The genus Acacia Miller in South Africa. I. Stipules and spines

Abstract

A large number of seedlings and young twigs of South African  Acacia species was sectioned and the vascularization of the nodes and internodes studied. The nodes of all the species examined are trilacunate and the vascular tissue of the stipules originates from the lateral leaf traces. The Gummiferae species all have spinescent stipules, while stipules of the Vulgares species are membranous. Prickles containing no vascular tissue are found on the nodes and in some species also on the internodes of the Vulgares species. These prickles always occur on the ridges formed on the stem by leaf traces.