Pogostemon stellatus (Lour.) Kuntze (1891: 529)

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

25. Pogostemon stellatus (Lour.) Kuntze (1891: 529) . Mentha stellata Loureiro (1790: 361) . Dysophylla stellata (Lour.) Bentham (1830: 30) . Eusteralis stellata (Lour.) Panigrahi (1976: 474) . Anuragia stellata (Lour.) Raizada (1976: 218) . Mentha quadrifolia B. Heyne ex Roth (1821: 256) , nom. illeg. Type: — VIETNAM. “loco humido inculta in Cochinchina”, no date, J. de Loureiro s.n. (holotype BM!). Figure 18 .

Dysophylla verticillata Bentham (1830: 30) . Pogostemon verticillatus (Benth.) Miquel (1856: 965) . Anuragia verticillata (Benth.) Raizada (1976: 218) . Lectotype (designated by Panigrahi 1976: 474): — BANGLADESH. Sylhet, no date, N. Wallich 1544 (K-W!).

Mentha verticillata Roxburgh (1832: 5) , nom. illeg, non Mentha verticillata Don (1825: 114) . Pogostemon verticillatus Bhatti & Ingrouille (1997: 115) , nom. illeg., non Pogostemon verticillatus (Benth.) Miquel (1856: 965) . Lectotype (here designated):— INDIA. BANGLADESH. “Panee-kula”, no date, W. Roxburgh 159 (BM!, isolectotype K!).

Dysophylla benthamiana Hance (1866: 234) . Pogostemon benthamianus (Hance) Kuntze (1891: 530) . Type: — CHINA. Guangdong: Cantonem (now Guangzhou), August 1864, G.T. Sampson in Herb. Hance 11448 (holotype BM!, isotypes K!, P!).

Dysophylla esquirolii Léveillé (1912: 476) . Type: — CHINA. Guizhou: Teng-Chang , riziéres, September 1904, J. Esquirol 155 (holotype E!).

Dysophylla . benthamiana Hance var. hainanensis C.Y. Wu & S. J. Hsuan in Wu et al. (1965: 238). Dysophylla stellata (Lour.) Benth. var. hainanensis (C.Y. Wu & S.J. Hsuan) C.Y. Wu & H.W. Li in Li (1975: 77). Type: — CHINA. Hainan: Chungtzao, Nor-da, 21 November 1921, F.A. McClure 1688 (holotype SYS!).

Annual herbs, 15–80 cm tall. Stems solid, strong or slim, terete with shallow grooves, erect or erect-ascending but base procumbent, trailing at base, lower internodes short (occasionally with long internodes basally), many branches in tall plant, glabrous, nodes sometimes gray villous. Leaves in whorls of 4–8, sessial; blade linear, 2–7 cm × 1.5–4(–7.5) mm, glabrous, glandular abaxially, base attenuate, margin remote serrulate or entire, revolute or flat, apex acute, lateral veins inconspicuouse. Spike terminal, simple, 0.5–9 cm × 4–8 mm, continuous and compact; flowers subsessile. Bracts lanceolateor ovate, ca. 1.5 mm long, bracteoles linear or filiform, slightly shorter or subequal as long as the calyx. Calyx campanulate, 1–1.1 mm long in flower, enlarge to 1.6 mm long in fruit, 5-veined, densely gray tomentose outside; teeth 5, triangular, equal, ciliate. Corolla purple-red, 1.5–1.8 mm, exserted, subequally 4-lobed. Stamens 4, exserted; filaments ca. 1.5 mm long, bearded portion slightly exserted from corolla; anthers 1-locular, cell apex dehiscent; style 1.8–2 mm long; stigma bifid, lobes subequal, 0.4–0.5 mm long; disc ca. 0.2 mm long. Nutlets 4, 0.5–0.6 mm long, ellipsoid to subglobose, brown or dark brown.

Distribution and habitat:— The species is widely distributed in Bangladesh, Bhutan, Cambodia, China, India, Indonesia, Japan, Laos, Malaysia, Thailand, Vietnam, and extends to Australia. In China, it occurs in Anhui, Guangdong, Guangxi, Hainan, Hunan, Jiangxi, Taiwan, Yunnan, and Zhejiang ( Figure 16 ). It is very common in rice paddies, wet areas along streams or pools, at an elevation of 300–1500 m.

Phenology:— Flowering and fruiting nearly the whole year.

34 • Phytotaxa 200 (1) © 2015 Magnolia Press

DENG & GE

Taxonomic notes:— Pogostemon stellatus is variable in the following characters: stem slim with long internodes or strong with short internodes basally, leaves in whorls of 4–8, margin dentate or sometimes entire and revolute, nutlets ellipsoid to ellipsoid-oblong or oblong in shape.

Pogostemon stellatus was treated as conspecific with P. verticillatus by many authors ( Miquel 1856, Kuntze 1891, Doan 1936, Panigrahi 1976, Wu et al. 1977, Wu & Huang 1977, Li & Hedge 1994), but Hooker (1885) and Bhatti & Ingrouille (1997) treated them as independent species. Hooker indicated that P. stellatus can be distinguished from P. verticillatus by the characters of the stem decumbent or creeping at base (not erect), the leaf

POGOSTEMON ( LAMIACEAE )

Phytotaxa 200 (1) © 2015 Magnolia Press • 35 margin revolute (not revolute or obscurly toothed), and calyx teeth erect (not stellately spreading). Bhatti & Ingrouille (1997) differentiated P. stellatus from P. verticillatus by the stems with short internodes (not long and weak), leaves in whorls of 4–8 (not up to 6), leaf margin entire and revolute (not dentate), spikes ca. 5.5 cm long (not 6–16 cm long), nutlets oblong (not ellipsoid to ellipsoi-oblong). However, we find that the morphological characters used to separate them by Hooker (1885) and Bhatti & Ingrouille (1997) are continuous and variable and here treat them as same species. In addition, the long spikes (c. 6–16 cm long) as mentioned by Bhatti & Ingrouille (1997) were not observed in the present study.

Bhatti & Ingrouille (1997: 115) published the new combination Pogostemon verticillatus (Roxb.) Bhatti & Ingrouille based on Mentha verticillata Roxburgh (1832: 5) . However, according to the Articles 52.1 and 58.1 of ICN ( McNeill et al. 2012), they published a new name rather than a new combination because the name Mentha verticillata Roxb. is a later illegitimate homonym of Mentha verticillata Don (1825: 114) .

Figures

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

FIGURE 18. Pogostemon stellatus. A. Habit; B. Leaf; C. Flower; D. Calyx; E. Corolla and stamens; F. Ovary and style. Drawn by H.P. Yu based on X.R. Liang 61180 (IBSC) and provided by Flora Hong Kong project via Hong Kong Herbarium (HK).