Pogostemon latifolius (C.Y. Wu & Y.C. Huang) Gang Yao, 2015

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

8. Pogostemon latifolius (C.Y. Wu & Y.C. Huang) Gang Yao , comb. et stat. nov. Basionym: Pogostemon griffithii Prain var. latifolius C.Y. Wu &Y.C. Huang in Wu et al. (1977: 744). Type : — CHINA. Yunnan: Ximeng , 700 m, 11 March 1958, Y.C. Du 580208 (holotype KUN!).

Perennial herbs, to 2 m tall. Stems erect, 4-angular, densely appressed pubescent. Leaves opposite; petiole 0.5–1.5 cm long, pubescent; blade ovate to broadly ovate, 5.5–8.5 × 3–5.8 cm, herbaceous, adaxially appressed pubescent, abaxially densely pubescent, base broadly cuneate, margin irregularly double serrate, apex acute, lateral veins ca. 3 pairs on each side of midvein, conspicuously prominent abaxially. Spikes cylindric, (1.5–)5.5–10 × 1–1.2 cm, terminal and axillary, interrupted basally, with more than two lateral branches; peduncle 0.5–3.5 cm long; verticillasters many-flowered, densely appressed pubescent, flowers sessile. Bracts and bracteoles ovate-lanceolate to lanceolate, 1.5–3 mm, densely pubescent, margin ciliate. Calyx narrowly campanulate, 4–5 mm long, 5-veind, densely pubescent outside; teeth 5, narrowly triangular, equal, 1–1.5 mm long, 0.7–0.8 mm wide at base, 1/3–1/2 as long as calyx tube, margin ciliate. Corolla bluish, ca. 6 mm long, exserted, 2-lipped, upper lip 3-lobed, sparsely pubescent outside, lower lip entire. Stamens 4, much exserted, bearded at middle, bearded portion exserted; anthers 1-locular, cell apex dehiscent. Stigma bifid, subequal, lobes 2–2.5 mm long. Nutlet unknown.

Distribution and habitat:— The species is endemic to China and occurs in southwestern Yunnan ( Figure 4 ). It is known only from the type locality. It grows in dense valley forests, at the elevation of ca. 700 m.

Phenology:— Flowering in March.

Taxonomic notes:— The species was described as Pogostemon griffithii var. latifolius C.Y. Wu & Y.C. Huang in Wu et al. (1977: 744). Li & Hedge (1994) noted that P. griffithii var. latifolius might be only a form of P. griffithii and that more material is needed for resolution. Bhatti & Ingrouille (1997) reduced it to be a synonym

POGOSTEMON ( LAMIACEAE )

Phytotaxa 200 (1) © 2015 Magnolia Press • 15 of P. griffithii . However, as indicated by Wu et al. (1977) and Wu & Huang (1977), this taxon is different from the latter by its ovate or broadly ovate leaves 5.5–8.5 × 3.5–5.8 cm (not lanceolate, 10 × 2.5–3 cm), the spikes (1.5–)5–10 × 1.2 cm (not 2–6 cm × 8 mm), the calyx 4–5 mm long (not ca. 4 mm long). Furthermore, after checking type materials of both, more morphological differences between them were observed. P. griffithii var. latifolius is characterized by the 4-angular stems, an irregularly double serrate leaf margin, lateral veins in 3 pairs, calyx teeth 1/3–1/2 as long as calyx tube, corolla ca. 6 mm long, stigma lobes 2–2.5 mm long. P. griffithii var. griffithii has stems terete, leaf margin dentate or obscurely dentate, lateral veins 6–8 pairs, calyx teeth subequal to 1/2 as long as the calyx tube, corolla ca. 5 mm long, stigma lobes ca. 1.2 mm long. Therefore, we raise P. griffithii var. latifolius to specific rank.

Figures

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