SCHOENENBERGER, JUERG* AND PETER K. ENDRESS. Institute of Systematic Botany, University of Zurich, Zollikerstrasse 107, CH-8008 Zurich, Switzerland.. - Floral structure and development in Thunbergioideae s.l. (Acanthaceae).
Floral structure and development of Thunbergia,
Pseudocalyx and Mendoncia, (Thunbergioideae s.l.,
Acanthaceae) were comparatively studied. Morphology and architecture
of the flowers are highly diverse. Mainly based on differences in
fruit characters, Thunbergioideae s.l. traditionally was subdivided
into two subfamilies (Lindau 1895) or even split into two separate
families (Bremekamp 1953). Study of floral development (especially of
gynoecium) shows that differences in morphology arise only relatively
late during ontogeny. The bauplan of the flowers is uniform within the
subfamily. Study of the elaborate anthetic floral organs reveal
further details that connect the two traditional subfamilies (e.g.,
lack of endothecial cell layer; poricidal opening of anthers;
lignified, unicellular bristles on thecae). Thus, floral structure and
development of Thunbergia, Pseudocalyx and
Mendoncia indicate that these genera form a natural group.
Key words: development, flowers, Mendoncia, morphology, Pseudocalyx, Thunbergia