Digitaria mollicoma (Kunth) Henrard (1934: 97)

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 : 262

13. Digitaria mollicoma (Kunth) Henrard (1934: 97) .— Paspalum mollicomum Kunth (1833: 47) .— Paspalum molle J. Presl (1830: 213) , nom. illeg. Type:— PHILIPPINES, Luzon, T. Haenke s.n. (holotype PR; isotypes B†, BM!, MO, W).

Digitaria elevatovenulosa Ohwi (1947: 6) . Type :— SINGAPORE, Shonanto, J. Ohwi 6 (holotype BO!; isotype SING!).

Digitaria elevatovenulosa Ohwi var. glabra Ohwi (1947: 6) .— D. mollicoma (Ohwi) Henrard var. glabra Henrard (1950: 819) . Type:— INDONESIA, Java, Bantam, C.A. Backer 7318 (holotype BO!).

Annual or perennial. Culms decumbent and creeping, 30–40 cm high; nodes pilose. Sheath s 1.2 –3 cm long, densely pilose. Ligules 1–1.2 mm long. Blades linear to lanceolate, 2–5.5 cm by 3–5 mm, chartaceous, both surfaces densely pilose, apex acute. Inflorescences composed of racemes; peduncles glabrous; common axis absent. Racemes 2–3, longest 5–7.5 cm long, digitate; rachis ribbon-like, winged, margins serrulate, 0.7–0.8 mm wide. Pedicels terete to trigonous, glabrous; abscission discoid to cupuliform. Spikelets ternate, homomorphous, lanceolate, 2.1–2.3 long, apex acute; hairs smooth or verrucose with acute apex. Lower glume 0.1–0.2 mm long, membranous. Upper glume elliptic to slightly lanceolate, 1.9–2 mm long, chartaceous, apex acute, pubescent between nerves but with glabrous interspaces beside the midnerve or pubescent only on the margins, nerves 3. Lower lemma lanceolate, as long as the spikelet, chartaceous, apex acute, pubescent with glabrous interspaces beside the midnerve or pubescent only on the margins, nerves 7, equidistant. Upper lemma lanceolate, 2–2.1 mm long, coriaceous, apex acute or apiculate, yellowish. Anthers 0.6–0.8 mm long, yellowish. Caryopsis ellipsoid, 0.9–1 mm long, yellowish. ( Figures 4G & 4H )

Distribution: — China, Taiwan, Thailand, Malaysia, Singapore, Indonesia, Philippines, Papua New Guinea.

Selected specimens examined: — PENINSULAR MALAYSIA. Penang: 17 February 1919, M. Nur Bin Mohamed Ghose 4757 ( K, SING). Selangor: 15 October 1946, H. J. Simpson s.n. ( SING). THAILAND. Mae Hong Son: Pang Ung, 19 October 2009, B. Boonsuk 164 ( BK, BKF, KKU, QBG) ; ibid., 2 December 2011, B. Boonsuk 609 ( BK, BKF, KKU, QBG) .

Ecology: —Open areas, moist sandy to clayey soils; elevation 0–1,200 m.

Conservation status: —Although only small numbers of specimens of D. mollicoma have been collected and deposited in herbaria, it occurs in several countries from China to SE Asia. We assess this species as LC according to IUCN (2012) criteria.

Note: Digitaria mollicoma is distinguished in having densely pilose leaves and sheaths with a few racemes. Its spikelets are lanceolate and pubescent with smooth or verrucose hairs.

Figures

FIGURE 4. SEM micrographs of spikelets of some Digitaria species from mainland SE Asia. A–D. D. heterantha (from M. Norsaengsri 2827): A–B. subsessile spikelets; A. lower glume and lower lemma, lower lemma with closed nerves and slit-like interspaces between nerves; B. upper glume. C–D. pedicelled spikelets; C. lower glume and lower lemma, lower lemma pubescent with sericeous hairs and bristles; D. upper glume. E–F. D. longiflora (from B. Boonsuk 370): E. lower glume and lower lemma; F. upper glume. G–H. D. mollicoma (from B. Boonsuk 164): G. lower glume and lower lemma; H. upper glume. I–J. D. petelotii (from B. Boonsuk 98): I. lower glume and lower lemma; J. upper glume. K–L. D. pusilla (from A.F.G. Kerr 11198): K. lower glume and lower lemma; L. upper glume. Scale bar: A–D. & G–J. = 400 μm, E–F. & K–L. = 200 μm.