Mnesithea formosa (R.Br.) de Koning & Sosef

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

2. Mnesithea formosa (R.Br.) de Koning & Sosef — Fig. 2

Mnesithea formosa (R.Br.) de Koning & Sosef in Veldkamp et al. (1986) 288. — Rottboellia formosa R.Br.(1810) 206. — Manisuris formosa (R.Br.) Kuntze (1891) 779. — [ Rottboellia formosa var. typica Domin (1915) 261, nom. inval.]. — Type: R. Brown 6157 (holo BM; photo BRI, K; K, MEL, NSW).

Rottboellia formosa R.Br. var. pilosissima Domin (1915) 261. — Type: Domin II 1910 (holo PR; photo BRI; K, L, NSW), W Queensland, Cloncurry .

Rottboellia formosa R.Br. forma subglabra Domin (1915) 261. — Type: Domin I 1910 (holo PR; photo BRI; K), Queensland, Townsville, Castle Hill .

Plants annual. Culms 0.4–0.8 m long, glabrous to pilose or with scattered bulbous-based bristles. Cataphylls absent. Nodes glabrous to setose. Sheaths hairy to setose, margin pilose to ciliate. Ligule 0.8–2 mm long, margin ciliolate to setose. Contra-ligule absent. Blades flat to folded, 7–18 cm by 2–4 mm, margins pectinate at base, hairy on both sides, setose behind the ligule, smooth. Peduncles solitary or paired, glabrous to hairy. Spatheoles 4–7 cm long. Spikes 2–4 cm by 1.8–3 mm. Spikelets paired. Joints 3.2–3.6 mm long, hairy all over. Sessile spikelets 3–3.2 mm long (incl. callus), shorter to about as long as the joint. Callus hairy. Lower glume convex, ovate to ovate-oblong, hairy, apex rounded, not winged, coriaceous, smooth, yellowish to greenish yellow, 9–11-nerved, lower part at keel smooth; upper glume concave, ovate to ovate-oblong, 2.8–3 mm long, glabrous to ciliolate along the infolded margin, 4–6-nerved, nerves anastomosing, apex acute. Lemmas ovate to ovate-oblong, 2.1–2.6 mm long, apex rounded, ciliolate along the margin; first lemma epaleate, 2.4–2.6 mm long, 3–4-nerved; second lemma 3-nerved. Second palea ovate-oblong, 1.8–2.1 mm long, 2–3-nerved, margin ciliolate. Anthers 1.2–1.4 mm long. Pedicel completely adnate to the joint. Pedicelled spikelets reduced to 2 glumes, laterally flattened, 3.6–5.4 mm long. Glumes chartaceous to coriaceous, margins ciliolate, base winged, apex caudate. 2n =?

Distribution — Malesia: Lesser Sunda Isl. (Kissar, Wetar), New Guinea: Aru Isl., Papua New Guinea (Western, Central); Australia (Queensland, Northern Territory, W Australia).

Habitat — Eucalypt savannahs, dry grasslands, open forest edges, roadside in degraded mixed forest, red sand, clay soils, heavy brown soil, laterite, granite, up to 200 m altitude; a locally common inconspicuous grass of straggling habit.

Notes — For Queensland Domin (1915) distinguished between a var. typica with a forma subglabra and a var. pilosissima based on the density of the pubescence of the plant. This turned out to be a very variable feature and these taxa cannot be maintained.

Differs from the Malesian / Thai congeners by the unique silvery (rarely golden) setose indument of the sessile spikelet.

Figures

Fig. 2 Mnesithea formosa (R.Br.) de Koning & Sosef. a. Sessile spikelet; b. joint and pedicel (all: Pullen 6751, L).