Inter tribal variations of fruit structure among four tribes of the family Compositae
Bidyut Kumar Jana* and Sobhan Kr. Mukherjee
Taxonomy and Biosystematics Laboratory, Department of Botany, University of Kalyani, Kalyani, Nadia, West Bengal (India) Email: *janabidyutkumar@yahoo.com, sobhankr@yahoo.com
ABSTRACT
Variations of fruit structure of six species (Aster albanicus, Carpesium cernuum, Helianthus debilis, Leptorhynchos elongates, Podotheca angustifolia and Zinnia haageana), under four tribes- Astereae, Heliantheae, Inuleae and Gnaphaleae of the family Compositae have been studied to observe the detailed morpho-anatomical features, among them. In all the studied fruits, there are great variations of morpho-anatomical features. Morphologically, special attention has been taken to the shape, size, colour, pappus type, stylopodia, carpopodia of the fruits. Among the studied cypselas, in case of Carpesium cernuum and Helianthus debilis, pappus bristles are absent. In the cypsela of Zinnia haageana, insteade of pappus bristle, awn like structure is present. In the cypsela of Carpesium cernuum, surface is glabrous than the remaining five studied cypselas, where the surface is pubescent. Morphologically, phytomelanin layer is exist in the cypselar wall of Helianthus debilis and Zinnia haageana. As, the two species are belongs to the tribe Heliantheae and phytomelanin layer is an important characteristic features of the tribe Heliantheae. Anatomically, mesocarpic region is well studied than another region of the pericarp due to the greait cellular variations in mesocarpic region. In the cypsela of Aster albanicus, Leptorhynchos elongates and Zinnia haageana, vellicular cavity is exists in the mesocarpic region. In the cypsela of Carpesium cernuum, secretary cavity is present in the mesocarpic region. Among the studied cypselas, testal layer is also interesting. In the cypsela of Leptorhynchos elongates and Podotheca angustifolia, testal layer is made up of U-shaped parenchyma cells. The orientation of cotyledons in relation to the cypselar wall is taxonomically significant.The number of resin ducts in each cotyledon is greatly variable.