Diversity of Cypselar Features in Some Species of the Tribe Heliantheae, Family Compositae

The Heliantheae is morphologically most diverse tribe of the family Compositae, which is also manifested in their cypselar features and proven to be a useful source of various taxonomic treatments. Detailed macro and micro morphological characterization of cypselas of five different taxa namely- Spilanthes acmella, Tithonia diversifolia, Tridax procumbens, Wedelia wallichii, Zinnia elegans were performed. Present analysis revealed a wide range of variations in cypsela surface features such as hair distribution pattern, hair types, phytomelanin deposition pattern, presence or absence of ribs etc. Well marked variations in pappus morphology are noticeable in the present taxa, which certainly could be used in higher level taxonomic decisions. Though the features related to stylopodium and carpopodium are found to be comparatively less variable among the above said taxa. This cypselar overview of the studied taxa could be utilized for affinity study and for betterment of tribal and sub-tribal classification system along with other disciplines of systematic. The tribe Heliantheae is one of the most primitive tribe of the Asteraceae. Morphoanatomical features of cypselas of 5 species belonging to the tribe Heliantheae have been studied for proper characterization of taxa. Based on observed characters, a key is presented for identification of the studied taxa.

Author(s): Sourav Paul and Sobhan Kumar Mukherjee

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