A survey of anther glands in the mimosoid legume tribes Parkieae and Mimoseae

In a broad survey of anther glands in the mimosoid legume tribes Mimoseae and Parkieae, representatives from 30 genera with anther glands were studied using scanning electron microscopy. Four kinds of anther glands could be distinguished. The Piptadenia-type gland, found in all but four of the genera surveyed, is usually spherical to ellipsoid in shape and often borne on a stipe. The cells making up the gland vary in size among species and are often sculptured. Six different kinds of sculpturing can be recognized: smooth, reticulate, striate, rugulate, scabrate, and papillate. The Gagnebina-type gland is the least specialized, consisting of a simple extension of the connective with irregularly projecting cells. The Prosopis africana-type gland is borne ventrally between the thecae, the connective extending hump-like over the apex of the anther. The Pentaclethra-type gland, found only in the genus Pentaclethra, is distinguished by a median dorsal furrow and a ventral conical structure similar to a food body or osmophore. Anatomical sections revealed two different subtypes within the Piptadenia-type gland. Some glands are composed of a homogeneous matrix of isodiametric cells, whereas others have two layers: a peripheral layer of large radially elongated cells, and a central sphere of smaller isodiametric cells and large air spaces. Some characters of anther glands have clear taxonomic significance, and more detailed surveys within genera will undoubtedly provide additional taxonomic markers.