Fruit structure and some details of fruit morphogenesis in subfamily Tripterygioideae Loes. (Celastraceae R. Br.)

Abstract

Fruit structure and morphogenesis in subfamily Tripterygioideae Loes. (Celastraceae R. Br.) are presented. Fruits are either with 2, 3 or 5 lateral wings, nested along the fruit, or with one apical wing (on the fruit's sides and its apex). The wings are wide or narrow, membranous; the body of the fruit is shorter than its wings. The wings usually possess a net of vascular bundle derivates. The topography of vascular bundles defines the way of pericarp expansion. For all examined fruits style on the apex always remains. Peculiarities of pericarp structure and development suggest morphogenetical type of the fruit in Tripterygioideae-pseudomonomerous unilocular one-seeded winged pyrenarium with a pyrene, which can be formed by 3 to 5 layers of tangential elongated macrosclereids (in many examined taxa). Fruit type of Ptelidium is uni-or bilocular and one(two)-seeded nut, because its pericarp is lignified entirely. Fruit of Rzedowskia has only one layer of radially elongated sclereids in endocarp. Seeds of all examined species are small, without aril. Two genera appeared to be more isolated-Ptelidium and Rzedowskia. All examined taxa have demonstrated one special evolutional trend in common-the reduction of the number of seeds per fruit and the development of wings as an adaptation to the dispersal by wind. According to the latest molecular data, such fruit types have been formed in Celastraceae at least six times in the course of evolution.