Pogostemon glaber Bentham (1830: 31)

YAO, GANG, DENG, YUN-FEI & GE, XUE-JUN, 2015, A Taxonomic Revision Of Pogostemon (Lamiaceae) From China, Phytotaxa 200 (1), pp. 448-450 : 448-450

7. Pogostemon glaber Bentham (1830: 31) . Lectotype (here designated): — NEPAL. “Nepalia”, no date, N. Wallich 1533 (K!, isolectotype K-W!).

Perennial herbs or bush, to 2 m tall. Stems erect, terete or 4-angular, branched, pubescent or subglabrous, glabrescent. Leaves opposite; petiole usually 3–5 cm long, sometimes up to 6.5 cm, subglabrous; blade ovate, 5–15 × 2.5–8 cm, adaxially sparsely pubescent or subglabrous, abaxially pubescent along veins otherwise glabrous, base broadly cuneate, cuneate, or round, margin double serrate or double crenate, apex acuminate, lateral veins 4–6 pairs on each side of the midvein. Spikes 3–15 cm × 6–10 mm, terminal and axillary, continuous or interrupted, with more than two lateral spikes; peduncle 0.5–4 cm long; verticillasters many-flowered, flowers sessile. Bracts and bracteoles ovate, 2.5–6 mm long, margin ciliate. Calyx tubular-inflated or subtubular, 3–4.5 mm long, 5-veined, glabrous, or pubescent outside, or sparsely pubescent only along veins; teeth 5, equal, triangular, ca. 1/3 as long as calyx tube, sparely pubescent or glabrous inside, margin ciliate. Corolla white, pink, purplish-white, or purple, 3.5–5.5 mm long, exserted, 2-lipped, upper lip 3-lobed, lobes apex obtuse, pubescent outside, lower lip entire, glabrous, apex acute. Stamens 4, exserted portion of filaments nearly as long as corolla; filaments bearded at middle, bearded portion exserted; anthers 1-locular, cell apex dehiscent; stigma bifid, equal, lobes 0.9–1.2 mm long. Nutlets 4, 0.5–0.6 mm long, globose, slightly flat, dark brown, shiny.

Infraspecific variation: — The hairs on leaves, bracts, bracteoles and calyx are variable within this species. Most populations in this species are pubescent or subglabrous on leaves, bracts and bracteoles as well as outer part of calyx. However, several populations of this species from southeastern and central Yunnan are villous on their leaves, bracts and bracteoles as well as the outer part of the calyx. Based on this observation, two subgroups are recognized as varieties, var. glaber and var. tsingpingensis .