Hair micromorphology and its phylogenetic application in thorny species of Astragalus (Fabaceae)

A comprehensive survey and descriptions of hair characters in thorny species of Astragalus have been conducted using light and scanning electron microscopy. Attention was paid to hair colour, length, shape and papillae on the hair surface. On the basis of already defined phylogenetic relationships among the species in this group, apomorphic and plesiomorphic states are suggested for hair characters. The presence of black hairs in the region of inflorescence, papillae on the hair surface and flattened ribbon-like hairs are the most important plesiomorphies. Moreover, there is a tendency to have long hairs in several advanced groups. Astragalus sect. Acanthophace, A. sect. Adiaspastus, A. sect. Aegacantha, A. sect. Anthylloidei and A. sect. Stipitella present the most primitive hair types in the thorny group. These sections have also been previously established as primitive with respect to several other morphological characters such as pod structure and the shape of the standard. (C) 2003 The Linnean Society of London, Botanical Journal of the Linnean Society.