Abstract
The development of the ovule and the embryo sac of five of the 17 species of Lycium and of one hybrid, recorded for southern Africa, was investigated. All specimens of four of the species and the hybrid (between a hermaphroditic and a functionally dioecious species) were found to be functionally dioecious: they express only one sex, although both male and female organs are present in the same tlower. One species was hermaphroditic. The embryo sacs of all species, and of the hybrid, were of the normal eight-nucleate Polygonum type. The structure of the ovary and the development of the embryo sac are similar to those of L europaeum L. The absence of unreduced embryo sacs indicates that apomixis does not occur at any ploidy level in the species studied.
Highlights
The genus Lycium (Solanaceae) consists of small to large shrubs with a wide distribution in arid to subarid. temperate to subtropical regions of the world (Joubert 1981; Bemardello 1982)
A study of a large number of specimens of Lycium in southern African herbaria, Kew (K), British Museum (BM), Paris (P) and a few other herbaria revealed that all specimens of L arenicolum, L. horridum, L. tetrandrum
The nuclei of the synergids, egg cell, central cell and antipodal cells were the same size in the her maphroditic L afrum and the functionally male plants of L. horridum
Summary
The genus Lycium (Solanaceae) consists of small to large shrubs with a wide distribution in arid to subarid. temperate to subtropical regions of the world (Joubert 1981; Bemardello 1982). The genus Lycium (Solanaceae) consists of small to large shrubs with a wide distribution in arid to subarid. The only exceptions, which are more treelike, are L afrum L. and L horridum Thunb. Seventeen Lycium species are known in southern Africa, whereas 5 0-6 0 species are found in the western hem isphere (Joubert 1981). Polyploidy occurs in the genus Lycium (Minne 1992; Spies et al 1993). As polyploidy and apomixis are often associated (Stebbins 1971). The aim of this research was to determine whether apomixis occurs in the polyploid specimens. The mode of development of the ovule and the type of embryo sac present in L afrum. L. arenicolum, L horridum and L. tetrandrum was studied
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