Fimbristylis sect. Fuscae Ohwi, J. Jap. Bot. 14: 571, 1938. Type species: F. fusca (Nees) C. B. Clarke; Abildgaardia fusca Nees; Iria fusca (Nees) Kuntze.

Korean name: 납작하늘지기절(Nap-jak-ha-neul-ji-gi-jeol).

Inflorescences with several spikelets. Spikelets compressed, axes persistent. Scales distichously arranged, acropetally deciduous. Styles 3-sided; stigmas 3. Achenes obovate to orbicular, 3-sided, much smaller, smooth or verruculose.

Fimbristylis sect. Fuscae was described by Ohwi (1938) in that it has dark brownish puberulent-scabridulous hairs on glossless scales of spikelets, and much smaller achenes, while F. sect. Abildgaardia (Vahl) Benth. has glossy but hairless scales. This section is characterized by having several spikelets per inflorescence, and much smaller and obovate achenes with smooth or verruculose surfaces. However, sect. Abildgaardia differs from sect. Fuscae in that it has only one (very rarely two) spikelets per inflorescence, and larger and nearly globose achenes with tuberculate surfaces (Kern, 1955, 1974). In addition, sect. Fuscae is distinguished from other sections in the genus except sect. Abildgaardia with somewhat chubby spikelets with spirally arranged scales by having compressed spikelets with distichously arranged scales.

Fimbristylis fimbristyloides (F. Muell.) Druce, Rep. Bot. Soc. Exch. Club Brit. Isles 4: 623, 1917 (Fig. 1).

Abildgaardia fimbristyloides F. Muell., Fragm. 8: 273, 1874; Iria fimbristyloides (F. Muell.) Kuntze, Revis. Gen. Pl. 2: 753, 1891.

Korean name: 바람개비하늘지기(Ba-ram-gae-bi-ha-neulji-gi).

Annuals dwarf, with fibrous roots. Rhizomes absent. Culms tufted and ribbed, ca. 5–15 cm tall, slightly upwardly scabrous at least at top including inflorescence. Leaves linear, with about half size of culms, 3.0–5.0 cm × 1.0–2.0 mm, distinctly curved or falcate to left or right direction, margins upwardly scabrous, apices acute or short acuminate; ligule absent. Inflorescences simple or subcompound, with about 3–10 spikelets, up to 4 cm long, upwardly scabrous; primary branches 3–5, obliquely erect, scabrous, up to 3 cm long; secondary branches very short; involucral bracts 2–5, much shorter than inflorescence, 0.5–2.0 cm × 0.8–1.0 mm, margins scabrous, apices acuminate. Spikelets solitary, lanceolate, strongly laterally compressed, ca. 6–12-flowered, apices acute, 3.0–7.0 × 1.5–2.0 mm, brown; scales distichously equitant, membranous, lanceolate to ovate, 2.2–3.0 × 1–1.5 mm, minutely scabrous at midnerves and margins, prominently midkeeled, apices mucronate. Stamens 2 or 3; anthers yellow, oblong, ca. 0.5 mm long. Ovaries white; styles 3 angled, basally inflated, glabrous, ca. 2 mm long; stigmas 3. Achenes obovate, dully 3-sided, nearly whitish, truncate at bases, 0.6–0.9 × 0.4–0.6 mm, smooth or verruculose, nearly sessile.

Flowering: Aug.–Sep.

Habitat: There are about 100 individuals in open and wet areas on mountain’s foot within plant community of Pinus thunbergii and Eurya japonica near the coastal lines.

Distribution: N Australia, Bhutan, China (southern provinces including Guangdong and Zhejiang), India, Indonesia, Japan (Ryukyu Islands), Korea (southern island in province Jeollanam-do), Malaysia, Myanmar, Nepal, Papua New Guinea, Thailand, Vietnam (from Kern, 1974; Zhang et al., 2010).

Specimens examined: KOREA. Jeollanam-do: Sinan-gun, Amtae-do Island, 17 Oct 2018, S.S. Choi VP1810001 (2 sheets, JNU); 12 Oct 2019, S.S. Choi VP1910001 (2 sheets, JNU).

This taxon was recombined by Druce (1917) into the genus Fimbristylis based on Abildgaardia fimbristlyloides F. Muell., a species described from Rockingham-bay in Queensland, a northeast tropical region of Australia (Mueller, 1874). It is small plant, mainly distributed in tropical and subtropical regions of SE Asia, and is known to grow in China’s Zhejiang and Guangdong provinces and in the open damp areas of Japan's Ryukyu Islands. Koyama (1961) first revealed that F. fimbristyloides is distributed in Korea based on the specimen (KYO) collected by M.K. Park in Mt. Jirisan, but we did not actually see the voucher. However, considering the distribution range of this species in the worldwide, it seems somewhat doubtful that it grows in Mt. Jirisan. Meanwhile, the species is not recorded in the domestic Korean literature, and there is no specimen in any herbaria in Korea, making it unclear about their distribution in Korea. Recently, during a national survey of the natural environment we found a population of F. fimbristyloides, consisting of about 100 individuals on Amtaedo Island, Jeollanam-do, Korea.

Fimbristylis fimbristyloides is similar to the F. ovata (F. sect. Abildgaardia) in that they have laterally compressed spikelets, at least lower scales of spikelets distichously arranged, 3-sided styles, and 3-stigmas. However, they differ greatly from F. ovata in that the plant size is relatively small, the leaves curved to the right or left like a sickle or pinwheel, with several spikelets in one inflorescence, all the scales of spikelets arranged distichously, hairless on the styles, obovate achenes less than 1 mm in length, and nearly stalkless on the achenes (Table 1). The Korean name of F. fimbristyloides was given as a “Ba-ram-gae-bi-ha-neul-ji-gi” based on the characteristics of the leaf bending in one direction like a pinwheel, and the Korean name of the section including this species was named as a “Nap-jak-ha-neul-ji-gi-jeol” considering the fact that all the spikelets were compressed shape. Key to the species of F. fimbristyloides and the closely related species F. ovata are as follows.

1. Spikelets somewhat laterally compressed, all or lower scales distichously equitant at bases.

 2. Culms 5–15 cm tall; leaves distinctly curved or falcate to right or left direction, 1–2 mm wide; inflorescences with ca. 3–10 spikelets; spikelets lanceolate; styles glabrous; achenes less than 1 mm long, nearly sessile· ························ F. fimbristyloides 바람개비하늘지기

 2. Culms 15–40 cm tall; leaves straight and not curved, less than 1 mm wide; inflorescences with 1 (very rarely 2) spikelets; spikelets ovate; styles hairy; achenes ca. 2–3 mm long, distinctly and shortly stalked ·································· F. ovata 쇠하늘지기

1. Spikelets terete; scales spirally imbricate ························· ······························· all other taxa of Korean Fimbristylis