Vegetative anatomy and relationships of Setchellanthus caeruleus (Setchellanthaceae)

Abstract

SummaryCarlquist, S. & Miller, R. B.: Vegetative anatomy and relationships of Setchellanthus caeruleus (Setchellanthaceae). – Taxon 48: 289‐302. 1999. – ISSN 0040‐0262.On account of its distinctive features, Setchellanthus cannot be included within any of the families of glucosinolate‐producing plants. Features unknown in any of these families include abundant vasicentric tracheids, abaxial axial parenchyma, and only short uniseriate rays (composed of upright cells) in wood; and the presence of wide‐helix tracheary elements in leaves. Wood offers the greatest number of phyletically significant features, and wood of Capparaceae offers many similarities, although the wood of Helianthemum (Cistaceae) is even more like that of Setchellanthus. Despite the fact that no myrosin cells were observed in Setchellanthus, it appears closest, on the basis of present information, to the glucosinolate‐producing families.