Ontogeny of the ovule, seed coat and fruit wall ofDicoma tomentosa Cass., Asteraceae
Ovule ontogeny and the structure of seed coat and fruit wall inDicoma tomentosa are described. Ovules are anatropous, unitegmic and tenuinucellate. Integument develops from a group of initials and it is dermal in origin. Ovary wall shows zonal differentiation, as an outer zone and inner zone. Zonal demarcation will be completely obliterated after fertilization. An air space around the endothelium, a common feature in the ovules of the Asteraceae, is absent. At early stage, the integument does not exhibit any demarcation of zones. As the seed develops tannin-like substance accumulates around the cells, fruit is ribbed and hairy. Pappus is plumose and found in two whoels.