Cypselas Diversity as Novel Taxonomic Marker in the Tribe Astereae (Family Asteraceae)

Despite the second largest tribe of the family Asteraceae and immense importance of morphology of cypsela for taxonomic delimitation at tribe level, no work has been done in this direction in the tribe Astereae. In order to evaluate taxonomic implication of cypselas features, diversity of morpho-anatomical features has been carried out in the tribe Astereae. Detail macro as well as micro-morphology and anatomy of cypselas of nine taxa including two species of Aster, two species of Conyza and one species each of Erigeron, Grindelia, Kalimeris, Solidago and Vittadinia of the tribe Astereae (Family Asteraceae) have been examined using Light Microscope. Experiments showed that surface characteristics like distribution arrangement, hair type, ribs and their number, pappus diversity and presence and absence of wing were taxonomically more important features in comparison to colour, size and shape of cypsela. Among anatomical features, mesocarpic characters like type of tissue (whether parenchymatous or sclerenchymatous), their distribution pattern, and nature of testal layer were found to be significant for the tribe Astereae. Finally, involving all these cypselas features an artificial key to the studied species is constructed. The key based on morpho-anatomical fearures could be used as reference key to identify taxa of the tribe Astereae solely based on its cypsela in absence of their flowering stage.