Pogostemon amaranthoides Bentham (1848: 153)

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

1. Pogostemon amaranthoides Bentham (1848: 153) . Lectotype (here designated): — INDIA. Himachal Pradesh: near Simla, no date, J.D. Hooker s.n. (K!, isolectotypes MPU!, P!).

Pogostemon brevicorollus Y.Z. Sun in Sun & Hu (1966: 49), syn. nov. Type: — CHINA, Yunnan: Yangbi to Yongping , 1830 m, 12 November 1934, M. Chen 3206 (holotype PE, isotype NAS!).

Perennial herb or subshrub, to 1 m tall. Stems erect, quadrangular, branched, pubescent, then glabrescent. Leaves opposite; petiole ca. 1–4 cm long, pubescent; blade lanceolate to ovate, 6–13 × 1.5–6.5 cm, adaxially sparsely puberulent, abaxially minutely hispid on veins and densely glandular, base cuneate, margin double serrate except for entire at base, apex acuminate, lateral veins 4–6 pairs on each side of the midvein. Spikes 2–9 cm × 6–8 mm, terminal and axillary, interrupted, with more than two lateral spikes, peduncle 0.5–2.5 cm long; verticillasters globose, 6–14-flowered, flowers sessile. Bracts and bracteoles ovate-lanceolate or linear, 1–3.5 mm long, pubescent. Calyx ovoid-tubular or campanulate, 2–2.7 mm long, 5-veined, subglabrous or pubescent along veins outside; teeth 5, triangular, equal, 0.5–0.6 mm long, 0.5–0.6 mm wide at base, margin ciliate, glabrous inside, slightly inflexed in fruit. Corolla white or purplish, 2–2.6 mm long, subequal or slightly shorter than calyx in length, glabrous outside; tube 1.7–1.9 mm long; corolla limb 2-lipped, upper lip 3-lobed, lobes subequal, apex obtuse, lower lip entire, apex acute. Stamens 4, exserted; filaments 1.4–1.7 mm long, inserted at middle or slightly upper of middle in the tube, bearded at middle, bearded portion slightly exserted; anthers 1-locular, cell apex dehiscent. Style 2.4–3 mm long; stigma bifid, subequal, 0.5–0.7 mm long; disc. ca. 1/8 as long as calyx tube. Nutlets 4, ca. 0.8 mm long, obovoid or subglobose, abaxially slightly flat, adaxially ribbed, black or dark brown.

Distribution and habitat:— The species is widely distributed in Eastern Himalayan regions and known from Yunnan province in China ( Figure 2 ). This species was reported to be distributed in SW Sichuan province by Wu et al. (1977), Wu & Huang (1977) and Li & Hedge (1994), but we did not find any specimens from Sichuan. The species grows in mixed forests, margin of woods, or on open ravine, at the elevation of 1200–2800 m.

Phenology:— Flowering and fruiting from August to the following January.

Taxonomic notes:— Pogostemon amaranthoides can be easily distinguished from other species of Pogostemon subgen. Pogostemon by its calyx and corolla less than 3 mm long and the corolla shorter than or subequal to the calyx.

Pogostemon brevicorollus Y.Z. Sun in Sun & Hu (1966: 49) was described based on a specimen collected from Northwestern Yunnan and considered to be an endemic species in China ( Sun & Hu 1966, Wu et al. 1977, Wu & Huang 1977, Li & Hedge 1994). Bhatti and Ingrouille (1997) did not treat this species because no specimens were available for their studies. After examining the type material, P. brevicorollus is now considered identical with P. amaranthoides in all aspects.

In the protologue, Bentham (1848) cited two collections which are syntypes of Pogostemon amaranthoides . Both of them are consistent with the original description. Here we choose Hooker s.n in K as lectotype because we did not trace the other original syntypes collected by Griffith from Khasia and Assam, India .

Figures

FIGURE 2. Distribution maps of Pogostemon amaranthoides, P. chinensis, P. dielsianus and P. elsholtzioides.