Contribution of vegetative anatomy to the systematics of the Zygophyllaceae R.Br

SHEAHAN, M. C. & CUTLER, D. F., 1993. Contribution of vegetative anatomy to the systematics of the Zygophyllaceae R.Br. The Zygophyllaceae sensu lato are a heterogeneous family of trees, shrubs and herbs growing in arid and semi-arid areas of the world. There has been disagreement about the systematic status of some groups within the family, and the position of Balanites has also been disputed. The vegetative anatomy of the family was examined to see if it could throw light on current systems of classification. The anatomy of 37 species in 19 genera is described, and the results of tests of C₄ activity in 27 species are given. There is anatomical evidence to support the exclusion of Balanites into a separate family, and some groups (Engler's Peganoideae and Nitrarioideae) have characteristics which set them apart from the rest of the family. This is in accordance with other analyses of the family based on morphological, palynological and biochemical studies. There is also evidence that the tribuloid genera Tribulus, Kallstroemia and Kelleronia should be separated from the zygophylloid genera, at least at subfamily level; however, Neoluederitzia and Sisyndite should remain in the Zygophylloideae. Brief reference is made to relationships with other families in the Geraniales.