Date of Award
Doctor of Philosophy
A scanning electron microscopy survey of mature Cercideae seed anatomy, both internal and external, was combined with a developmental study of Cercideae ovules and immature seeds. Such a survey has not been previously undertaken although several features of Cercideae seed anatomy are cited as being unique among legumes; nor have there been any published studies of megagametogenesis or embryogenesis in Bauhinia or in Cercis canadensis;Daily collections of flowering and fruiting material of Cercis canadensis, collections of six Bauhinia taxa at several stages of flowering and fruiting, and mature seeds from 53 of about 200 Bauhinia species, one of two species of Adenolobus, one of four species of Griffonia, and five of six species of Cercis provided material for this survey which yielded new data on ovular configuration and development, differentiation of ovular vasculature and of macrosclereids, derivation of hilar structures and the radicular lobe or micropylar lens, and on epidermal testa patterns in Cercideae. For example, the deeply pseudocrassinucellate Cercideae ovule has both an epistase and a hypostase. The latter has not been previously reported in this tribe nor has the former been noted in the subtribe Bauhiniinae. Also, comparative anatomical studies of ovule and seed demonstrated that one of the structural features often cited as unique to Cercideae, the micropylar lens, is derived from an intercalary meristem located in the mesotesta contiguous to the radicle and may be equivalent in derivation and location, if not in function, to the papilionoid legume radicular lobe. Anatomical observations and a hypothetical model are presented in support of the proposition that the parenchymatous bridge of tissue extending through the exotesta, at the hilar groove, functions in conjunction with the exotesta as a mechanism for seed desiccation;Common testa epidermal patterns on mature Cercideae seeds are reticulate and foveolate in the subtribe Bauhiniinae and papillose in Cercidinae. These epidermal patterns, and hilar configuration, distinguish between the two Cercideae subtribes and are valuable taxonomic characters.
Digital Repository @ Iowa State University, http://lib.dr.iastate.edu/
Seanna Reilly Rugenstein
Rugenstein, Seanna Reilly, "Comparison of seed and ovule development in representative taxa of the tribe Cercideae (Caesalpinioideae, Leguminosae) " (1983). Retrospective Theses and Dissertations. 8435.