Pogostemon pentagonus (C.B. Clarke ex Hook.f.) Kuntze (1891: 530)

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

Phytotaxa 200 (1) © 2015 Magnolia Press • 31 23. Pogostemon pentagonus (C.B. Clarke ex Hook.f.) Kuntze (1891: 530) . Dysophylla pentagona C.B. Clarke ex Hooker (1885: 641) . Eusteralis pentagona (C.B. Clarke ex Hook.f.) Panigrahi (1976: 477) . Anuragia pentagona (C.B. Clarke ex Hook.f.) Raizada (1976: 219) . Type: — INDIA. Bihar: Chota Nagpur, Singhboom, 28 October 1873, C.B. Clarke 20438 (holotype K!).

Annual herbs, 10–40 cm tall. Stems solid, terete, erect-ascending, base trailing, glabrous. Leaves in whorls of 4, sessile; blade linear to oblanceolate, 1–2.5 cm × 1–3.5 mm, glabrous, abaxially sparsely glandular, base attenuate, margin entire or slightly revolute, apex obtuse, lateral veins inconspicuouse. Spike terminal, simple, 1–4 cm × 8–9 mm, subcapitate; flowers subsessile. Bracts and bracteoles purplish, lanceolate or linear, subequal as long as the corolla, pubescent, margin gray villous. Calyx campanulate, ca. 1 × 0.8 mm, 5-veined, 5-sulcate, pilose and glandular outside, glabrous inside; teeth 5, triangular, margin ciliate. Corolla reddish, ca. 2 times as long as the calyx, subequally 4-lobed. Stamens 4, much exserted; filaments inserted at a same height in the tube, bearded; anthers 1-locular, cell apex dehiscent; style ca. 3.5 mm long; stigma bifid, lobes unequal. Nutlets 4, ca. 0.7 × 0.4 mm, oblong, 4-angled, light brown.

Distribution and habitat:— The species is distributed in China, India, Thailand, and Vietnam. In China, it occurs in southern Yunnan ( Figure 16 ). It grows occasionally in marshy grounds, at ponds, or near streams, at 800–1550 m elevation.

Phenology:— Flowering and fruiting from October to the following May.

Taxonomic notes:— Pogostemon pentagonus is similar to P. faurei in having small leaves, but differs from the latter by its calyx ca. 1.2 mm long (not longer than 2 mm), corolla ca. 2.5 mm long (not ca. 3.3 mm) and distributed in south Yunnan (not Heilongjiang).

Figures

FIGURE 16. Distribution maps of Pogostemon linearis, P. pentagonus, P. sampsonii and P. stellatus.