Structure and development of seedcoat in Cucurbitaceae.

The paper describes the development and structure of seedcoat in Biswarea tonglensis, Edgaria darjeelingensis, and Herpetospermum pedunculosum. The ovules are anatropous, bitegminal, and crassinucellar; they are horizontally disposed in Biswarea but pendulously in Edgaria and Herpetospermum. The ovular supply is unbranched in Biswarea and Herp etosperumum but ramifies in the lower part of seed in Edgaria. The outer integument alone forms the seedcoat which, at maturity, is differentiated into five zones. The epidermis is heterogeneous consisting of upright cells in all these plants. The hypodermis is sinuate, cells thick-walled and lignified; it is 10 to 14-layered in furrows and 20 or more-layered in ridges in Biswarea, 5 or 6-layered in furrows and 8 to 12-layered in ridges in Edgaria, and 2 or 3-layered in furrows and up to 10-layered in ridges in Herpetospermum. The main sclerenchymatous layer consists of osteosclereids. The seedcoat in all these plants is built on a common pattern and suggests a close relationship among them. A key is proposed to distinguish Biswarea, Edgaria and Herpetospermum from each other using external and internal characters of their seeds. [ABSTRACT FROM AUTHOR]