Structure and development of fruits and seeds of weed species of Euphorbiaceae

Abstract

Euphorbiaceae s.l. presents several morphological types of fruits, of which the schizocarp is the most common. The fruits of weed species of Euphorbia graminea Jacq., Euphorbia heterophylla L., Euphorbia hirta L. (= Chamaesyce hirta (L.) Millsp.) and Euphorbia prostrata Aiton (= Chamaesyce prostrata (Aiton) Small) are objects of this study. Inflorescences and fruits in development were collected on the campus of the State University of Maringa (UEM), Brazil, fixed in FAA 50 and glutaraldehyde, dehydrated and sectioned with a rotary microtome according to standard morphology and anatomy techniques. The species present several anatomical similarities, though there are some differences related to the outer epidermis of the ovaries, which is glabrous in E. graminea and hairy in the other species. The ripe fruits present a papilose exocarp and lack trichomes, except for E. hirta. The ovules are anatropous, bitegmic and crassinucellate; the seeds are exotegmic and the embryos are straight.