Pogostemon glaber var. glaber

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

7a. Pogostemon glaber var. glaber . Figure 5 .

Caryopteris esquirolii Léveillé (1911: 449) . Pogostemon esquirolii (H. Lév.) C.Y. Wu & Y.C. Huang in Wu et al. (1977: 743). Type : — CHINA. Guizhou: “Kouy-Tcheou, Tchou-Ly”, 900 m, 1 January 1910, J. Esquirol 2053 (holotype E!).

The leaves, bracts and bracteoles, and outer part of calyx pubescent or subglabrous.

Distribution and habitat:— The variety is widespread from northwestern India and Nepal to Thailand, Laos, Vietnam, and China. In China, it is known from Yunnan, Guangxi, Hainan and Guizhou provinces ( Figure 4 ). It is common in waste flats, ravines, thickets or forests, grass slopes, beside the stream or on road side at an elevation of 400–2700 m.

Phenology:— Flowering and fruiting from November to the following March.

Taxonomic notes:— Caryopteris esquirolii was first described in 1911 based on a specimen collected from

14 • Phytotaxa 200 (1) © 2015 Magnolia Press

DENG & GE

Guizhou, China and transferred to Pogostemon by Wu et al. (1977). However, many Chinese taxonomists (Chun 1977, Wu et al. 1977, Wu & Huang 1977, Li & Hedge 1994) were not aware that it had been reduced to the synonymy of P. glaber by Rehder (1935). Wu et al. (1977) and Wu & Huang (1977) recognized P. esquirolii as a separate species and differentiated it from P. glaber by characters of its continuous or interrupted spikes 3–9 cm in length, rarely to 12 cm, a subtubular calyx, ca. 4 mm long, and the corolla 6–7 mm in length. It can be observed that P. glaber has continuous or interrupted spikes, 2–12 cm in length, rarely up to 20 cm, an ovoid-tubular calyx, ca. 3 mm long, and the corolla ca. 5 mm long. Flora Hainanica ( Guangdong Institute of Botany 1977) noted that “spikes wide and short, continuous, calyx 4–5 mm long presented in P. esquirolii , while spikes slim, continuous or interrupted, calyx 2.5–3 mm long in P. glaber .” However, after observing a larger number of specimens, the boundaries between them are not clear and the morphological characters used to discriminate the two species were found to be variable. The calyx length is variable from 3 mm to 4.5 mm, and the length of corolla is variale from 3.5 mm to 5.5 mm. The calyx up to 5 mm in length and corolla up to 6–7 mm in length as mentioned by Wu et al. (1977) and Wu & Huang (1977) are not observed in our present investigations. In addition, types of P. glaber and P. esquirolii are very similar in characters of the spike and the calyx. The spikes are continuous and about 2.5–8 cm in length, calyx ca. 4 mm long can be observed in the type of P. glaber , while spikes are continuous and about 2.5–5.5 cm in length, calyx ca. 3.5–4 mm long, corolla ca. 5 mm long present in the type of P. esquirolii . Therefore, we agree with the treatment by Rehder (1935) who proposed to reduce P. esquirolii to P. glaber .

Figures

FIGURE 4. Distribution maps of Pogostemon formosanus, P. glaber var. glaber, P. glaber var. tsingpingensis and P. latifolius.

FIGURE 5. Pogostemon glaber var. glaber. A. Habit; B. Bract; C. Flower; D. Calyx; E. Ovary and style. Drawn by H.P. Yu based on Hainan Expedition 779 (IBSC).