Botanical journal of the linnean society vol:137 issue:1 pages:1-29
A detailed morphological and anatomical study of the tropical African genus Virectaria is presented. The observations are used to characterize the genus, to propose a key to all eight species, and to unravel the relationships between the species using cladistics. A taxonomic survey of the genus is also given. Verdcourt's infraspecific taxa based on calyx morphology in V. major are adopted, but it was found that morphological distinction is correlated with ecological, habit and distributional differences. Hence, it is better to recognize Verdcourt's varieties spathulata and major as subspecies of V. major. The problematic systematic position of the genus is discussed in detail. New evidence is given for the exclusion of the genus from the Hedyotideae and Ophiorrhizeae (subfamily Rubioideae). The recently proposed position in the Sabiceeae (subfamily Ixoroideae) is not convincing either, since none of the genera included in the Sabiceeae matches Virectaria with respect to pollen, fruit, flower and growth habit. Exclusion from the Rubioideae and a position near the Sabiceeae is supported by lack of raphides, seed anatomy, placentation, stipule morphology and molecular evidence. Molecular data from a larger number of taxa are needed to confirm the position of the genus. (C) 2001 The Linnean Society of London.