Dimeria ornithopoda Trin.

Veldkamp, J. F., 2016, A revision of Dimeria (Gramineae-Dimeriinae) in Malesia with a note on Cymbachne, Blumea 61 (3), pp. 207-214 : 210

4. Dimeria ornithopoda Trin.

Dimeria ornithopoda Trin. (ante 24 Jan. 1820) 167, t. 14; Ridl. (1903) 274 (‘ D. ornithopodioides ’, sphalm.); Honda (1930) 324 [incl. forma typica Hack. ex Honda , nom. inval.]; Bor (1953) 572 (incl. var. genuina , nom. inval.). — [ Dimeria avenacea (Retz.) C.E.C.Fisch.subvar. ornithopoda (Trin.) Roberty (1960) 399, 401, nom. inval.]. — Type: Herb. Trinius 1254.1 (holo LE, IDC microfiche BT-16/1).

Dimeria tenera Trin. (1832) 335. — Dimeria ornithopoda Trin. var. tenera (Trin.) Hack.(1889) 81. — Dimeria ornithopoda Trin. [ var. tenera Hack. ] subvar. typica Hack. (1889) 81, nom. inval. — [ Dimeria avenacea (Retz.) C.E.C.Fisch. subvar. tenera (Trin.) Roberty (1960) 399,402,nom. inval.]. — Lectotype: Chamisso s.n. (LE Herb.Trinius 1255.1, IDC microfiche BT-16/1; iso B, extant?), designated by Teerawatananon et al. (2014: 142).

Didactylon ramosum Zoll. & Moritzi (1846) 100; Buse (1854) preprint: 27; (print) 367; Miq. (1857) 479. — Dimeria ornithopoda Trin. var. ramosa (Zoll. & Moritzi) Hack. (1889) 82; Ridl. (1891) 27 (‘ subramosa ’). — Dimeria ornithopoda Trin. [ var. ramosa ] subvar. typica Hack. (1889) 82, nom. inval. — Dimeria avenacea (Retz.) C.E.C.Fisch. subvar. ramosa (Zoll. & Moritzi) Roberty (1960) 399, 402, nom. inval.]. — Type: Zollinger 351 (holo G; K, L, U, W).

Didactylon simplex Zoll. & Moritzi (1846) 100; Miq. (1857) 480. — Type: Zollinger 1595 (holo P; U).

Dimeria glabriuscula F.M.Bailey (1890) 83. — Type: Bailey 23 (holo BRI;MEL).

Dimeria ornithopoda Trin. subvar. imperfecta Hack. (1889) 82. — Type: Lobb s.n. (holo G).

Dimeria glabra Ridl. (1925) 192. — Dimeria ornithopoda Trin. var. glabra (Ridl.) Jansen (1953) 266. — [ Dimeria avenacea (Retz.) C.E.C.Fisch. subvar. glabra (Ridl.) Roberty (1960) 398, 400, nom. inval.]. — Type: SF 4674 (Burkill) (holo SING; G, K).

Dimeria ornithopoda Trin var. gracillima Bor (1953) 576. — Lectotype: Clarke 21084­B ( K 000245790 ), designated by Teerawatananon et al.(2014: 143).

Annuals. Culms 0.035–0.45(–0.8) m long. Nodes bearded to glabrous. Ligules 0.2–0.5(–1) mm long, margin glabrous, ciliolate, or fimbriate. Leaf blades 1–10(–13) cm by 0.75–3.25 mm, glabrous or sparsely setose. Racemes usually 2, sometimes 3, rarely 4, rachis filiform, terete or triquetrous, 0.7–7(–8) cm long, 0.1–0.5 mm wide, internodes 1–2 mm long, margin scaberulous or ciliate (30 x!). Pedicels 0.1–0.3 mm long. Spikelets 1–3(–4.5) mm long. Callus hairs 0–0.8 mm long. Glume keels not winged. Upper glumes acute, smooth, scabrous, ciliolate, or setose. Awn present or absent, (0–)4–6.5(–10) mm long, incl. 1–3.5 mm long column.Anthers 0.25–0.8 mm long. 2n = 14, 32.

Distribution — India to Japan, N Australia, Malesia: through- out.

Habitat — Sunny, infertile soil, grass fields, road sides, river banks, abandoned rice fields in the dry season, resistant to mowing and grazing, locally abundant, 0–1800 m altitude.

Vernacular name — Bird’s foot grass.

Collector’s notes — Rhizomatous [?]. Culms prostrate, geniculate. Rachis white, margins green. Spikelets purple. Glumes with green veins, sometimes purple tinged. Column purplish brown. Anthers white, yellow. Stigmas white.

Notes — This species is rather variable and Hackel (1889) optimistically and based on only a few specimens distinguished 6 varieties and 4 subvarieties, warning that intermediary forms occur. Bor (1953, 1960) for India distinguished four. Jansen (1953) for Malesia provisionally distinguished three. Duistermaat (2005) regarded them as extremes of a range and I agree. Specimens with spikelets 1–1.5 mm long and anthers up to 0.25 mm have been distinguished as var. gracillima Bor (1953: 576) , and e.g. Teerawatananon et al. (2014: 143, lectotype!), but otherwise they cannot be distinguished. Some collections appear to be just dwarfed forms.

Forms without awns or mucronate ones ( var. glabra ) occur within the same population (see also Ohwi 1965, Duistermaat 2005), but I have not seen mixed collections. BS 336719 (Ramos & Edaño) (SING) from Luzon had spikelets without awns or with short, simple, filiform ones in the same racemes.