Stem and root anatomical correlations with life form diversity, ecology, and systematics in Moringa (Moringaceae)

Four life forms (habits) are identified in the 13 species of Moringa (bottl e trees, sarcorhizal trees, slender trees, and tuberous shrubs) which are e xamined for wood anatomical correlations with habit, ecology, and systemati cs. Wood anatomy is similar within habit classes except for the sarcorhizal trees. The four bottle tree species and M. arborea (one of the sarcorhizal trees) are characterized by bands of confluent paratracheal parenchyma alt ernating with bands of libriform fibres, some of which may be parenchyma-li ke. The other sarcorhizal tree, M. ruspoliana, is characterized by alternat ing bands of parenchyma-like and long, slender libriform fibres. Root secon dary xylem of all these species is characterized by bands of parenchyma and fibres. Slender trees do not show bands of fibres of different shapes and have fibrous roots with less parenchyma than the other species. Tuberous sh rubs have stems mostly composed of long, slender fibres and large undergrou nd tubers mostly composed of parenchyma. Quantitative trends between ecolog ically different localities include wider vessel elements and higher conduc tive area in moister localities. Wood anatomy provides characters that are of potential phylogenetic utility at a variety of levels of relationship, B ased on wood anatomy and geography, the most likely sister taxon to Moringa is Cylicomorpha (Caricaceae). (C) 2001 The Linnean Society of London.