Studies in the embryology ofHeliantheae (Compositae)

The embryology ofLagascea mollis, Zinnia angustifolia andGalinsoga parviflora has been studied. The anther archesporium is hypodermal and consists of a single row of 6–8 cells, there are two layers below the epidermis of the anther and a periplasmodial tapetum. Ripe pollen grains are tricolpate and 3-celled. The ovary contains a single ovule, but in a few cases ofGalinsoga parviflora two ovules have been found. The female archesporium is unicellular, but sometimes more than one archesporial cell occurs inLagascea mollis andZinnia angustifolia. The embryo sac development is of the Polygonum type, the synergids are hooked, antipodal cells show great variation. The endosperm development is cellular inGalinsoga parviflora and peripheral layer persists in the mature seed. The embryo development conforms to the Senecio variation of the Asterad type. The pericarp structure and cmbryological features support the disputed systematic position ofLagascea withinHeliantheae. Part of a Ph.D. thesis, accepted at Andhra University.