Mnesithea geminata (Hack.) Ridl.

Veldkamp, J. F., Heidweiller, J., Klaauw, M. A. F. van der, Koning, R. de, Kraaijeveld, A. R., Sosef, M. S. M. & Strucker, R. C. W., 2013, A revision of Mnesithea (Gramineae - Rottboelliinae) in Malesia and Thailand, Blumea 58 (3), pp. 277-292 : 280-281

3. Mnesithea geminata (Hack.) Ridl. — Fig. 3

Mnesithea geminata (Hack.) Ridl. (1907) 163. — Rottboellia geminata Hack. (1891) 48. — [ Rottboellia corymbosa L.f. subvar. geminata (Hack.) Roberty (1960) 65, comb. inval.]. — Coelorachis geminata (Hack.) Clayton (1981) 814. — Type: Ridley 11 (holo W; K, SING, fragment in L).

Plants perennial. Culms 0.2–0.4 m long, glabrous to pilose or with scattered bulbous-based bristles. Cataphylls ovate to ovate-oblong, (1.5–)5–15(–56) by 1.5–4 mm, puberulous to ciliate along the margin, apex acute to acuminate or mucronate. Nodes setose. Sheaths hairy to setose, margin pilose to ciliate. Ligule 1–1.2 mm long, margin setose. Contra-ligule absent. Blades flat to folded, 8–22 cm by 2.5–10 mm, margins glabrous to pectinate at base, hairy to glabrescent on both sides, setose behind the ligule, smooth. Peduncles solitary, glabrous to hairy. Spatheoles 5–11 cm long. Spikes 2–3.5 by 1.8–3 mm. Spikelets in the lower part in triads, upwards paired. Joints 4.2–5.4 mm long, glabrous to hairy above. Sessile spikelets 4.8–5.4 mm long (incl. callus), about as long as to longer than the joint. Callus hairy. Lower glume convex, ovate-oblong, hairy to setose, smooth to cancellate, yellowish, 7-nerved, apex winged, lower part at keel smooth; upper glume boat-shaped, ovate-oblong, 3.6–3.9 mm long, 3–4-nerved, nerves not anastomosing, glabrous to ciliolate along the infolded margin, apex acute. Lemmas ovate-oblong, 2.8–3.4 mm long, coriaceous, glabrous to ciliolate along the margin, acute. First lemma epaleate, 2–3-nerved; second lemma 3-nerved. Second palea ovate-oblong, 2.6–2.8 mm long, 2-nerved, glabrous to margin ciliolate. Anthers 1.2–1.4 mm long. Pedicel free from the joint, 3.8–4.6 mm long, glabrous to pubescent, smooth. Pedicelled spikelets reduced to 2 glumes, laterally flattened, 0.8–1.6 mm long. Lower glume chartaceous, margins ciliolate to pubescent, apex winged. 2n =?

Distribution — Malesia: Malay Peninsula (Pahang) and SE Kalimantan (Motley 446: Banjarmasin).

Habitat — Sandy soil at sea level, coconut groove.

Notes — The above account is based on four collections only, all in K: Ridley 11, the type, Ridley 15229, Motley 446 and SF 29882 (Corner). Gilliland (1971: 267) mentioned Thailand, but no specimens were seen .

The first two have joints with two sessile and one pedicelled spikelets (see plate 34a in Gilliland 1971). Motley 446 from SE Kalimantan has some joints with four sessile and two pedicelled spikelets.

This distribution would seem to be one of the indicators of a drought pocket near Banjarmasin.

Differs from the Malesian / Thai congeners in: Culms 0.2–0.4 m long. Joints 4.2–5.4 mm long. Sessile spikelet callus puberulous; lower glume yellowish.

Most similar is M. glandulosa :

1. Culms 0.2–0.4 m long. Sessile spikelet callus puberulous, lower glume laterally without small appendages........

.................................... M. geminata 1. Culms 0.6–1.9 m long. Sessile spikelet callus ciliolate, lower glume laterally with small appendages.... M. glandulosa

Figures

Fig. 3 Mnesithea geminata (Hack.) Ridl. a. Sessile spikelet and joint; b. paired sessile spikelet and pedicel (all: Ridley 11 (type), L).