Fig. 1.

Phenology and reproductive timeline in two varieties of cowpea. Vertically aligned micrographs in g–u represent corresponding male and female developmental stages within the same floral bud. a Vegetative architecture and leaf morphology of IT97K. b Vegetative architecture and leaf morphology of IT86D. c Mature flower of IT86D; the inset shows floral buds of IT97K. d Mature seeds of IT86D. e Mature seeds of IT97K. f Floral development in IT86D; the numerical register of floral buds corresponds to developmental stages illustrated in g–u. g Dissected floral bud of 2.5 mm in length. h Dissected floral bud of 3 mm in length. i Dissected floral bud of 4 mm in length. j Isolated gynoecia of 3.4 mm in length. k Dissected floral bud of 32 mm in length. l Differentiated microspore mother cells. m A tetrad of microspores. n One-nucleate microspore. o Two-nucleate microspore. p Fully differentiated pollen grain. q Ovule primordium containing an archespore. r Megaspore mother cell. s Megaspore mother cell at the onset of meiosis. t Functional and degenerated megaspores. u Fully differentiated female gametophyte. Arc archespore, CC central cell, DMg degenerating megaspore; EC egg cell, FM functional megaspore, M microspore, MMC megaspore mother cell, PMC pollen mother cell, PN polar nucleus, SC sperm cell, Sy synergid, VN vegetative nucleus. Scale bars a and b = 13 cm (inset = 4 cm); c = 5 mm (inset = 0.5 mm); d, e = 4 mm; f = 8.5 mm; g, h = 0.6 mm; i = 1.2 mm; j = 0.5 mm; k = 2.7 mm; l = 13 μm; m–o = 10 μm; p = 20 μm; q–s = 10 μm; t = 11.5 μm; u = 18 μm