Platystemma

Platystemma violoides Wall., type and only species

Wang et al., Fl. reipubl. pop. Sin. 69, t. 58 (1990); with permission.

Platystemma violoides Wall., type and only species; plants growing on a moist and shadowy rockwall in Nepal

Photo: © Kaj Halberg, with permission. Source: kajhalberg.dk/en/plants/plant-hunting-in-the-himalaya/among-annapurna-giants/

Platystemma violoides Wall., type and only species; close-up of flower

Photo: Nidhan Singh. Source: eFlora of India, efloraofindia.com/2013/08/30/platystemma-violoides/

Full name and orig. publication: Platystemma Wall., Pl. Asiat. Rar. 2: 42 (7 June 1831).

Etymology: From the Greek πλατυς, platys = broad, flat; and στεμμα, stemma = crown, corona, flower garland; the name means that the (short-tubed) corolla has a very flat limb.

Infrafamilial position: Didymocarpoideae-Trichosporeae-Leptoboeinae (Weber et al. 2013).

Description: Small slender herbs with a vertical rhizome. Aerial shoots with a single, sessile, orbicular-cordate, membranous, hairy leaf. Cyme emerging from the leaf axil, peduncle slender, bearing 1 to few flowers, bracteoles very small, sublinear. Sepals free nearly to base, forming a wide, campanulate calyx. Corolla violet, tube short, limb wide, deeply bilabiate, lobes wide-oblong, obtuse. Stamens 4, filaments short, curved; anthers apically coherent; thecae divaricate, apically confluent, dehiscing by a single short slit. Nectary annular. Ovary ovoid, style much longer than ovary, stigma inconspicuous. Capsule ovoid-oblong, splitting loculicidally (+ septicidally?), partially enclosed in persisting calyx.

Chromosome number: 2n = 40.

Type and only species: Platystemma violoides Wall.

Distribution: E & W Himalayas (Nepal, Bhutan, N India), SW China.

Ecology: On shady and damp rocks in valleys or dry cliffs, 2300-3200 m.

Notes: The habit of the tiny plant is most conspicuous, recalling to some degree the much larger Raphiocarpus sesquifolius.

Selected references: A. & D. DC. Prodr. 9: 279 (1845); Wang & al. in Wu & Raven (eds.), Fl. China 18:

Tax. details, cytology, and bibliography: Gesneriaceae Resource Centre (GRC). Royal Botanic Garden Edinburgh.

Page content and update responsibility/contact: Michael Möller.
Last update: