Strobilanthes: Panicled Species from East Asia

Abstract

Summary. The species of Strobilanthes from East Asia with a paniculate inflorescence form a readily identifiable cluster of species, which reaches its greatest diversity on the Indonesian Island of Sumatra. The 16 species are enumerated, described and discussed. Three new species, Strobilanthes ramosissima (from Sumatra), S. tenuiflora (from Thailand) and S. euantha (from the China-Burma (Myanmar) border region) are described, a new name, S. bunnemeyeri is provided for Diflugossa glandulosa, and the new combinations S. ovatifolia and S. pubescens are made. A key is provided to facilitate identification. Several species are illustrated for the first time and maps show the distribution of all species discussed in this paper. The inflorescence in Strobilanthes is very variable with flowers arranged mostly in heads or spikes. These are often aggregated into panicles, but true open panicles with separate flowers are rare. Panicles are found in the cluster of species from Sri Lanka and South India placed by Nees (1832, 1847) and Bremekamp (1944) in the genus Leptacanthus, and also in East Asia in a group which was mostly included in Bremekamp's genus Diflugossa (1944: 237ff.). This latter group of about 17 species is the subject of this paper. The species cluster under discussion here is readily recognised by the paniculate inflorescence. All species have the commonest pollen type found in Strobilanthes, ellipsoid, ribbed and scalariform, but there are some anomalies in the pollen of two species, Strobilanthes panichanga and S. pedunculosa. Most species have a small, subequally 5-lobed calyx, the lobes with a distinct dark midrib lying between broad, pale margins and with prominent cystoliths. The tips of the calyx lobes are commonly obtuse and emarginate. Other features common to most species are the very pale, usually white, pale lilac or pale pink, straight corollas, and the caducous bracts and bracteoles, which are often absent by the time the flowers are fully open. None of these characters are restricted to the paniculate group and even the defining paniculate inflorescence intergrades with other inflorescence types where the arrangement is more obviously spicate, and particularly with the three following groups: * Those in which the flowers are in lax terminal spikes, particularly Strobilanthes collina Nees and S. tonkinensis Lindau.