Life history of Tetragonia tetragonioides (Pall.) O. Kuntze

Abstract

Accessory flowers arise from the surface of inferior ovaries in 25 % of the flowers of Tetragonia, suggesting an axial nature of the inferior ovary. The ovary is six to nine-loculed, with a single pendulous ovule in each locule.

The anther is tetrasporangiate. The innermost layer of the four-layered wall constitutes a secretory tapetum with multinucleate cells. Cytokinesis in microspore mother cells is simultaneous and results in tetrahedral or decussate tetrads. The pollen grains are shed at the three-celled stage.

The ovules are bitegminal, crassinucellar, and anacampylotropus. The funiculus is long and bears an obturator of glandular cells. The inner integument forms the micropyle and forms a collar at the distal end. A nucellar cap is present. The nucellus persists in the seed as perisperm.

The archesporium is multicelled, although only a single cell develops. Following meiosis the megaspore mother cell gives rise to a linear row of three or four megaspores, of which only the chalaza1 functions to form an embryo sac of the Polygonum type.

The endosperm is of the Nuclear type and eventually assumes a horseshoe shape. Cell formation is restricted to the micropylar region, the rest remaining nuclear until consumed by the embryo.

The embryogeny is of the Solanad type, and the mature embryo is curved and dicotyledonous.