Mnesithea thailandica Traiperm & Boonkerd

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 : 289

11. Mnesithea thailandica Traiperm & Boonkerd — Fig. 12

Mnesithea thailandica Traiperm & Boonkerd (in Traiperm et al. 2010) 341, t. 1. — Type: Paisooksantivathana & S. Suutheesorn y1048-82 (holo BK).

Description based on Traiperm & Boonkerd (in Traiperm et al. 2010).

Plants perennial (cataphylls probably present). Culms 0.26 m long. Nodes puberulous. Sheaths hairy. Ligule 0.5 mm long, margin ciliolate. Blades flat, 5–20 cm long, 4–8 mm wide, hairy on both sides. Peduncles solitary. Spikes 6 cm long. Spikelets paired. Joints 2–2.5 mm long, hairy in the lower half. Sessile spikelet callus puberulous. Sessile spikelet 4–5 mm long (incl. callus); spikelets longer than the joint. Lower glume convex, ovate-oblong, hairy, smooth, laterally without small appendages, apex winged. Upper glume boat-shaped, ovate-oblong, 3 mm long, hairy along the keel. First lemma paleate. Anthers 1 mm long. Pedicel free from the joint, 3 mm long, pubescent. Pedicelled spikelets reduced to 2 glumes, dorso-ventrally flattened.

Distribution — Thailand. Northeast: Roi Et (formerly Saket Nakhon): Suwanaphoom District, Nayai, Ban Hang Hoey.

Habitat — Common in rice fields, c. 100 m altitude.

Notes — Only known from the type collection. A request to BK (24 Jan. 2012) for additional data or a loan remained unanswered.

The description above had to be summarised from the publi- cation and is not congruent with the other ones given here. A later visit by the authors to the area showed that it had been converted to industrial development. Differs from the Malesian / Thai congeners in: Ligule 0.5 mm long. Joints 2–2.5 mm long, hairy in the lower half. Upper glume of sessile spikelet hairy along the keel. Most similar is M. laevis var. laevis : 1. Sheaths glabrous to sparsely hairy; blades glabrous or hairy above. Joints 4.4–6.5 mm long. Upper glume of sessile spikelet 3.9–5.1 mm long. Pedicel 4.4–5.8 mm long........

.............................. M. laevis var. laevis 1. Sheaths hairy; blades hairy on both sides. Joints 2–2.5 mm

long. Upper glume of sessile spikelet 3 mm long. Pedicel

3 mm long.......................... M. thailandica

Figures

Fig. 12 Mnesithea thailandica Traiperm & Boonkerd.a. Habit;b. part of inflorescence;c. spikelet pair; d. pedicelled spikelet with pedicel;e. lower glume of ses- sile spikelet. — Reproduced with the kind permission of the Director and the Board of Trustees, Royal Botanic Gardens, Kew from Kew Bulletin 65 (2010) 342.