Carex procumbens H. B. Yang, X. X. Li & G. D. Liu, 2015

Yang, Hu-Biao, Li, Xiao-Xia, Bai, Chang-Jun, Wang, Wen-Qiang, Wang, Qing-Long, Yu, Dao- Geng, Dong, Rong-Shu & Liu, Guo-Dao, 2015, Carex procumbens (Carex sect. Rhomboidales, Cyperaceae), a new species from Hainan, China, Phytotaxa 201 (3), pp. 207-213 : 208-211

Carex procumbens H. B. Yang, X. X. Li & G. D. Liu sp. nov. ( Figures 1–3 ).

The new species is similar to C. longipetiolata , but apparently differs from the latter by having culms ca. 1 mm thick, prostrate on the ground (ca. 2–4 mm thick, erect); blades ca. 5 mm wide (1–1.5 cm wide, with ca. 10 cm petiole); inflorescence with 2–3 spikes, with short peduncle (with 3–4 spikes, all sessile); terminal spike 8–12 mm long (15–40 mm long); lateral spikes 5–15 mm long (10–20 mm long); staminate glumes ovate, ca. 3 mm, apex rounded (oblong-lanceolate, ca. 6.5 mm, apex acute); pistillate glumes ovate-lanceolate, ca. 6 mm (ovate, 5–6 mm); perigynia fusiform, green, 7–10 × 3 mm, glabrous (ovate-lanceolate, pale green, 7–8 × 2 mm, sparsely hispid); nutlet ca. 7 mm long, brown to dark brown, ovate-rhomboid, base with a shortly stipitate, apex with a curved beak (brown to dark brown but beak and angles yellowish white, elliptic-rhomboid, ca. 5.5 mm, base no stipitate, apex with a long erect beak).

Type: — CHINA. Hainan: Lingshui County, Diaoluo Shan Nature Reserve , moist place near the stream under forest, alt. 900–1 200 m, 28 February 2014, Yang Hubiao 20140228001 (holotype, IBSC!; one isotype, IBSC!; four isotypes, TCGRI!) .

Perennial; rhizome short, covered with dark brown fibrous remains of old leaf sheath. Culms central, 10–30 × ca. 0.1 cm, trigonous, usually prostrate on the ground. Leaves basal, green, blades linear, 15–40 × ca. 0.5 cm, flat, glabrous on both surfaces, apex acuminate, margins antrorsely scabrous, base gradually narrowed. Bracts leafy, the lowermost one surpassing inflorescence, sheathing, sheath ca. 5 mm long, green. Inflorescence paniculiform, contracted, headlike, comprising 2–3 crowded spikes; terminal spike staminate, 8–12 × 1 mm, linear-cylindrical, with peduncle ca. 5 mm; lateral spikes pistillate, 5–15 × ca. 5 mm, cylindrical, with peduncle 5–8 mm long, loosely flowered, with 1–10 flowers. Staminate glumes ca. 3 mm, ovate, membranous, glabrous, middle vein green, apex rounded; pistillate glumes ca. 6 mm, ovate-lanceolate, membranous, glabrous, middle vein green, middle vein excurrent into a short awn for ca. 2 mm. Perigynia longer than the glumes, green, 7–10 × 3 mm, fusiform, obscurely trigonous, membranous, glabrous, many veined, apex attenuate into a beak for ca. 2 mm. Nutlet ca. 7 mm long, brown to dark brown, tightly enveloped by the perigynium, ovate-rhomboid, trigonous with angles constricted at the middle, base shortly stipitate, apex abruptly contracted into a curved short beak of 1 mm; persistent style, base thickened. Fl. and fr. January–April.

Distribution and Habitat:— Carex procumbens is known only from Diaoluo Shan Nature Reserve, Hainan, China. It grows in a moist place near the stream under the tropical mountain rain forest. Associates include the trees Altingia obovata Merrill & Chun , Cryptocarya maclurei Merrill , Dacrydium pectinatum de Laubenfels , Manglietia fordiana var. hainanensis (Dandy) N. H. Xia ; the shrubs Symplocos ovatilobata Nooteboom , Ardisia baotingensis C. M. Hu ; and the herbs Hypolytrum nemorum (Vahl) Sprengel , Carex perakensis C. B. Clarke , Dianella ensifolia (Linnaeus) Redouté , Scleria terrestris (Linnaeus) Fasset.

Phenology:—Flowering begins in January with seeds reaching maturity in February to April.

Etymology:—The epithet “ procumbens ” refers to the culms, which are soft and usually prostrate on the ground.

Conservation status:—The new species is known from an area of less than 10 km 2. Survey found five small population intermittent distribute along the stream from the altitudes 900 to 1200 m. One randomly selected population, for statistics, which consists of approximately 140 caespitose individuals covering an area of 50 m 2. According to D2 of the IUCN (2001) category and criteria, C. procumbens is a vulnerable species (VU). Fortunately, this locality is in a remote place in the Diaoluoshan Natural Reserve.

Relationships:—The new species is placed in Carex sect. Rhomboidales because of its trigonous nutlets, constricted in the middle part and mitrate at the apex. In Hainan Island, two species of C. sect. Rhomboidales were recorded previously ( C. harlandii Boott and C. saxicola Tang et F. T. Wang ). In addition, C. longipetiolata Q.L. Wang, H.B. Yang & Y.F. Deng has recently been reported on the island ( Wang et al. 2012). However, C. procumbens can be easily distinguished from C. harlandii and C. saxicola by its lateral spikes being entirely female, whereas the latter two are androgynous. Carex procumbens is closely related to C. longipetiolata in the characters of culms central, nutlets trigonous with angles constricted at middle and leaves base gradually narrowed, but differs from the latter in culms soft and usually prostrate on the ground, leaf blades ca. 5 mm wide; with 2–3 spikes, terminal spike 8–12 mm long, lateral spikes 5–15 mm long and loosely flowered; staminate glumes apex rounded, pistillate glumes ovate-lanceolate ca. 6 mm and middle vein excurrent into a short awn for ca. 2 mm; perigynia fusiform and glabrous; nutlet ca. 7 mm long, apex with a short curved beak and base with shortly stipitate. According to the above characteristics C. procumbens and C. longipetiolata are clearly different ( Fig. 1 ; Fig. 2 , K–L and M–N). Carex procumbens can be distinguished from its related species by the following key.

Paratypes:— CHINA. Hainan: Lingshui County, Diaoluo Shan Nature Reserve, moist place near the stream under forest, alt. 900–1 200 m, 17 March 2014, Yang Hubiao 20140317002 (five paratypes, TCGRI!).

Key for the C. Sect. Rhomboidales species occurring in Hainan.

1a. Lateral spikes androgynous. 2a. Leaves 10–22 mm wide; perigynia 9–10 mm long and glabrous; nutlets, ca. 7 mm long, apex abruptly contracted into a slender and erect beak, base with curved stipitate ...................................................................................................................1. C. harlandii 2b. Leaves 8–10 mm wide; perigynia 7–8 mm long and sparsely pubescent; nutlets ca. 4 mm, apex abruptly contracted into a narrowly cylindric curved beak, base thickened.................................................................................................................2. C. saxicola 1b. Lateral spikes pistillate. 3a. Leaves 10–15 mm wide; culms erect; perigynia ovate-lanceolate, 7–8 mm long, sparsely pubescent; nutlets ca. 5.5 mm long, base no stipitate, apex with a long erect beak.......................................................................................................3. C. longipetiolata 3b. Leaves ca. 5 mm wide; culms prostrate on the ground; perigynia fusiform, 7–10 mm long, glabrous; nutlets ca. 7 mm long, base with shortly stipitate, apex with a short curved beak...............................................................................................4. C. procumbens

Figures

FIGURE 1. Carex procumbens, A. Habit, B. Inflorescence, C. Lateral pistillate spike, D. Staminate glume, E. Pistillate glume, F.Terminal staminate spike, G. Stigmas. Scale bars=1 mm. Photographs by Hu-Biao YANG.

FIGURE 2. Carex procumbens, H. Periginia, J. Nutlet, K. Periginia (SEM), L. Nutlet (SEM); C. longipetiolata, M. Periginia (SEM), L. Nutlet (SEM). Scale bars=1 mm. Photographs by Hu-Biao YANG.

FIGURE 3. Carex procumbens. A. Habit. B. Inflorescence. C. Lateral pistillate spikes. D. Terminal staminate spike. E. Pistillate glume. F. Staminate glume. G. Periginia. H. Nutlet. Drawn by Yu-xi Zhu based on Yang Hubiao 20140228001 (holotype, IBSC!).