Diacritical features of cypselas in two taxa of the tribe Arctotideae (Compositae)
Bidyut Kumar Jana* and Sobhan Kr. Mukherjee
Taxonomy and Biosystematics Laboratory, Department of Botany, University of Kalyani, Kalyani-741235, Nadia, West Bengal (India) Emails: *janabidyutkumar@yahoo.com, sobhankr@yahoo.com
ABSTRACT
The present paper deals with the morphological and histological features of cypselas in two taxa (Berkheya purpurea and Gazania krebsiana) of the tribe Arctotideae of Compositae. The stable and diacritical morphological features of cypselas are the presence of pappus, surface hair, stylopodium, carpopodium etc. Among the studied cypselas, in the cypsela of Berkheya purpurea; scaly pappus is present whereas in the cypsela of Gazania krebsiana, pappus is serrulate setose type. In both the studied cypselas, surface is pubescent type. Stylopodia are inconspicuously developed, fully immersed in the nectar. In the cypsela of Berkheya purpurea, true carpopodium is absent i.e. presence of pseudocarpopodium whereas in the cypsela of Gazania krebsiana, true carpopodium is present and carpopodial cells are arranged in 3-4 rows. Anatomically, pericarpic zone is clearly differentiated into epicarpic and mesocarpic zone. In the cypsela of Gazania krebsiana, within the mesocarpic region; vellicular cavity is present whereas in other studied cypsela, vellicular cavity is absent. In the cypsela of Berkheya purpurea, testal layer is bi-seriately arranged but in Gazania krebsiana, testal layer is uniseriately arranged, U- shaped and parenchymatous. In both the studied cypselas, endosperm layer is uni-seriately arranged, parenchymatous. An artificial key is made for the easy identification of studied taxa on the basis of morphoanatomical characters of mature cypselas.