Macrograph (A) and SEM images (B–F) of inflorescence (A–B) and successive stages of the early floral development (C–F) in Dialypetalanthus fuscescens. A and B: lateral view. C and E: apical view. D and F: lateral-apical view. A. Inflorescence axis with flowers in bud and at anthesis with calyx lobes, corolla lobes, androecium, and style indicated (resp. light green, red, yellow, and purple arrows). Pedicel of each flower with two opposite, possibly slightly displaced with respect to each other, bracteoles (encircled in dark green). Encircled in white the distal part of the main inflorescence axis and lower, an inflorescence unit. Framed in purple the inferior, bilocular ovary. B. Cymosely branched inflorescence unit with a terminal flower (F); scar of one of its bracteoles (Bo) subtending an inflorescence unit consisting of a developing lateral flower with two bracteoles (dark green arrows), a hairy calyx (light green arrows) and inner flower (blue) with centrally the appearing style (purple arrowhead) surrounded by stamens (yellow arrowhead). C. Flower primordium and two bracteoles. D. First two sepals appearing, opposite to each other and at 90° with respect to the pair of bracteoles. E. Four sepals, two by two, surrounding a flat central floral apex. The most recent pair of sepals opposite the bracteoles. F. Appearance of a first pair of petals, at 90° with respect of the latest developed pair of sepals. The floral axis (red arrow), situated in the centre of a cavity formed by the upwards growth of the bases of the surrounding floral parts. Colour code: blue, developing inner flower–pollen grains; green, calyx/bracteoles; purple, gynoecium; red, corolla; yellow, androecium. Symbols: B, bract; Bo, bracteole; ca, calyx (lobe); cl, colleter; co, corolla (lobe); F, flower.

  Part of: Vrijdaghs A, De Block P, De Toni KLG, Smets E, Robbrecht E (2022) Floral ontogeny links Dialypetalanthus (Condamineeae) with the floral developmental morphology of other Rubiaceae. Plant Ecology and Evolution 155(3): 394-403.