Embriology of Eriocaulon xeranthemum Mart. (Eriocaulaceae)

The development of microsporangium, male and female gametophytes, endosperm, embryo and seed-coat of Eriocaulon xeranthemum Mart, has been studied. The microsporangium wall consists of an epidermis, an endothecium, a middle layer and a glandular tapetum. The endothecium is fibrous. Quadripartition in the microspore mother cells is successive. At shedding the pollen grains are 3-celled and spiraperturate. The female gametophyte is of the Polygonum type. The three antipodal cells give rise to a conspicuous antipodal cyst, which breaks down before fertilization. The endosperm is ab initio nuclear. Both apical and basal cells contribute to the formation of the embryo proper. In the mature seed, the embryo is small with an incipient internal differentiation into cotyledonary and epicotylary sectors. Both integuments contribute to the seed coat. The pericarp is 3-layered, thin-walled and membranous.