Carex tsoi Merr. & Chun (1935: 207)

Jin, Xiao-Feng, Cen, Jia-Meng, Hahn, Marlene, Lu, Yi-Fei & He, Jin-Jing, 2015, Notes on Carex (Cyperaceae) from China (II): a taxonomic revision of sect. Radicales (Kük.) Nelmes, Phytotaxa 217 (2), pp. 117-132 : 131

(12) Carex tsoi Merr. & Chun (1935: 207) . Type:— CHINA. Hainan: Dung ka, Wen Fa Shi , 24 Aug 1932, N. K. Chun & C. L. Tso 43680 (holotype, K!; isotype, IBK!, PE!) ( Figure 5 : H–L) .

Perennial herbs. Rhizomes long, ligneous. Culms densely caespitose, 3–15 cm tall, filiform, soft, compressed trigonous, smooth. Leaves longer than culms, or equal in length, flat, 1–5.5 mm wide, soft, glabrous, with dark brown persistent sheaths at base. Involucral bracts scale-like; blades setiform. Spikes 1–5, ovoid or oblong-ovoid, 2–5 mm long, ca. 3.5 mm wide, androgynous, remote, few flowered; staminate part of spike shorter than or nearly equaling to pistillate part. Staminate scales white or pale green, ovate, ca. 1.5 mm long, rounded or obtuse at apex, green 1-veined costa. Pistillate scales white or greenish white, ovate, obtuse at apex, green 1-veined costa. Perigynia longer than pistillate scales, ovoid, compressed trigonous, pale green, 2–2.5 mm long, sparsely pubescent, ciliate at margins, distinctly 2- veined laterally and thinly veined, cuneate at base, attenuate into an inconspicuous short beak at apex; orifice obliquely truncate. Achenes obovoid, trigonous, dark brown at maturity, 1–1.5 mm long, cuneate at base, with a slightly curved beak at apex; style thickened, slightly compressed, densely brown granular-punctate; stigmas 3.

Additional specimens examined:— CHINA. Hainan: Baoting, Taipinggang, K. C. How 72478 (PE). Dung ka, N. K. Chun & C. L. Tso 43962 (E, PE). Gan’en (Kan-en), Mount. Chim-Fong, S. K. Lau 5278 (KYO). Ledong, S. K. Lau 27397 (KYO, PE). Lingshui, Mount. Jian, H. Fung 20080 (K, KYO, PE, TI); Mount. Hongmao, W. T. Tsang & H. Fung 579 (K, PE). Wuzhishan, Mount. Wuzhi, X. F. Jin 2994 (HTC), 2995 (HTC). Yaxian, Shanmantou, C. Wang 33414 (PE).

Note:— This species is similar to Carex planiscapa Chun & How. Both species have 2–3 mm long perigynia which are inconspicuously beaked at the apex, and densely granular-punctate styles. C. tsoi differs from C. planiscapa by having filiform culms, and ovoid spikes <5 mm long.

Figures

FIGURE 5. A–E: Carex tsaiana F. T. Wang & Tang ex P. C. Li. (A) habit; (B) staminate scales; (C) pistillate scale; (D) perigynium; (E) achene. F, G: Carex daxinensis Y.Y. Zhou & X. F. Jin. (F) perigynium; (G) achene. H–L: Carex tsoi Merr. & Chun. (H) habit; (I) staminate scales; (J) pistillate scale; (K) perigynium; (L) achene. M–R: Carex planiscapa Chun & How. (M) spike; (N) transverse section of culm; (O) staminate scales; (P) pistillate scale; (Q) perigynium; (R) achene. (A–E drawn from H. T. Tsai 60957 in KUN, F, G from X. F. Jin & Y. Y. Zhou 3026 in HTC, H–L from X. F. Jin 2995 in HTC; M–R from Hainan Exped. 621 in IBK; drawn by Xiao-Feng Jin).