Digitaria ciliaris (Retz.) Koeler (1802: 27)

Boonsuk, Boonchuang, Chantaranothai, Pranom & Hodkinson Abstract, Trevor R., 2016, A taxonomic revision of the genus Digitaria (Panicoideae: Poaceae) in mainland Southeast Asia, Phytotaxa 246 (4), pp. 248-280 : 255-256

4. Digitaria ciliaris (Retz.) Koeler (1802: 27) .— Panicum ciliare Retz. (1786: 16) .— Syntherisma ciliare Schrad. (1806: 160) .— P. sanguinale L. var. ciliare (Retz.) St-Amans (1821: 25) , pro. comb. — D. sanguinali s Scop. var. ciliaris (Retz.) Parl. (1848: 126) , pro. comb.— D. sanguinalis subsp. ciliaris (Retz.) Arcang. (1882: 762) , pro. comb.— Paspalum sanguinale Lam. var. ciliare Hook.f. (1896: 15) .— D. marginata Link var. ciliaris Hook.f. ex Ridley (1925: 214) . Type:— CHINA, Guangdong, Guangzhou, H.P. Wennerberg s.n. (lectotype LD), designated by Blake (1969).

Panicum adscendens Kunth (1815: 97) .— D. adscendens (Kunth) Henrard (1934: 92) .— D. adscendens Henrard subsp. adscendens Bor (1955: 352) . Type:— MEXICO, F.W.H.A. von Humboldt s.n. (holotype P!; isotypes B! (B-W01663010), BM!).

Digitaria marginata Link (1821: 102) .— Panicum linkianum Kunth (1829: 33) .— P. marginellum Schrad. (1838: 428) , nom. superfl.— Syntherisma marginata (Link) Nash (1912: 154) .— P. sanguinale L. subsp. marginatum (Link) Thell. (1919: 699) .— D. sanguinalis Scop. var. marginata (Link) Fernald (1920: 103) . Type:— BRASIL, Brasilia, Herb. Link 97 (the left-hand specimen of the sheet) (lectotype B), designated by Henrard (1950).

Digitaria pes-avis Buse (1854: 380) .— Panicum pes-avis Hook.f. ex Koord. (1911: 128) .— D. adscendens Henrard subsp. marginata Henrard var. pes-avis Henrard (1950: 552) . Type:— INDONESIA, Java, F.W. Junghuhn s.n. (holotype L-908.92-134; isotype U).

Digitaria henryi Rendle in Forb. & Hemsl. (1904: 323).— Syntherisma henry i (Randle) Newbold (1924: 9). Type:— TAIWAN, A. Henry 1031 (holotype K!; isotypes BM!, P!).

Digitaria abortiva Reeder (1948: 291) . Type :— PAPUA NEW GUINEA, C.E. Carr 11108 (holotype US; isotypes BM!, CANB, L!).

Annual. Culms not robust, small tufted or loosely tufted, ascending to erect, 30–50 cm high, rooting at lower nodes; nodes and internodes glabrous; cataphylls absent. Sheaths 2–3.5 cm long, densely setose. Ligules 1.5–1.8 mm long. Blades linear, 4.5–10 cm by 5–10 mm, apex acuminate, margin serrate and sinuate at one side, both surfaces scaberulous with hairs. Inflorescences composed of racemes; peduncles glabrous; common axis 0–6 cm long. Racemes 2–6, longest 5–8.5 cm long, digitate or subdigitate; rachis ribbon-like, winged, ca. 1 mm wide, serrate. Pedicels triquetrous, serrate; abscission truncate. Spikelets binate, homomorphous, lanceolate, 2.8–3.5 mm long; hairs smooth with acute apex. Lower glume triangular, 0.3–0.4 mm long, chartaceous, apex acute to obtuse. Upper glume lanceolate, 2–2.4 mm long, chartaceous, apex acuminate, pubescent between nerves and on margins, nerves 3. Lower lemma lanceolate, as long as the spikelet, chartaceous, apex acute to acuminate, pubescent between nerves and on margins but with broad glabrous interspaces beside the midnerve, nerves 7, inequidistant. Upper lemma 2.5–3 mm long, chartaceous, apex acuminate, not protruding above the lower lemma, yellowish to brownish. Anthers 0.8–0.9 mm long, yellowish to brownish. Caryopsis oblong-ellipsoid, ca. 1.2 mm long, creamy. ( Figures 3I & 3J )

Distribution: —Common, tropical and subtropical regions.

Selected specimens examined: — CAMBODIA. Kampong Cham: July 1953, M. Schmid VN 1472 ( P). LAO PDR. Bolikhamsai: Lak Sao, 8 December 2010, B. Boonsuk & S. Lanosavanh 505 ( KKU, Biology Herbarium NUOL). Champasak: Paksong, 12 October 2010, B. Boonsuk & S. Lanosavanh 434 ( KKU, Biology Herbarium NUOL). MYANMAR. Bago: 20 January 1948, U T. Lwin 454 ( L). Myeik: Tanintharyi river, 3 May 1932, M. P. Khant 13425 ( K). Yangon: Hlawga Lake, 18 June 1947, U T. Lwin 45 ( K). PENINSULAR MALAYSIA. Pahang: Nenasi, 23 August 1935, E. J. H. Corner SF 29884 ( BO, K, P, SING). Penang: 3 July 1941, J. C. Nauen SF 38186 ( SING). Terengganu: Hulu Terengganu, 31 July 2007, T. L. Yao, R. Kiew & A. Julius FRI 57853 ( KEP, L). Johore: 18 December 1932, Z. Teruya 2137 ( SING). THAILAND. Mae Hong Son: Doi Mae U-Kho, 17 October 2009, B. Boonsuk 162 ( KKU). Sakon Nakhon: Phu Phan National Park , 26 September 2010, B. Boonsuk 428 ( KKU). Ubon Ratchathani: Khong Chiam , 11 July 2009, B. Boonsuk 106 ( KKU). Kanchanaburi: Sai Yok , 19 November 1961, K. Larsen 8319 ( C, K) ; Sisawat, 12 January 1926, A. F. G. Kerr 10198 ( BK, BM, K). Sa Kaeo:Aranyaprathet, 10 August 1930, A. F. G. Kerr 19622 ( BM, K). Krabi: Tham Suea Temple, Mueang, 20 August 2010, B. Boonsuk 375 ( KKU). Nakhon Si Thammarat: Kiriwong, Khao Luang National Park , 13 April 2010, B. Boonsuk 254 ( KKU). VIETNAM. Haiphong: 6 October 1921, A. S. Hitchcock 19540 ( P). Danang: 5 October 1921, A. S. Hitchcock 19430 ( P). Binh Thanh: Bien Hoa, 12 January 1914, A. Chevalier 29981 ( P) & 29986 ( L). Lam Dong: 4 May 1954, M. Schmid VN 1745 ( P) .

Ecology: —Open areas, deciduous forests, common weed along roadsides and in old clearings; elevation up to 1500 m.

Conservation status: —We rate D. ciliaris as LC, according to IUCN (2012) criteria due to its large geographic range. In addition to its distribution reported here, it is also abundant throughout the Mainland SE Asia.

Note: — Digitaria ciliaris is a common species in mainland SE Asia. Its spikelets are similar to D. bicornis and D. radicosa in the size and shape of its lower and upper glumes but it differs in having monomorphous spikelets and serrate rachis. This species is first reported for Lao PDR.

Figures

FIGURE 3. SEM micrographs of spikelets of some Digitaria species from mainland SE Asia. A–B. D. abludens (from S. Laegaard & M. Norsangsri 21666): A. lower lemma; B. upper glume. C–D. D. fuscescens (from B. Boonsuk 627): C. lower lemma; D. upper glume. E–H. D. bicornis (from B. Boonsuk 341): E–F. subsessile spikelets; E. lower glume and lower lemma; F. upper glume. G–H. pedicelled spikelets; G. lower glume and lower lemma, sericeous hairs and bristles on lower lemma; H. upper glume. I–J. D. ciliaris (from B. Boonsuk 375): I. lower glume and lower lemma; J. upper glume. K–L. D. nuda (from B. Boonsuk 286): K. lower glume; L. upper glume. Scale bar: A–D = 200 μm, E–L = 400 μm.