Floral morphology, development, and CYC2 expression of Malpighiaceae.

(A), Banisteriopsis argyrophylla illustrating the stereotypical New World floral morphology and pattern of CYC2 expression in New World Malpighiaceae (expression shown in grey). (B), Acridocarpus zanzibaricus, Sphedamnocarpus angolensis, and Tristellateia australasiae (from left to right) represent three Old World floral phenotypes that have evolved in parallel from a similar New World-type ancestor. (C–E), Scanning electron micrographs showing the typical orientation of the two dorsal petals at the earliest stage of floral development in the New World Malpighiaceae species Bunchosia glandulifera (C) and Heteropterys sp. (D), and in the Old World species, Tristellateia australasiae (E). (F), Phylogeny depicting relationships of the three focal Old World clades: Acridocarpus, African Sphedamnocarpus, and Tristellateia. Grey lines highlight the radially symmetrical sister groups of Malpighiaceae, Centroplacaceae, and Elatinaceae [20]; black lines highlight Malpighiaceae species with the stereotypical New World floral morphology; red highlights the three Old World clades with parallel floral morphologies that have departed from the New World morphology. For reference, the banner petal of the New World Malpighiaceae is highlighted in yellow (C and D). Dotted lines = initial axis of floral symmetry; solid lines = final axis of floral symmetry; arrows indicate the shift in the axis of symmetry that takes place just before anthesis in New World Malpighiaceae [50]. Scale bars equal 100 μm.