Floral development in Schotia and Cynometra (Leguminosae: Caesalpinioideae: Detarieae)

Abstract

Floral development was compared among several relatively unspecialized taxa in caesalpinioid tribe Detarieae: Cynometra webberi, an undescribed species of Cynometra, and three species of Schotia. These share a relatively unspecialized caesalpinioid flower type with no loss of organs, but some organ suppression. They also share the following characters: relatively small bracteoles in early stages, a circular floral apex, helical sepal initiation, and a nonmedian abaxial position of the first sepal initiated. Floral symmetry is radial. Order of initiation is helical among sepals in all. Order of petal initiation varies: helical in Schotia afra, unidirectional in Schotia brachypetala and S. latifolia, and simultaneous in Cynometra. Stamens are initiated unidirectionally in all except in the outer stamen whorl of Schotia afra, which is helical. Overlap of time of initiation between whorls occurs in S. brachypetala, S. latifolia, and Cynometra. The carpel initiates concurrently with the petals or directly thereafter in all. A tetramerous calyx results from fusion of the two upper (adaxial) sepal primordia. The carpel initiates ovules before marginal closure in both genera. Organ suppression includes one or two petals in Schotia and sometimes one in Cynometra.