A Comparative Study of Cypselar Features in Two Species of the Tribe Arctotideae, Asteraceae

Abstract

The family Asteraceae is categorized by the presence of a distinct type of fruit known as cypsela. The present study describes the detailed external and internal features of cypselae from two species within the Berkheya clade, Berkheya multijuga (DC.) Roessler and Berkheya purpurea (DC.) Benth. & Hook.f. ex Mast. The tribe Arctotideae was studied earlier in morphological perspective but the information regarding the cypselae is inadequate. The cypselae were studied with the help of light microscope and scanning electron microscope (SEM). Morphologically, the shape and size of cypselae, colour, pappus structure, hair, surface structure, stylopodia and its structure, carpopodium etc. were found to be important features for distinguishing the species. Anatomically, cellular nature of pericarpic region, number and shapes of ribs and elevations, cuticle features, epicarpic characters, mesocarpic differentiation, vascular trace, crystals, testa, endosperm, embryological details were studied and they are vital for differentiation of taxa. A diagnostic key was constructed for identification of the species. The present work showed a valuable taxonomical significance, on the basis of both morpho-anatomical characters of cypselae the identification and classification of various taxa can be easily performed.