A. hybridus, and among A. cruentus populations from different regions, because it is a non-parametric approach that does not rely on distributional assumptions, such as normality or homogeneity of variances. This method is particularly useful for analysing complex, high-dimensional datasets or when the assumptions of an ANOVA are not met (Dwivedi et al. 2019; Hamidi et al. 2019), as was the case for our data. Our samples comprised 169 individuals of A. cruentus and 52 of A. hybridus, which might cause a bias when using ANOVA; therefore, the small number of A. hybridus accessions did not influence the outcome of this study results when using PERMANOVA. Moreover, PERMANOVA was used to detect differences between Mexican and Guatemalan accessions of A. cruentus.

Minimum, maximum, and mean values and standard deviations were determined for each trait and compared between A. cruentus and A. hybridus at each of the three developmental stages using PERMANOVA in the R package vegan v.2.6-10 (Oksanen et al. 2025).

Nonmetric multidimensional scaling (NMDS) in the R package vegan v.2.6-10 (Oksanen et al. 2025) was used to visualise the similarity structure among samples of 1) A. cruentus and A. hybridus, 2) Mexican and Guatemalan populations of A. cruentus, in a lower-dimensional space based on the morphological traits at each stage. Pearson’s correlation analysis in R package stats v.4.4.0 (R Core Team 2024) was used to analyse how the traits are correlated within and between both species (Morales Saavedra et al. 2019; Ciccarelli and Bona 2022).

Plant height, basal stem diameter, leaf length and width, terminal inflorescence length, inflorescence dry mass, and seed yield were included in multivariate statistical analyses. Duration of the vegetative stage, inflorescence and seed colour were evaluated as qualitative descriptors and not included in the multivariate tests. The frequency of the occurrence of the qualitative characters was determined in each accession.

Results

Morphometric analyses of wild and cultivated Amaranthus species

Our results revealed substantial morphological differences between the cultivated and wild species in plant height, leaf length and width at the vegetative stage; inflorescence length and duration of the vegetative stage at anthesis; and plant height, dry mass of the inflorescence, and seed yield (total mass) at seed maturation (Table 1). At the vegetative stage, plants of A. cruentus were taller and had larger and wider leaves compared to A. hybridus. The duration of the vegetative stage in A. hybridus was 49 days after transplant, compared to 100 days for A. cruentus. Amaranthus cruentus developed significantly larger inflorescences than A. hybridus. At seed maturation, mean plant height for A. cruentus was significantly greater than for A. hybridus and A. cruentus had substantially greater inflorescence dry mass and seed yield (total mass) compared to A. hybridus.

Table 1.

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Minimum (Min), maximum (Max), and mean ± SD for plant height, basal stem diameter, leaf dimensions, terminal inflorescence length, inflorescence dry mass, and seed yield of assessed Amaranthus species at different growth stage. * d = days until anthesis.

Species name	Stage	Statistic	Plant height (cm)	Basal stem diameter (cm)	Leaf length (cm)	Leaf width (cm)	Duration of vegetative stage (d)*	Terminal inflorescence length (cm)	Inflorescence dry mass (g)	Seed yield (g)
Amaranthus cruentus	Vegetative	Min	2.50	0.11	1.90	0.83	60
		Mean ± SD	16.02 ± 10.30	0.53 ± 0.27	6.08 ± 3.16	3.59 ± 1.95	100
		Max	54.00	1.40	24.30	11.00	150
	Anthesis	Min	42.30	0.50	3.60	1.70		2.00
		Mean ± SD	118.01 ± 35.20	1.58 ± 0.49	14.60 ± 6.88	7.01 ± 5.93		10.74 ± 2.81
		Max	247.00	2.58	53.43	13.66		53.50
	Seed maturation	Min	33.50	0.52				16.00	5.00	1.81
		Mean ± SD	160.40 ± 45.60	1.66 ± 0.62				40.75 ± 11.60	45.7 ± 26.30	12.35 ± 9.49
		Max	262.60	6.00				74.00	119.00	43.54
Amaranthus hybridus	Vegetative	Min	2.40	0.11	1.03	0.47	27
		Mean ± SD	11.00 ± 10.10	0.30 ± 0.20	3.90 ± 2.62	2.17 ± 1.40	49
		Max	35.00	0.85	10.67	6.17	74
	Anthesis	Min	9.50	0.16	1.20	0.73		1.60
		Mean ± SD	59.19 ± 54.9	0.74 ± 0.63	5.90 ± 5.25	2.91 ± 4.31		7.55 ± 1.84
		Max	177.00	2.22	14.83	6.83		22.30
	Seed maturation	Min	18.00	0.66				7.50	7.00	1.76
		Mean ± SD	105.20 ± 66.30	0.97 ± 0.54				30.00 ± 11.60	18.08 ± 26.30	5.28 ± 5.05
		Max	225.00	2.04				69.00	62.00	18.56

The PERMANOVA results (Table 2) showed the greatest differentiation between the two species at anthesis (F = 103.61; p < 0.001). At seed maturation, the differences remained significant (F = 42.049; p < 0.001), but the variance decreased to 20.1%. The vegetative stage had the lowest level of differentiation (F = 30.226; p < 0.001), with only 12.18 % of the variance explained. The NMDS scatter diagram (Fig. 3) illustrates the variation between the two species across the growth stages: the traits of the cultivated species appear more clustered than those of the wild relative.

Figure 3.

NMDS plots of traits. A–C. Amaranthus cruentus (blue dots) and A. hybridus (cyan dots) during different growth stages. A. Vegetative. B. Anthesis. C. Seed maturation. D–F. A. cruentus from Mexico (pink dots) and Guatemala (green dots) at different growth stages. D. Vegetative stage. E. Anthesis. F. Seed maturation.

Table 2.

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PERMANOVA of morphological traits at different growth stages of the two Amaranthus species.

Stage	d.f.	SS	R²	F	Pr(>F)
Vegetative	1	1.95	0.12	30.22	0.001
Anthesis	1	3.76	0.35	103.61	0.001
Seed maturation	1	1.29	0.20	42.04	0.001

Several positive correlations were found between morphological traits of individual plants for the two Amaranthus species at different stages of growth (Table 3), reflecting trait variation across the two species. At the vegetative stage, plant height, stem diameter, and leaf length and width were positively correlated. At anthesis, positive correlations persisted between plant height and leaf length and width. At seed maturation, inflorescence dry mass and seed yield were strongly correlated, and stem diameter was also positively correlated with inflorescence dry mass and seed yield.

Table 3.

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Pearson’s correlation values of traits for the two Amaranthus species during different growth stages.

Stage	Trait	Plant height	Basal stem diameter	Leaf length	Leaf width	Terminal inflorescence length	Inflorescence dry mass	Seed yield
Vegetative	Plant height	1.00	0.89	0.77	0.77
	Basal stem diameter	0.89	1.00	0.80	0.83
	Leaf length	0.77	0.84	1.00	0.76
	Leaf width	0.77	0.31	0.76	1.00
Anthesis	Plant height	1.00	0.55	0.07	0.73	0.13
	Basal stem diameter	0.55	1.00	0.57	0.65	-0.04
	Terminal inflorescence length	0.13	-0.04	-0.001	-0.002	1.00
	Leaf length	0.71	0.57	1.00	0.85	-0.001
	Leaf width	0.72	0.65	0.85	1.00	-0.002
Seed maturation	Plant height	1.00	0.67			0.47	0.46	0.31
	Basal stem diameter	0.67	1.00			0.48	0.63	0.58
	Terminal inflorescence length	0.47	0.48			1.00	0.63	0.56
	Inflorescence dry mass	0.49	0.63			0.63	1.00	0.78
	Seed yield	0.31	0.58			0.56	0.78	1.00

Furthermore, correlations among the morphological traits were examined within each species separately to explore trait interrelationships. Plant height, stem diameter, leaf length, and leaf width were strongly positive correlated at the vegetative stage in A. cruentus and A. hybridus. At anthesis, positive correlations among plant height, leaf length, and leaf width persisted in both species except for stem diameter, which was only positively correlated at this stage for A. cruentus. During the seed maturation stage, positive correlations among plant height, stem diameter, terminal inflorescence length, inflorescence dry mass, and seed mass were present in both species. However, the correlation between terminal inflorescence length and seed mass was comparatively weaker in A. hybridus (Suppl. material 2).

At anthesis, inflorescences of A. cruentus had a wider range of colours (shades of green, purple, pink, and red) than those of A. hybridus, which are green (Fig. 4). However, the most common inflorescence colour in A. cruentus was green (Fig. 5A).

Figure 4.

Colour variations in inflorescences of the two Amaranthus species studied. A–E. A. cruentus. F. A. hybridus.

Figure 5.

Frequency distribution of (A) inflorescence colours at anthesis and (B) mature seed colours for Amaranthus cruentus and A. hybridus.

Mature seeds of A. cruentus exhibited a wide range of colours (white to yellow, brown, and black), but white was most common. Seeds of A. hybridus were always black (Figs 5B, 6).

Figure 6.

Colour variations in seeds of Amaranthus cruentus (A–H), and A. hybridus (I–J).

Traits of A. cruentus accessions from Mexico and Guatemala

The comparative morphometric analysis of the traits at three growth stages showed significant differences between the accessions from Mexico and Guatemala (Table 4) in leaf length and width at the vegetative stage; plant height, basal stem diameter, leaf length, leaf width, and terminal inflorescence length during anthesis; and plant height, basal stem diameter, terminal inflorescence length, inflorescence dry mass, and seed yield at seed maturation stage. During the vegetative stage, Mexican accessions had larger and wider leaves than the Guatemalan (Table 4). At anthesis, Mexican accessions had taller plants, thicker basal stems, larger leaves, and considerably longer terminal inflorescences (43 vs 37 cm in Guatemalan accessions; Table 4). At seed maturation, Mexican accessions consistently produced taller plants (262.6 vs 213.0 cm in the Guatemalan accessions; Table 4), thicker basal stems, and longer and heavier inflorescences, resulting in greater dry biomass (51 vs 37 g, respectively; Table 4). The Mexican accessions also had higher seed yields (mean 13.5 g, max 43.5 g) compared to the Guatemalan accessions.

Table 4.

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Minimum (Min), maximum (Max), and mean ± SD for plant height, basal stem diameter, leaf dimensions, terminal inflorescence length, inflorescence dry mass, and seed yield of assessed Amaranthus cruentus from Mexico and Guatemala at different growth stages.

Species	Stage	Statistic	Plant height (cm)	Basal stem diameter (cm)	Leaf length (cm)	Leaf width (cm)	Terminal inflorescence length (cm)	Inflorescence dry mass (g)	Seed yield (g)
Mexico	Vegetative	Min	6.00	0.11	1.91	1.06
		Mean ± SD	16.00 ± 8.08	0.55 ± 0.23	6.28 ± 3.11	3.76 ± 1.79
		Max	46.00	1.29	24.30	11.00
	Anthesis	Min	42.30	0.50	3.60	1.80	2.00
		Mean ± SD	121.90 ± 38.00	1.64 ± 0.50	14.68 ± 6.69	7.58 ± 3.04	10.52 ± 7.35
		Max	247.00	2.57	53.43	13.66	53.50
	Seed maturation	Min	36.00	0.62			16.00	12.00	1.81
		Mean ± SD	163.80 ± 48.90	1.76 ± 0.66			42.88 ± 12.00	50.92 ± 27.00	13.55 ± 10.40
		Max	262.60	2.14			74.00	119.00	43.54
Guatemala	Vegetative	Min	2.50	0.10	2.00	0.83
		Mean ± SD	16.18 ± 13.40	0.50 ± 0.33	5.74 ± 3.23	3.30 ± 2.20
		Max	54.00	1.40	13.80	10.29
	Anthesis	Min	42.50	0.53	4.47	1.70	3.70
		Mean ± SD	125.00 ± 28.50	1.45 ± 0.45	13.93 ± 4.12	6.04 ± 1.99	11.10 ± 5.91
		Max	180.00	2.55	22.60	11.57	28.00
	Seed maturation	Min	33.50	0.52			18.50	5.00	1.82
		Mean ± SD	155.20 ± 38.80	1.51 ± 0.50			37.21 ± 9.84	36.48 ± 22.40	10.22 ± 7.28
		Max	213.00	2.60			58.30	116.00	35.89

The PERMANOVA analysis (Table 5) comparing the Mexican and Guatemalan accessions of A. cruentus revealed significant differences during the vegetative stage (F = 7.98; p < 0.004) and seed maturation (F = 5.57; p < 0.012), but not during anthesis (F = 2.39; p > 0.1). In the NMDS ordination analysis (Fig. 3), individuals of A. cruentus from Mexico and Guatemala during the vegetative stage were not clearly separated by country (Fig. 3D). In contrast, at anthesis (Fig. 3E) and seed maturation (Fig. 3F), individuals were more dispersed in the ordination space, reflecting increased morphological variation within the species.

Table 5.

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PERMANOVA of morphological traits at different growth stages of Amaranthus cruentus from Mexico and Guatemala.

Stage	d.f.	SS	R²	F	Pr(>F)
Vegetative	1	0.43	0.04	7.97	0.004
Anthesis	1	0.04	0.01	2.38	0.100
Seed maturation	1	0.12	0.03	5.57	0.012

Several positive correlations among the accessions of A. cruentus were observed (Table 6): at the vegetative stage, plant height, stem diameter, and leaf length and width; at anthesis, plant height, stem diameter and leaf length and width; at seed maturation inflorescence dry mass with seed yield, terminal inflorescence length and stem diameter with inflorescence dry mass and seed yield.

Table 6.

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Pearson’s correlation values of traits for Amaranthus cruentus from Mexico and Guatemala at different growth stages.

Stage	Trait	Plant height	Basal stem diameter	Leaf length	Leaf width	Terminal inflorescence length	Inflorescence dry mass	Seed yield
Vegetative	Plant height	1.00	0.89	0.71	0.75
	Basal stem diameter	0.89	1.00	0.75	0.80
	Leaf length	0.71	0.75	1.00	0.71
	Leaf width	0.75	0.80	0.71	1.00
Anthesis	Plant height	1.00	0.68	0.58	0.61	-0.06
	Basal stem diameter	0.68	1.00	0.58	0.69	-0.18
	Terminal inflorescence length	-0.06	-0.18	-0.16	-0.16	1.00
	Leaf length	0.58	0-58	1.00	0.79	-0.16
	Leaf width	0.61	0.69	0.79	1.00	-0.16
Seed maturation	Plant height	1.00	0.59			0.39	0.41	0.19
	Basal stem diameter	0.59	1.00			0.41	0.56	0.52
	Terminal inflorescence length	0.39	0.41			1.00	0.64	0.85
	Inflorescence dry mass	0.41	0.56			0.64	100	0.78
	Seed yield	0.19	0.52			0.58	0.78	1.00

Discussion

Justification for the set of domestication-linked characters

Plant height, leaf length and width

According to Joshi et al. (2018), features of plant architecture such as plant height and leaf length and width distinguish cultivated amaranths species from their wild relatives. Moreover, in the grain amaranths, seed yield is positively correlated with increasing plant height (Masaku et al. 2018). Rana et al. (2005) identified plant height and leaf size in A. hypochondriacus as characters that influence its agricultural performance. Humans probably selected for leaf dimensions as well as plant height in Amaranthus, but even if they did not, cultivated plants typically are taller and have larger leaves than their wild ancestors (Pérez-Pérez et al. 2010; Xiao et al. 2014; Milla and Matesanz 2017; Sánchez-del Pino et al. 2025). For example, the leaves and shoot tips of A. cruentus are also harvested for consumption before the inflorescence appear (Mapes et al. 1996; Sooriyapathirana et al. 2021), which may have led to selection of plants with larger leaves and taller plants. According to Brenner et al. (2000), vegetable amaranth cultivars, often appreciated locally for their high protein content and remarkable leaf production, are extensively grown throughout Africa, Asia, the Caribbean, and Central America.

Basal stem diameter

Stem diameter is a vital agronomic trait related to robustness of plants (Li et al. 2020). Wider stems are usually associated with healthier plants, tolerance to environmental stress, and structural strength and stability. Thick, sturdy stems can support the heavy seed loads that are produced on the large terminal inflorescence (Mapes et al. 1996; Sooriyapathirana et al. 2021; De Melo et al. 2023; Fabris et al. 2023) and are particularly relevant in reducing lodging (permanent bending/breaking of crop stem), which can severely impact seed yield.

Terminal inflorescence length, inflorescence colour, inflorescence dry mass, and duration of vegetative stage

In cereals and several other crops including amaranths (Rana et al. 2005; Joshi et al. 2018), inflorescence length is correlated positively with seed yield (Boden et al. 2015; Feng et al. 2017; Nirubana et al. 2021; Manugade et al. 2023). In addition, inflorescence length is associated with efficient harvesting, genetic diversity, and adaptation to environmental conditions (Joshi et al. 2018). Also, inflorescence length and seed production are positively correlated. In amaranths, crop management, breeding, cultural preferences and agricultural performance affect the inflorescence colour, which also serves as a visual indicator of maturity, and may be associated with stress tolerance and pest resistance (Joshi et al. 2018). In cereal crops, inflorescence architecture determines both the quantity and the quality of seed production (Feng et al. 2017; Yamburenko et al. 2017). Also in amaranths, inflorescence dry mass is closely associated with seed yield, so it is an indicator of overall plant health and vigour (Joshi et al. 2018). Inflorescence biomass can be considered as a consequence of selection conditions that promote vigorous growth (Zhang and Yuan 2014; Studer et al. 2017). Artificial selection on different traits influences the time from germination to anthesis (Feng et al. 2017) (called “flowering time” by Joshi et al. 2018: 1813 vs “duration of vegetative stage” here). According to Joshi et al. (2018), in grain amaranths, flowering time is correlated with factors such as species characteristics, environmental conditions, and management practices.

Seed yield and colour

In many cultivated crops, seed yield is 50% higher than in their wild relatives (Rehman et al. 2014; Preece et al. 2017; Thakur and Prasad 2021). Grain amaranths such as A. hypochondriacus have higher seed yields, reflecting selection for enhanced grain productivity (Brenner et al. 2000; El Gendy et al. 2017). In Amaranthus, seed colour appears to also be a trait explicitly linked to domestication (Stetter et al. 2020). In A. cruentus, seed colour varies from light to dark, a pattern also observed in other crops (Sultan et al. 2014). Such variability suggests that seed colour is influenced by consumer preferences, leading to differences in uses. Not only is seed colour an aesthetic trait, but it is also associated with perceived quality attributes (e.g. flavour and nutritional content; Stetter et al. 2017; Abtahi et al. 2022).

In summary, the selected domestication-linked characters in this study are justified and supported by the literature. The traits plant height, leaf length and width, basal stem diameter, terminal inflorescence length, inflorescence colour, inflorescence dry mass, duration of vegetative stage, seed yield and colour have been highlighted in studies on amaranths and other crops, particularly due to their relevance to agronomic performance, reproductive output, and human selection during domestication.

Distinguishing A. hybridus and A. cruentus using the set of domestication-linked characters

In the NMDS plot of the 10 characters, the points for A. hybridus are in a very dispersed cloud, whereas the points for A. cruentus are concentrated inside the larger cloud for A. hybridus (Fig. 3). The higher number of A. hybridus points reflects our sampling strategy, in which up to 10 individuals were selected per accession, so that traits for 52 individuals were measured throughout their life cycle. This finding suggests that there is an overall distinction between the two species. Amaranthus hybridus and A. cruentus share some characters, which should not be surprising since A. hybridus is considered to be the ancestor of A. cruentus. However, several domestication-linked characters distinguish A. cruentus from A. hybridus (Sánchez-del Pino et al. 2025: fig. 8I–K). According to our results (Table 2), the vegetative stage exhibits the lowest level of differentiation between the two species, suggesting that in the earlier developmental stages there is little or no morphological distinctions between the two species studied. In A. cruentus, the vegetative phase appears to retain ancestral traits as observed for other crops (Jisha et al. 2011).

Plant height and stem diameter

From anthesis on, A. cruentus tended to have a larger basal stem diameter and plants than A. hybridus, which fits the common tendencies seen in other crops (Niklas and Enquist 2002; Herron et al. 2020; Kaur et al. 2023) (Table 1). By the time seeds are maturing, the thick, sturdy stems can support the heavy seed loads on the large terminal inflorescences, indicating more robust vegetative growth in the cultivated species. Our results are consistent with the findings of Maughan et al. (2011) and Akin-Idowu et al. (2016) in A. cruentus. The taller height of A. cruentus at all growth stages allows the plant to compete with weeds to maximize light interception for photosynthesis, as found in other domesticated crops (Cunniff et al. 2014; Peiffer et al. 2014). Brenner et al. (2000) and Spehar (2003) suggested a correlation between the height of A. cruentus and its photoperiod insensitivity.

Leaf length and width

At anthesis, the leaves of A. cruentus tended to be larger than on A. hybridus (Table 2). Modifications of the leaves of A. cruentus later in development may help maximize light absorbance and photosynthesis (Sooriyapathirana et al. 2021). Mapes et al. (1996) suggested humans selected for leaf size when they consumed the leaves. Indeed, the leaves of A. hybridus are eaten, mostly in Guatemala and Africa and those of A. cruentus in Mexico (Turreira-García et al. 2015; Cáceres and Cruz 2019; Gresta et al. 2020; Mapes et al. 2023). However, in our opinion, the larger leaf size is rather a side effect of selection for taller plants with larger inflorescences because leaves for eating are harvested before anthesis. For A. cruentus, measurements at seed maturation were not possible due to leaf senescence and shedding. As A. cruentus plants approached seed maturity, leaves began to senesce earlier than on A. hybridus (Table 1). These findings are consistent with those of Thapa et al. (2021), who also observed earlier leaf senescence in cultivated grain species of Amaranthus.

Terminal inflorescence length, inflorescence colour, inflorescence dry mass, and duration of the vegetative stage

Amaranthus cruentus tended to develop larger terminal inflorescences and smaller lateral inflorescences in contrast to A. hybridus (Table 1). These results concur with those of Mapes et al. (1996), Sogbohossou and Achigan-Dako (2014), El Gendy et al. (2017), and Thapa and Blair (2018). Denham et al. (2020) also suggested that selection for taller, more erect plants leads to fewer lateral branches. Such a growth pattern is common in many others crops (Doust 2007; Fuller 2010). Distal inflorescences facilitate seed retention and reduce premature seed dispersal during maturation (Adhikari et al. 2022). According to Thapa and Blair (2018), cultivated amaranths exhibit greater diversity in inflorescence traits, particularly in pigmentation. Our findings are consistent with this observation (Fig. 4), with A. cruentus displaying a broader range of colours compared to A. hybridus. This variation may reflect artificial selection for aesthetic features in cultivated species for commercial production (Altman et al. 2022). Our results for inflorescence dry mass (Table 1) are consistent with the findings of Gomes et al. (2024). According to Thapa and Blair (2018), the higher inflorescence dry mass of cultivated amaranths, particularly at higher planting densities, likely reflects an indirect consequence of artificial selection for larger or more productive inflorescences, rather than direct artificial selection for dry mass. In contrast, in wild amaranths inflorescence size and dry mass depend strongly on local growth conditions. According to our observations, the duration of the vegetative stage is shorter in A. hybridus than in A. cruentus (Table 1). This result agrees with those of Espitia-Rangel (2018) and Waselkov et al. (2020), who mentioned that early flowering in many wild species is a distinctive adaptation to environmental factors such as temperature and photoperiod.

Seed yield and seed colour

Our results showed that A. cruentus produced more seeds than A. hybridus, which is related to artificial selection on seed production and domestication (Mapes et al. 1996). A similarly increased seed production is also observed in several cereal crops such as rice (Oryza sativa L.), wheat (Triticum aestivum L.), sorghum (Sorghum bicolor (L.) Moench), and barley (Hordeum vulgare L.) (Garibaldi et al. 2021; He et al. 2023; Alam and Purugganan 2024). We observed pale seeds and dark seeds in A. cruentus (Figs 5B, 6), as also reported by Hauptli and Jain (1978), Espitia-Rangel et al. (2010), and Jacques et al. (2021). The other two grain amaranths have pale seeds, suggesting that A. cruentus is less domesticated. Other possible explanations are 1) hybridization between A. cruentus and A. hybridus because both species coexist in the same regions; 2) artificial selection in A. cruentus was not only concentrated on higher seed yield, but also on producing quality ornamentals or vegetables (Sauer 1967; Espitia-Rangel et al. 2010; Srivastava 2015).

The set domestication-linked characters on A. cruentus from different centres of domestication

At anthesis and seed maturation, the NMDS analysis (Fig. 7) showed a more dispersed cloud for the overall set of characters in A. cruentus from Mexico than in A. cruentus from Guatemala, suggesting that the two populations are distinct. At the vegetative stage, both populations are dispersed without distinction, which is not surprising considering that the relevant characters for domestication are mostly characters linked to the inflorescence or characters that are realised late in the life cycle. It should be noted that the Mexican dataset includes more accessions than the Guatemalan one, which may be related to the lower collection rates in Guatemala compared with Mexico (Ivonne Sánchez-del Pino pers. comm.).

Plant height and stem diameter

From the vegetative stage onward, stem diameters are larger for plants from Mexican accessions compared to the Guatemalan (Tables 4, 5).

Leaf length and width

Mexican A. cruentus tended to have longer and wider leaves at the vegetative stage. Guatemalan plants displayed smaller leaves on average, which may reflect either local environmental adaptations or less intensive selection (Espitia-Rangel et al. 2010, 2020).

Terminal inflorescence length, inflorescence colour, inflorescences dry mass, and duration of vegetative stage

At anthesis, Mexican accessions of A. cruentus exhibit longer terminal inflorescences compared to Guatemalan accessions, as observed by Espitia-Rangel (2018). According to this author, Mexican accessions typically have lateral inflorescences on the upper stem with a single dominant apical inflorescence, whereas Guatemalan accessions develop one smaller, inflorescence. Mexican accessions of A. cruentus display greater chromatic diversity, ranging from green to deep purple, consistent with reports by Kauffman (1992) and Espitia-Rangel et al. (2010, 2020), and may reflect higher levels of genetic diversity and divergent selection pressures, potentially linked to cultural preferences or local uses. Mexican accessions of A. cruentus at seed maturation have greater inflorescence dry mass compared to Guatemalan accessions, which is indicative of artificial selection for grain yield in Mexico (Thapa and Blair 2018; Gomes et al. 2024). The duration of the vegetative stage of Mexican accessions of A. cruentus is within the flowering range for most A. cruentus plants reported (e.g. Baturaygil and Schmid 2022; Uriarte Ortiz et al. 2023). In comparison, Guatemalan accessions had a longer vegetative stage. According to Baturaygil and Schmid (2022), the duration of the vegetative stage in grain amaranths and wild relatives varies in temperate conditions, where accessions from regions with longer day lengths tend to flower earlier, demonstrating the species’ sensitivity to photoperiod changes.

Seed yield and colour

At seed maturation, Mexican accessions of A. cruentus had greater seed yield compared to Guatemalan accessions (Tables 4, 5), which is consistent with higher seed use in Mexico (Mapes 1997; Espitia-Rangel et al. 2010, 2018; Casini and La Rocca 2014). Seed colour in A. cruentus varied from black to white, as already reported by Espitia-Rangel et al. (2010, 2020). Seed colour also differed notably between populations: white seeds predominated in the Mexican accessions, reflecting historical selection for white seeds, in contrast to Guatemalan accessions. These patterns are consistent with previous reports (Mapes 1997; Espitia-Rangel et al. 2010, 2018, 2020) and suggest that differential human selection and cultural practices have played a key role in shaping seed traits across populations. Aguilera-Cauich et al. (2020) also found that the morphological traits of plants from Guatemala suggest there was less human intervention. The artificial selection of traits for different purposes in A. cruentus led to the development of local varieties in Guatemala and Mexico and to different degrees of domestication.

Conclusion

We identified a set of domestication-linked characters for A. cruentus, based on measurements of morphological variables at different developmental stages. This set was tested as a domestication syndrome in populations of A. cruentus from Mexico and Guatemala in the context of Sauer’s (1967) main domestication hypothesis.

Based on our results, we can answer our first question (determining a set of traits to separate unambiguously wild, ancestral A. hybridus and cultivated A. cruentus). An overall analysis of 10 selected characters linked to domestication separates A. hybridus from A. cruentus. The six most-diverse characters can be considered together as a domestication syndrome for A. cruentus: basal stem diameter, plant height, inflorescence length, inflorescence colour, seed colour, and seed yield.

With regard to our second question (using the set of characters to determine levels of domestication in populations from different centres of domestication of A. cruentus), applying the set of characters to A. cruentus from two different centres of domestication allowed us to determine a difference in domestication level. In addition, when looking at individual characters, reproductive traits such as the length of the terminal inflorescence, dry inflorescence mass, and seed yield proved to be the most discriminative and relevant for domestication. Moreover, differences in seed colour in the populations of A. cruentus from Mexico and Guatemala suggest that the Mexican population is more domesticated than the Guatemalan population. Alternatively, the differences can be explained by artificial selection for different purposes or by hybridization between A. cruentus and A. hybridus.

Acknowledgements

We thank the National Plant Germplasm System of the United States Department of Agriculture (USDA) for providing plant material. David Brenner’s generous collaboration and review of the manuscript have been fundamental to our research. We are indebted to Edlin J. Guerra Castro (Escuela Nacional de Estudios Superiores, UNAM, Yucatán, México) for his contributions to PERMANOVA analyses. We thank Alejandra Paz (UNAM), Diana Mayreb (UNAM), Eduardo Gutiérrez (UADY), Jesús Ucan (ITSM), and Tabatha Cerna (UNAM) for their technical support. We are grateful to Allison Jazmín Téllez-Sánchez for preparing the illustrations for Fig. 3. We also thank CONAHCYT/SECIHTI for support under project FORDECYT-PRONACES-15319/2020 and CONAHCYT/SECIHTI for PhD scholarship 857164. We also are grateful to the anonymous reviewers and subject editor Elmar Robbrecht for their constructive feedback.

References

Abtahi M, Mirlohi A, Sharif-Moghaddam N, Ataii E (2022) Revealing seed color variation and their possible association with yield and quality traits in a diversity panel of flax (Linum usitatissimum L.). Frontiers in Plant Science 13: 1038079. https://doi.org/10.3389/fpls.2022.1038079

Adeniji OT (2018) Genetic variation and heritability for foliage yield and yield component traits in edible Amaranthus cruentus L. genotypes. Bangladesh Journal of Agricultural Research 43(3): 513–524. https://doi.org/10.3329/bjar.v43i3.38397

Adhikary D, Khatri-Chhetri U, Slaski J (2020) Amaranth: an ancient and high-quality wholesome crop. In: Waisundara VY (Ed.)Nutritional Value of Amaranth. IntechOpen, 111–142. https://doi.org/10.5772/intechopen.88093

Adhikari P, Joshi LP, Ayer DK, Tiwari KR (2022) Agromorphological diversity and disease assessment of grain amaranth in Lamjung, Nepal. Advances in Agriculture 2022: 1–12. https://doi.org/10.1155/2022/8969390

Aguilar EG, Albarracín GJ, Uñates MA, Piola HD, Camiña JM, Escudero NL (2015) Evaluation of the nutritional quality of the grain protein of new amaranths varieties. Plant Foods for Human Nutrition 70(1): 21–26. https://doi.org/10.1007/s11130-014-0456-3

Aguilera-Cauich E, Solís-Fernández KZ, Ibarra-Morales A, Cifuentes-Velásquez R, Sánchez-del Pino I (2020) Amaranto: distribución y diversidad morfológica del recurso genético en partes de la región Maya (sureste de México, Guatemala y Honduras). Acta Botanica Mexicana 128: e1738. https://doi.org/10.21829/abm128.2021.1738

Akin-Idowu PE, Gbadegesin MA, Orkpeh U, Ibitoye DO, Odunola OA (2016) Characterization of grain amaranth (Amaranthus spp.) germplasm in South West Nigeria using morphological, nutritional, and random amplified polymorphic DNA (RAPD) analysis. Resources 5(1): 6. https://doi.org/10.3390/resources5010006

Alam O, Purugganan MD (2024) Domestication and the evolution of crops: variable syndromes, complex genetic architectures, and ecological entanglements. The Plant Cell 36(5): 1227–1241. https://doi.org/10.1093/plcell/koae013

Altman A, Shennan S, Odling-Smee J (2022) Ornamental plant domestication by aesthetics-driven human cultural niche construction. Trends in Plant Science 27(2): 124–138. https://doi.org/10.1016/j.tplants.2021.09.004

Araujo-León JA, Aguilar-Hernández V, Sánchez-del Pino I, Brito-Argáez L, Peraza-Sánchez SR, Xingú-López A, Ortiz-Andrade R (2023) Analysis of red amaranth (Amaranthus cruentus L.) betalains by LC-MS. Journal of the Mexican Chemical Society 67(3): 227–239. https://doi.org/10.29356/jmcs.v67i3.1967

Baturaygil A, Schmid K (2022) Characterization of flowering time in genebank accessions of grain amaranths and their wild relatives reveals signatures of domestication and local adaptation. Agronomy 12(2): 505. https://doi.org/10.3390/agronomy12020505

Blanckaert I, Paredes-Flores M, Espinosa-García FJ, Piñero D, Lira R (2012) Ethnobotanical, morphological, phytochemical, and molecular evidence for the incipient domestication of Epazote (Chenopodium ambrosioides L.: Chenopodiaceae) in a semi-arid region of Mexico. Genetic Resources and Crop Evolution 59(4): 557–573. https://doi.org/10.1007/s10722-011-9704-7

Boden SA, Cavanagh C, Cullis BR, Ramm K, Greenwood J, Jean Finnegan E, Trevaskis B, Swain SM (2015) Ppd-1 is a key regulator of inflorescence architecture and paired spikelet development in wheat. Nature Plants 1(2): 14016. https://doi.org/10.1038/nplants.2014.16

Brenner DM, Baltensperger DD, Kulakow PA, Lehmann JW, Myers RL, Slabbert MM, Sleugh BB (2000) Genetic resources and breeding of Amaranthus. In: Janick J (Ed.) Plant Breeding Reviews, Vol. 19. Wiley, New York, 227–285. https://doi.org/10.1002/9780470650172.ch7

Cáceres A, Cruz SM (2019) Edible seeds, leaves and flowers as Maya Super Foods: Function and composition. International Journal of Phytocosmetics and Natural Ingredients 6(1): 2–2. https://doi.org/10.15171/ijpni.2019.02

Casini P, La Rocca F (2014) Amaranthus cruentus L. is suitable for cultivation in central Italy: field evaluation and response to plant densities. Italian Journal of Agronomy 9(4): 166–175. https://doi.org/10.4081/ija.2014.602

Chacón-Sánchez MI (2018) The domestication syndrome in Phaseolus crop plants: a review of two key domestication traits. In: Pontarotti P (Ed.) Origin and Evolution of Biodiversity. Springer International Publishing, Cham, 37–59. https://doi.org/10.1007/978-3-319-95954-2_3

Chapman MA, He Y, Zhou M (2022) Beyond a reference genome: pangenomes and population genomics of underutilized and orphan crops for future food and nutrition security. New Phytologist 234(5): 1583–1597. https://doi.org/10.1111/nph.18021

Ciccarelli D, Bona C (2022) Exploring the functional strategies adopted by coastal plants along an ecological gradient using morpho-functional traits. Estuaries and Coasts 45: 114–120. https://doi.org/10.1007/s12237-021-00945-y

Clement CR (1999) 1492 and the loss of Amazonian crop genetic resources. I. The relation between domestication and human population decline. Economic Botany 53(2): 188–202. https://doi.org/10.1007/BF02866498

CP-SNICS (2006) Manual Gráfico para la Descripción Varietal en Amaranto (Amaranthus spp). Colegio de Postgraduados-Servicio Nacional de Inspección y Certificación de Semillas, Montecillos.

Cunniff J, Wilkinson S, Charles M, Jones G, Rees M, Osborne CP (2014) Functional traits differ between cereal crop progenitors and other wild grasses gathered in the neolithic fertile crescent. PLoS ONE 9(1): e87586. https://doi.org/10.1371/journal.pone.0087586

Curiel C (2022) El amaranto como alimento indígena: producción de patrimonio y activismo alimentario. Encartes 5(10): 203–233. https://doi.org/10.29340/en.v5n10.243

Das S (2014) Domestication, phylogeny, and taxonomic delimitation in underutilized grain Amaranthus (Amaranthaceae) - a status review. Feddes Repertorium 123(4): 273–282. https://doi.org/10.1002/fedr.201200017

Das S (2016a) Amaranthus: a Promising Crop of Future. Springer, Singapore. https://doi.org/10.1007/978-981-10-1469-7

Das S (2016b) Pseudocereals: an efficient food supplement. In: Rengel Z (Ed.) Amaranthus: a Promising Crop of the Future. Springer, Singapore, 5–11. https://doi.org/10.1007/978-981-10-1469-7_2

De Melo RE, De Abreu ED, Barbosa ED, Da Silva AEB, Da Silva CB, De Souza Júnior JH, Silva Neto CP, Da Silva JR (2023) Humic substances extracted from organic compounds and their influence on the morphophysiological characteristics of tomato seedlings. DELOS: Desarrollo Local Sostenible 16(43): 734–751. https://doi.org/10.55905/rdelosv16.n43-016

Denham T, Barton H, Castillo C, Crowther A, Dotte-Sarout E, Florin SA, Pritchard J, Barron A, Zhang, Y, Fuller DQ (2020) The domestication syndrome in vegetatively propagated field crops. Annals of Botany 125(4): 581–597. https://doi.org/10.1093/aob/mcz212

Doust A (2007) Architectural evolution and its implications for domestication in grasses. Annals of Botany 100(5): 941–950. https://doi.org/10.1093/aob/mcm040

Dwivedi P, Sucre E, Turnblom EC, Harrison RB (2019) Investigating relationships between nutrient concentrations, stem sinuosity, and tree improvement in Douglas-fir stands in western Washington. Forests 10(7): 541. https://doi.org/10.3390/f10070541

El Gendy ANG, Tavarini S, Conte G, Pistelli L, Hendawy SF, Omer EA, Angelini LG (2017) Yield and qualitative characterisation of seeds of Amaranthus hypochondriacus L. and Amaranthus cruentus L. grown in central Italy. Italian Journal of Agronomy 13(1): 63–73. https://doi.org/10.4081/ija.2017.993

Espitia-Rangel E (2018) Breeding of grain amaranth. In: Paredes-López O (Eds) Amaranth Biology, Chemistry, and Technology. CRC Press, Boca Raton, 23–38.

Espitia-Rangel E, Mapes-Sánchez C, Escobedo-López D, De la O-Olán M, Rivas-Valencia P, Martínez-Trejo G, Cortés-Espinoza L, Hernández-Casillas JM (2010) Conservación y Uso de los Recursos Genéticos de Amaranto en México. INIFAP, Centro de Investigación Regional Centro, Celaya, Guanajuato, México.

Espitia-Rangel E, Escobedo-López D, Núñez-Colín CA, Aguilar-Delgado MJ, Rivas-Valencia P, Sesma-Hernández LF (2020) Confirmación de razas geográficas de amaranto (Amaranthus spp.) por análisis discriminante canónico. Agrociencia 54(7): 927–937. https://doi.org/10.47163/agrociencia.v54i7.2243

Fabris DN, Gomes EP, Silva CJ, Flumignan DL, Mello KAM, Sanches AC (2023) Effect of water supply and sowing dates on corn yield of hybrids grown during offseason. Engenharia Agrícola 43(1): e20210020. https://doi.org/10.1590/1809-4430-Eng.Agric.v43n1e20210020/2023

Feng N, Song G, Guan J, Chen K, Jia M, Huang D, Wu J, Zhang L, Kong X, Geng S, Liu J, Li A, Mao L (2017) Transcriptome profiling of wheat inflorescence development from spikelet initiation to floral patterning identified stage-specific regulatory genes. Plant Physiology 174(3): 1779–1794. https://doi.org/10.1104/pp.17.00310

Fuller DQ (2010) An emerging paradigm shift in the origins of agriculture. General Anthropology 17(2): 1–12. https://doi.org/10.1111/j.1939-3466.2010.00010.x

Garibaldi LA, Aizen MA, Sáez A, Gleiser G, Strelin MM, Harder LD (2021) The influences of progenitor filtering, domestication selection and the boundaries of nature on the domestication of grain crops. Functional Ecology 35(9): 1998–2011. https://doi.org/10.1111/1365-2435.13819

Gomes VEV, Mesquita RO, Nunes LR, Innecco R (2024) Agronomic performance of grain amaranth in the semi-arid region as a function of the planting arrangement. Revista Caatinga 37: e11913. https://doi.org/10.1590/1983-21252024v3711913rc

Gonçalves-Dias J, Singh A, Graf C, Stetter MG (2023) Genetic incompatibilities and evolutionary rescue by wild relatives shaped grain amaranth domestication. Molecular Biology and Evolution 40(8): msad177. https://doi.org/10.1093/molbev/msad177

Gresta F, Meineri G, Oteri M, Santonoceto C, Lo Presti V, Costale A, Chiofalo B (2020) Productive and qualitative traits of Amaranthus cruentus L.: an unconventional healthy ingredient in animal feed. Animals 10(8): 1–18. https://doi.org/10.3390/ani10081428

Hamidi B, Wallace K, Vasu C, Alekseyenko AV (2019) W*_d-test: robust distance-based multivariate analysis of variance. Microbiome 7(1): 51. https://doi.org/10.1186/s40168-019-0659-9

Hammer K (1984) Das Domestikationssyndrom. Die Kulturpflanze 32(1): 11–34. https://doi.org/10.1007/BF02098682

Harlan JR (1971) Agricultural origins: centers and noncenters. Science 174(4008): 468–474. https://doi.org/10.1126/science.174.4008.468

Hauptli H, Jain SK (1978) Biosystematics and agronomic potential of some weedy and cultivated amaranths. Theoretical and Applied Genetics 52(4): 177–185. https://doi.org/10.1007/BF00282575

He T, Angessa TT, Li C (2023) Pleiotropy structures plant height and seed weight scaling in barley despite long history of domestication and breeding selection. Plant Phenomics 5: 0015. https://doi.org/10.34133/plantphenomics.0015

Hernández-Hernández BR, Santiago Ibañez DP, Enrique A, Velasco M, Carrasco CC, Maldonado JR (2018) Empresas sociales rurales, estrategia de desarrollo sustentable y conservacion del patrimonio cultural inmaterial. Caso: “amaranto (Amaranthus spp) de mesoamerica”. Revista Mexicana de Agronegocios 42: 956–967. https://doi.org/10.22004/ag.econ.275187

Herron SA, Rubin MJ, Ciotir C, Crews TE, Van Tassel DL, Miller AJ (2020) Comparative analysis of early life stage traits in annual and perennial Phaseolus crops and their wild relatives. Frontiers in Plant Science 11: 34. https://doi.org/10.3389/fpls.2020.00034

Iamonico D (2015) Taxonomic revision of the genus Amaranthus (Amaranthaceae) in Italy. Phytotaxa 199(1): 1–84. https://doi.org/10.11646/phytotaxa.199.1.1

Jacques O, Mariam K, Boukare K, Boureima S, Zakaria K, Kando Pauline B (2021) Identification and agronomic performance of species of the genus Amaranthus grown in Burkina Faso. International Journal of Applied Agricultural Sciences 7(2): 102. https://doi.org/10.11648/j.ijaas.20210702.15

Jisha MS, Beevy SS, Nair GM (2011) Species relationship in the genus Cucumis L. revealed by crossability, chromosome pairing and seed protein electrophoresis. The Nucleus 54(1): 35–38. https://doi.org/10.1007/s13237-011-0026-0

Joshi DC, Sood S, Hosahatti R, Kant L, Pattanayak A, Kumar A, Yadav D, Stetter MG (2018) From zero to hero: the past, present and future of grain amaranth breeding. Theoretical and Applied Genetics 131(9): 1807–1823. https://doi.org/10.1007/s00122-018-3138-y

Kauffman CS (1992) The status of grain amaranth for the 1990s. Food Reviews International 8(1): 165–185. https://doi.org/10.1080/87559129209540935

Kaur J, Pathak M, Pathak D (2023) Development and characterization of F1 hybrids involving cultivated and related species of okra. Vegetable Science 50(01): 73–77. https://doi.org/10.61180/vegsci.2023.v50.i1.10

Kietlinski KD, Jimenez F, Jellen EN, Maughan PJ, Smith SM, Pratt DB (2014) Relationships between the weedy Amaranthus hybridus (Amaranthaceae) and the grain amaranths. Crop Science 54(1): 220–228. https://doi.org/10.2135/cropsci2013.03.0173

Li P, Tian Q, Peng Z, Fang Z, Qing Y, Zhao H (2020) Main agronomic traits and photosynthetic pathways of potatoes. International Journal of Design & Nature and Ecodynamics 15(3): 431–439. https://doi.org/10.18280/ijdne.150317

Li X, Siddique KHM (2018) Rediscovering hidden treasures of neglected and underutilized species for zero hunger in Asia. Food and Agriculture Organization of the United Nations, Bangkok, 2018.

Manugade RP, Hamane GM, Bhalekar NB (2023) Evaluation of different genotypes of quinoa (Chenopodium quinoa Willd.) for yield and yield contributing parameters. International Journal of Plant & Soil Science 35(19): 783–787. https://doi.org/10.9734/ijpss/2023/v35i193611

Manyelo TG, Sebola NA, Hassan ZM, Mabelebele M (2020) Characterization of the phenolic compounds in different plant parts of Amaranthus cruentus grown under cultivated conditions. Molecules 25(18): 4273. https://doi.org/10.3390/molecules25184273

Mapes C, Caballero J, Espitia E, Bye RA (1996) Morphophysiological variation in some Mexican species of vegetable Amaranthus: evolutionary tendencies under domestication. Genetic Resources and Crop Evolution 43(3): 283–290. https://doi.org/10.1007/BF00123280

Mapes C, Mujica-Sánchez Á, Cortés-Zárraga L (2023) Amaranthus crassipes Schltdl Amaranthus cruentus L. Amaranthus dubius Mart. ex Thell Amaranthus fimbriatus (Torr.) Benth. ex S. Watson Amaranthus graecizans L. Amaranthus hybridus L. Amaranthus hypochondriacus L. Amaranthus palmeri S. Watson Amaranthus polygonoides L. Amaranthus powellii S. Amaranthus retroflexus L. Amaranthus spinosus L. Amaranthus viridis L. Amaranthus watsonii Standl Amaranthaceae. In: Casas A, Blancas Vázquez JJ (Eds) Ethnobotany of the Mountain Regions of Mexico. Ethnobotany of Mountain Regions. Springer, Cham, 1049–1065. https://doi.org/10.1007/978-3-030-99357-3_27

Mapes E (1997) Etnobotánica del “quintonil” conocimiento, uso y manejo de Amaranthus spp. en Mexico. PhD Thesis, Universidad Nacional Autónoma de México, México.

Martínez-Núñez M, Ruiz-Rivas M, Vera-Hernández PF, Bernal-Muñoz R, Luna-Suárez S, Rosas-Cárdenas FF (2019) The phenological growth stages of different amaranth species grown in restricted spaces based in BBCH code. South African Journal of Botany 124: 436–443. https://doi.org/10.1016/j.sajb.2019.05.035

Masaku M, Githiri S, Onyango C, Masinde P (2018) Genotypic variation of green gram accessions in the arid and semi-arid lands of Kenya. Journal of Agriculture and Ecology Research International 15(2): 1–15. https://doi.org/10.9734/jaeri/2018/43169

Maughan PJ, Smith SM, Fairbanks DJ, Jellen EN (2011) Development, characterization, and linkage mapping of single nucleotide polymorphisms in the grain amaranths (Amaranthus sp.). The Plant Genome 4(1): 92–101. https://doi.org/10.3835/plantgenome2010.12.0027

Mboujda FMM, Avana-Tientcheu M-L, Momo ST, Ntongme AM, Vaissayre V, Azandi LN, Dussert S, Womeni H, Onana J-M, Sonké B, Tankou C, Duminil J (2022) Domestication syndrome in Dacryodes edulis (Burseraceae): comparison of morphological and biochemical traits between wild and cultivated populations. Plants 11(19): 2496. https://doi.org/10.3390/plants11192496

Meyer RS, DuVal AE, Jensen HR (2012) Patterns and processes in crop domestication: an historical review and quantitative analysis of 203 global food crops. New Phytologist 196(1): 29–48. https://doi.org/10.1111/j.1469-8137.2012.04253.x

Milla R, Matesanz S (2017) Growing larger with domestication: a matter of physiology, morphology or allocation? Plant Biology 19(3): 475–483. https://doi.org/10.1111/plb.12545

Morales-Briones DF, Kadereit G, Tefarikis DT, Moore MJ, Smith SA, Brockington SF, Timoneda A, Yim WC, Cushman JC, Yang Y (2021) Disentangling sources of gene tree discordance in phylogenomic data sets: testing ancient hybridizations in Amaranthaceae s.l. Systematic Biology 70(2): 219–235. https://doi.org/10.1093/sysbio/syaa066

Morales Saavedra JC, Rodríguez Zaragoza FA, Cabrera Toledo D, Sánchez Hernández CV, Vargas-Ponce O (2019) Agromorphological characterization of wild and weedy populations of Physalis angulata in Mexico. Scientia Horticulturae 246: 86–94. https://doi.org/10.1016/j.scienta.2018.10.055

National Plant Germplasm System (2025) GRIN-Global. National Plant Germplasm System, United States Department of Agriculture-Agricultural Research Service. https://npgsweb.ars-grin.gov/gringlobal/search [accessed 08.01.2026]

Niklas KJ, Enquist BJ (2002) On the vegetative biomass partitioning of seed plant leaves, stems, and roots. The American Naturalist 159(5): 482–497. https://doi.org/10.1086/339459

Nirubana V, Ravikesavan R, Ganesamurthy K (2021) Evaluation of underutilized kodo Millet (Paspalum scrobiculatum L.) accessions using morphological and quality traits. Indian Journal of Agricultural Research 55(3): 303–309. https://doi.org/10.18805/IJARe.A-5462

Oksanen JF et al. (2025) vegan: community ecology package. https://doi.org/10.32614/CRAN.package.vegan

Ortiz-Torres E, Argumedo-Macías A, García-Perea H, Meza-Varela R, Bernal-Muñoz R, Taboada-Gaytán OR (2018) Grain yield and expansion volume of improved varieties of Amaranth for high valleys of Puebla. Revista Fitotecnia Mexicana 41(3): 291–300. https://doi.org/10.35196/rfm.2018.3.291-300

Pacheco-Huh J, Carmona D, Dzib G, Chávez-Pesqueira M (2021) Mutualistic and antagonistic interactions differ in wild and domesticated papaya (Carica papaya) in its centre of origin. Plant Biology 23(2): 250–258. https://doi.org/10.1111/plb.13214

Peiffer JA, Romay MC, Gore MA, Flint-Garcia SA, Zhang Z, Millard MJ, Gardner CAC, McMullen MD, Holland JB, Bradbury PJ, Buckler ES (2014) The genetic architecture of maize height. Genetics 196(4) 1337–1356. https://doi.org/10.1534/genetics.113.159152

Pérez-Pérez JM, Esteve-Bruna D, Micol JL (2010) QTL analysis of leaf architecture. Journal of Plant Research 123(1): 15–23. https://doi.org/10.1007/s10265-009-0267-z

Pickersgill B (2016) Domestication of plants in Mesoamerica: an archaeological review with some ethnobotanical interpretations. In: Lira R, Casas A, Blancas J (Eds) Ethnobotany of Mexico. Ethnobiology. Springer, New York, 207–231. https://doi.org/10.1007/978-1-4614-6669-7_9

Preece C, Livarda A, Christin P-A, Wallace M, Martin G, Charles M, Jones G, Rees M, Osborne CP (2017) How did the domestication of fertile crescent grain crops increase their yields? Functional Ecology 31(2): 387–397. https://doi.org/10.1111/1365-2435.12760

Purugganan MD (2019) Evolutionary insights into the nature of plant domestication. Current Biology 29(14): R705–R714. https://doi.org/10.1016/j.cub.2019.05.053

Purugganan MD, Fuller DQ (2011) Archaeological data reveal slow rates of evolution during plant domestication. Evolution 65(1): 171–183. https://doi.org/10.1111/j.1558-5646.2010.01093.x

R Core Team (2024) R: a language and environment for statistical computing. R Foundation for Statistical Computing, Vienna, Austria. https://www.r-project.org/ [accessed 08.01.2026]

Rana JC, Yadav SK, Mandal S, Yadav S (2005) Genetic divergence in grain amaranth (Amaranthus hypochondriacus L.) germplasm. Indian Journal of Genetics and Plant Breeding 65(2): 65–99.

Rehman HU, Nawaz Q, Basra SMA, Afzal I, Yasmeen A, ul-Hassan F (2014) Seed priming influence on early crop growth, phenological development and yield performance of linola (Linum usitatissimum L.). Journal of Integrative Agriculture 13(5): 990–996. https://doi.org/10.1016/S2095-3119(13)60521-3

Reinaudi NB, Repollo R, Janovská D, Frier J, Martín de Troiani R (2011) Evaluation of Amaranth (Amaranthus sp.) Genotypes for Production in the Area of the Faculty of Agriculture, Universidad de la Pampa, Argentina. Universidad de Oriente Press; Revista Científica UDO Agrícola 11: 50–57. http://hdl.handle.net/11336/20397 [accessed 29.01.2026]

Ruth ON, Unathi K, Nomali N, Chinsamy M (2021) Underutilization versus nutritional-nutraceutical potential of the amaranthus food plant: a mini-review. Applied Sciences (Switzerland) 11(15): 6879. https://doi.org/10.3390/app11156879

Sánchez-del Pino I, Dorantes-Euan A, Ibarra-Morales A (2019) First record of invasive and agricultural weed Amaranthus palmeri (Amaranthaceae) for the Peninsula of Yucatan flora and an updated record of Amaranthus diversity in the region. Botanical Sciences 97(3): 433–446. https://doi.org/10.17129/botsci.2189

Sánchez-del Pino I, Vrijdaghs A, Jiménez-Rojas MI, Araujo-León JA, Aguilar-Hernández V, Xingú-López A, Peraza-Sánchez SR (2025) The current state of our knowledge of the domestication and evolution of the grain amaranths: a critical standpoint. [Corrected proofs]. Annals of Botany: mcaf250. https://doi.org/10.1093/aob/mcaf250

Sandoval-Ortega MH, Siqueiros-Delgado ME, Sosa-Ramírez J, Cerros-Tlatilpa R (2017) Amaranthaceae (Caryophyllales) richness and distribution in the state of Aguascalientes, Mexico. Botanical Sciences 95(2): 203–220. https://doi.org/10.17129/botsci.909

Sauer JD (1950) The grain amaranths: a survey of their history and classification. Annals of the Missouri Botanical Garden 37(4): 561. https://doi.org/10.2307/2394403

Sauer JD (1967) The grain amaranths and their relatives: a revised taxonomic and geographic survey. Annals of the Missouri Botanical Garden 54(2) 103–137. https://doi.org/10.2307/2394998

Schinz H (1893) Amaranthaceae. In: Engler A, Prantl K (Eds) Die Natürlichen Pflanzenfamilien, Vol. 3. Leipzig, Engelmann, 91–118.

Sogbohossou OED, Achigan-Dako EG (2014) Phenetic differentiation and use-type delimitation in Amaranthus spp. from worldwide origins. Scientia Horticulturae 178: 31–42. https://doi.org/10.1016/j.scienta.2014.08.003

Sooriyapathirana SDSS, Ranaweera LT, Jayarathne HSM, Gayathree THI, Rathnayake PGRG, Karunarathne SI, Thilakarathne SMNK, Salih R, Weebadde CK, Weebadde CP (2021) Photosynthetic phenomics of field- and greenhouse-grown amaranths vs. sensory and species delimits. Plant Phenomics 2021: 2539380. https://doi.org/10.34133/2021/2539380

Spehar CR (2003) Diferenças morfológicas entre Amaranthus cruentus, cv. BRS Alegria, e as plantas daninhas A. hybridus, A. retroflexus, A. viridis e A. spinosus. Planta Daninha 21(3): 481–485. https://doi.org/10.1590/S0100-83582003000300017

Srivastava R (2015) Assessment of morphological diversity of selected Amaranthus species. Journal of Global Biosciences 4(8): 3044–3058.

Stetter MG, Müller T, Schmid KJ (2017) Genomic and phenotypic evidence for an incomplete domestication of South American grain amaranth (Amaranthus caudatus). Molecular Ecology 26(3): 871–886. https://doi.org/10.1111/mec.13974

Stetter MG, Vidal-Villarejo M, Schmid KJ (2020) Parallel seed color adaptation during multiple domestication attempts of an ancient new world grain. Molecular Biology and Evolution 37(5): 1407–1419. https://doi.org/10.1093/molbev/msz304

Studer AJ, Wang H, Doebley JF (2017) Selection during maize domestication targeted a gene network controlling plant and inflorescence architecture. Genetics 207(2): 755–765. https://doi.org/10.1534/genetics.117.300071

Sultan SM, Dar SA, Dand SA, Sivaraj N (2014) Diversity of common bean in Jammu and Kashmir, India: a DIVAgeographic information system and cluster analysis. Journal of Applied and Natural Science 6(1): 226–233. https://doi.org/10.31018/jans.v6i1.406

Thakur O, Prasad R (2021) Increased seed size mediated by Cyamopsis tetragonoloba big seeds like silencing is positively co-related to galactomannan content, phytochemical biosynthesis, and anti-diabetic potential of guar. [Preprint]. Research Square. https://doi.org/10.21203/rs.3.rs-306592/v1

Thapa R, Blair MW (2018) Morphological assessment of cultivated and wild amaranth species diversity. Agronomy 8(11): 272. https://doi.org/10.3390/agronomy8110272

Thapa R, Edward M, Blair MW (2021) Relationship of cultivated grain amaranth species and wild relative accessions. Genes 12: 1849. https://doi: 10.3390/genes12121849

The Angiosperm Phylogeny Group (2016) An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants: APG IV. Botanical Journal of the Linnean Society 181: 1–20. https://doi.org/10.1111/boj.12385

Thiers B (2025) Index herbariorum: a global directory of public herbaria and associated staff. New York Botanical Garden’s Virtual Herbarium. https://sweetgum.nybg.org/ih/ [accessed 08.01.2026]

Turner MI, Adams KR, Berkebile JN. Dockter AR (2021) Ancient grains: new evidence for ancestral Puebloan use of domesticated amaranth. American Antiquity 86(4): 815–832. https://doi.org/10.1017/aaq.2021.57

Turreira-García N, Theilade I, Meilby H, Sørensen M (2015) Wild edible plant knowledge, distribution and transmission: a case study of the Achí Mayans of Guatemala. Journal of Ethnobiology and Ethnomedicine 11(1): 52. https://doi.org/10.1186/s13002-015-0024-4

UPOV (2024) PLUTO Plant Variety Database. https://www.upov.int/pluto/en/index.html [accessed 25.09.2025]

Uriarte Ortiz RB, Esquivel-Quezada JL, Lacayo-Romero ML, Jarquín-Pascua MC (2023) Evaluación de variables de crecimiento vegetativo de amaranto (Amaranthus cruentus L.) variedad Amaranteca en el Centro de Investigación en Biotecnología, Universidad Nacional Autónoma de Nicaragua, Managua. Revista Torreón Universitario 12(34): 140–148. https://doi.org/10.5377/rtu.v12i34.16379

Vazquez ML, Espitia Rangel E, Carballo Carballo A, Zepeda Bautista R, Vaquera Huerta H, Córdova Téllez L (2011) Fertilización y densidad de plantas en variedades de amaranto (Amaranthus hypochondriacus L.). Revista Mexicana de Ciencias Agrícolas 2: 855–866. https://doi.org/10.29312/remexca.v2i6.1566

Waselkov KE, Regenold ND, Lum RC, Olsen KM (2020) Agricultural adaptation in the native North American weed waterhemp, Amaranthus tuberculatus (Amaranthaceae). PLoS ONE 15(9): e0238861. https://doi.org/10.1371/journal.pone.0238861

Wolosik K, Markowska A (2019) Amaranthus cruentus taxonomy, botanical description, and review of its seed chemical composition. Natural Product Communications 14(5). https://doi.org/10.1177/1934578X19844141

Xiao D, Wang H, Basnet RK, Zhao J, Lin K, Hou X, Bonnema G (2014) Genetic dissection of leaf development in Brassica rapa using a genetical genomics approach. Plant Physiology 164(3): 1309–1325. https://doi.org/10.1104/pp.113.227348

Xingú-López A (2024) Plagas y enfermedades asociadas al cultivo de amaranto en Yucatán. In: Sánchez del Pino I, Vergara Yoisura S (Eds) Xtes: las Delicias Mayas del Amaranto. First edition. Centro de Investigación Científica de Yucatán, A.C, Mérida, Yucatán, Mexico, 59–63.

Xu H, Guo Y, Xia M, Yu J, Chi X, Han Y, Li X, Zhang F (2024) An updated phylogeny and adaptive evolution within Amaranthaceae s.l. inferred from multiple phylogenomic datasets. Ecology and Evolution 14(7): e70013. https://doi.org/10.1002/ece3.70013

Yamburenko MV, Kieber JJ, Schaller GE (2017) Dynamic patterns of expression for genes regulating cytokinin metabolism and signaling during rice inflorescence development. PLoS ONE 2(4): e0176060. https://doi.org/10.1371/journal.pone.0176060

Zeece M (2020) Food systems and future directions. In: Zeece M (Ed.) Introduction to the Chemistry of Food. Academic Press, London, 345–397. https://doi.org/10.1016/B978-0-12-809434-1.00009-8

Zhang D, Yuan Z (2014) Molecular control of grass inflorescence development. Annual Review of Plant Biology 65(1): 553–578. https://doi.org/10.1146/annurev-arplant-050213-040104

Supplementary materials

Supplementary material 1

Voucher information and geographic origin of Amaranthus cruentus L. and A. hybridus L. accessions included in this study, indicating accession or voucher number, species, country, state or department of origin, source or herbarium, and geographic coordinates (latitude and longitude).

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Supplementary material 2

Pearson’s correlation coefficients among morphological traits of Amaranthus cruentus (Table S1) and A. hybridus (Table S2) across different growth stages (vegetative, anthesis, and seed maturation). Correlations were estimated for plant height, stem diameter, leaf length, leaf width, terminal inflorescence length, inflorescence dry mass, and seed mass.

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