Fruit differentiation, palynology, and systematics in the Scabiosa group of genera and Pseudoscabiosa (Dipsacaceae)

摘要

Fruits of Dipsacaceae are single-seeded, have bristle-shaped calyx segments and are tightly enclosed by four fused bracts forming an epicalyx. Comparative morphological and anatomical studies reveal a great diversity of epicalyx and calyx, often relevant to fruit dispersal. The present contribution deals with the Scabiosa group of genera, the core of the Scabioseae tribe. Most of its taxa develop a diaphragma from a meristem on the inside of the epicalyx. This diaphragma, together with the lower part of the epicalyx encloses the fruit proper, whereas the upper parts form a so-called "epi-diaphragma" (ed) and a +- hyaline corona. Differences of the epicalyx with respect to the size and position of the ed, elaboration of the corona, origin of pits (=foveoles) and other morphological and anatomical specializations can be demonstrated. Together with palynological and karyological data these new facts support an improved concept of relationships and systematics for the taxa studied: Scabiosa sect. Scabiosa and sect. Cyrtostemma are closely related and should be united to form the genus Scabiosa s. str.; Pycnocomon can be maintained as an independent genus, sister to Scabiosa sect. Trochocephalus which then has to be treated as a genus, Lomelosia. In contrast, the following genera have to be included in Lomelosia: Tremastelma as Lomelosia sect. Callistemma, and Scabiosiopsis as part of Lomelosia sect. Lomelosia. Pseudoscabiosa deviates in so many features that it has to be excluded from the redefined Scabioseae s. str.