Rhomboidales

Yang, Hu-Biao, Li, Xiao-Xia, Bai, Chang-Jun, Wang, Wen-Qiang & Liu, Guo-Dao, 2016, Carex concava (Carex sect. Rhomboidales, Cyperaceae), a new species from Hainan, China, Phytotaxa 283 (2), pp. 155-162 : 160

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

Carex concava can be distinguishing from related species of section Rhomboidales in Hainan Island by the following key.

1. Lateral spikes androgynous ............................................................................................................................................................. (2)

- Lateral spikes pistillate.................................................................................................................................................................... (3)

2. Leaves 10–22 mm wide; perigynia 9–10 mm long, glabrous; nutlets, ca. 7 mm long apex abruptly contracted into a slender and erect beak, base curved-stipitate....................................................................................................................................... C. harlandii

- Leaves 8–10 mm wide; perigynia 7–8 mm long, sparsely pubescent; nutlets ca. 4 mm, apex abruptly contracted into a narrowly cylindric curved beak, base not stipitate............................................................................................................................. C. saxicola

3. Lateral spikes with long peduncles more than 5–8 cm; the adaxial side below the constriction deeply concave ............. C. concava

- Lateral spikes sessile or with short peduncles not more than 3 cm; the adaxial side below the constriction flattish ..................... (4)

4. Leaves 10–15 mm wide; culms erect; perigynia ovate-lanceolate, 7–8 mm long, sparsely pubescent; nutlets ca. 5.5 mm long, base not stipitate, apex with a long erect beak .................................................................................................................. C. longipetiolata

- Leaves ca. 5 mm wide; culms prostrate on the ground; perigynia fusiform, 7–10 mm long, glabrous; nutlets ca. 7 mm long, base shortly stipitate, apex with a short curved beak ........................................................................................................... C. procumbens