Pogostemon brachystachyus Bentham (1848: 156)

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

12. Pogostemon brachystachyus Bentham (1848: 156) . Lectotype (here designated): — INDIA. Meghalaya State: “Khasia”, W. Griffith 3967 (K!, barcodes 513009; isolectotype K!). Figure 11 .

Pogostemon nigrescens Dunn (1913: 159) , syn. nov. Pogostemon fraternus Miq. var. nigrescens (Dunn) Kudô (1929: 52) . Lectoype (designated by Bhati & Ingrouille 1997: 107): — CHINA. Yunnan: Feng-che-lin Mts., no date, A. Henry 11174 (K!, isolectotypes A!, MO!, NY!, PE!).

Annual herbs, 20–70 cm tall. Stems erect, or procumbent and rooting at nodes sometimes basally, usually branched in large plants, densely pubescent with reflexed hairs. Leaves opposite; petiole 0.5–3.5 cm long, pubescent; blade ovate, 2–8.5 × 1.5–3.5 cm, blackish or brownish when dry, adaxially densely appressed pubescent, abaxially pubescent and densely along the veins, glandular on both surfaces, base obtuse, rounded, or cuneate, margin double crenate or serrate, apex acute to acuminate, lateral veins 3–5 pairs on each side of the midvein. Spike terminal, unbranched or sometimes with two lateral branches, 4–19 cm long, 1 cm wide, blackish or dark brown when dry, loose, continuous or subcontinuous, usually interrupted basally, densely pubescent; peduncle 1–3.5 cm long; verticillasters up to 20-flowered, rachis densely spreading gray pubescent, flowers with a short pedicel 1–2 mm long. Bracts and bracteoles linear or filiform, 1–2.5 mm long, margin ciliate. Calyx tubular-campanulate, 3–3.5 mm long in flower, ca. 4 mm long in fruit, 10-veined, green to purple in live plant, black or dark brown when dry, densely gray pubescent and glandular outside, densely white hirsute annulate inside; teeth 5, unequal, 0.9–1.1 mm long, upper three subulate, lower two narrowly triangular, margin ciliate; Corolla pink to purplish or purple, ca. 4 mm long, exserted from calyx, 2-lipped, upper lip 3-lobed, lobes apex obtuse, densely pubescent outside, lower lip entire, apex acuminate or acute, pubescent outside. Stamens 4, exserted; filaments pink, ca. 3 mm long, sparsely bearded at middle, inserted at the 1/2–2/3 height in corolla tube; anther 1-locular, cell apex dehiscent; style 4–4.5 mm long; stigma bifid, equal, lobes ca. 0.4 mm long. Disc ca. 0.5 mm long. Nutlets 4, 0.6–0.7 mm long, orbicular to obovoid, abaxially flat slightly, adaxially ribbed, black, shiny.

Distribution and habitat:— The species is distributed in Bhutan, Myanmar, India and China. In China, it occurs in Yunnan ( Figure 7 ). It grows in boscage, roadsides, slopes on hills, and forests at an elevation of 1100–2600 m.

Phenology:— Flowering from September to November and fruiting from October to December.

Uses:— In Yunnan, it is used as medicine for bellyache by the local people.

Taxnomic notes:— Pogostemon brachystachyus is similar to P. hispidocalyx C.Y. Wu & Y.C. Huang in Wu et al. (1977: 745) in habit, but differs from the latter by its leaf margin being double crenate or serrate (not acutely double serrate), lateral veins in 3–5 pairs (not 5–9 pairs), the calyx tubular-campanulate (not urceolate-campanulate) in fruit and densely gray pubescent (not sparsely hispid or subglabrous) outside, and sparsely bearded (not glabrous) stamens much exserted from the corolla (not included).

Pogostemon nigrescens was considered to be an independent species endemic to Yunnan, China, distinct from P. brachystachyus , in previous studies ( Wu & Huang 1977, Wu et al. 1977, Wu 1984, Li & Hedge 1994). Based on the original description and other previous descriptions ( Bentham 1848, Hooker 1885, Bhatti & Ingrouille 1997), P. nigrescens shares the same morphological characters with P. brachystachyus , e.g. stems procumbent at base, pubesecnt with reflexed hairs, ovate to ovate-lanceolate leaf blades, hirsute or finely tomentose, dense or loose spikes sometimes longer than 10 cm, the calyx about 4 mm long, hirsute or hispid and exhibiting an annulus of hairs on the tube inside, the teeth awl-shaped and fringed with bristles, a purple corolla about 4 mm long, the filaments sparsely bearded, and sub-orbicular nutlets. Examination of the type material and a large number of specimens reveals that P. nigrescens is conspecific with P. brachystachyus .

POGOSTEMON ( LAMIACEAE )

Phytotaxa 200 (1) © 2015 Magnolia Press • 21

In the original protologue, Dunn (1913) cited three collections (Henry 9082, 11174 and 12563) from Yunnan but did not designate a type. Bhatti & Ingrouille (1997: 107) indicated the specimen Henry 11174 in K as the holotype. In fact, they effectively chose the lectotype for the name Pogostemon nigrescens Dunn and the term “ holotype ” can be corrected as “ lectotype ” according to Article 9.9 of the ICN ( McNeill et al. 2012).

Figures

FIGURE 7. Distribution maps of Pogostemon parviflorus, P. septentrionalis, P. xanthiiphyllus and P. brachystachys.

FIGURE 11. Pogostemon auricularius. A. Habit; B. Bract; C. Flower; D. Calyx; E. Corolla and stamens; F. Ovary and style. Drawn by H.P. Yu based on C.L. Tso 21899 (IBSC) and provided by the Flora of Hong Kong project via Hong Kong Herbarium (HK)