A revision of Microchirita in Thailand 
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hairy; blades green above, paler beneath, ovate or lanceolate, 4-16 x 1.7-10 cm, 
1.4- 2.4 times as long as wide, base obtuse to subcordate, apex acute to acuminate, 
dimorphic eglandular indumentum above, more sparsely so beneath, ciliate along the 
margin, margin entire to obscurely toothed, 5-14 pairs of secondary veins, steeply 
ascending, venation slightly sunken above and raised beneath in fresh material, flat 
in dry specimens, tertiary venation lax. Inflorescences cristate, all axes with a dense 
indumentum of white eglandular hairs; peduncles reduced or to 2 mm long, not fused 
with each other; bracts absent; pedicels pale green, 1-6 mm long. Calyx whitish green, 
actinomorphic, tube 0.5 mm, lobes triangular, 11.5-13 x 1.4-1.6 mm wide, apex 
acuminate, margin entire, densely eglandular hairy outside, inside hairy only towards 
the tip. Corolla 16-20 mm long, bright yellow, with a dark reddish brown ring at the 
throat, tube narrow, straight or curved, abruptly widening, lobes spreading, the ventral 
prominent, eglandular hairy outside, papillose inside, especially on the lobes, and with 
larger glands at the base of the upper lobes; tube 14-17 mm long dorsally, 15-18 mm 
ventrally, 14-16 mm laterally between lips; lobes broadly orbicular and imbricate, 
apices obtuse to rounded, margin obscurely crenulate, upper lobes 2.5-4.5 x 4.5- 
6.5 mm, lateral lobes 4-5 x 5-9 mm, ventral lobe 4-8 x 6-11 mm. Stamens arising 
9-10.5 mm above the corolla base; filaments straight, glabrescent or sparsely hairy, 
1.5- 2 mm long, 0.2 mm wide; anthers white, with an indumentum of thick, probably 
glandular, dark hairs dorsally, 1.3-2 x 1-1.1 mm, apically joined by a connective, 
thecae divergent, the apices pointing towards the base of the corolla; staminodes all 
inconspicuous, or only the lateral staminodes present, lateral staminodes 1-9 mm long, 
arising 2.1-7 mm above the corolla base. Disk a small ventral lobe up to a 3/4 ring, 
0.4-0.5 mm high. Pistil c. 12 mm long; ovary c. 5 mm long, 0.7-0.8 mm diameter, 
glabrous at the base, densely covered in white hairs apically; style c. 5.5 mm long, 
hairy, becoming glabrescent towards the top; stigma glabrous or papillose-plumose, 1 
mm long. Fruit 3-4 cm long, slightly curved. Seeds not seen. 
Distribution. Eastern Thailand (Sa Kaeo). 
Habitat. On limestone. 
Provisional IUCN conservation assessment. Endangered EN Blab(iii). This species 
has a very small EOO and AOO, being only known from the Khao Chakan District of 
Sa Kaeo Province. None of the known localities are in protected areas and are subject 
to high human disturbance. 
Additional specimens examined. THAILAND: Sa Kaeo: Khao Chakan, Wat Ratanakiri, 100 
m, 21 Aug 2012, Middleton, D.J. et al. 5581 (BKF, E, P); Khao Chakan Temple, 88 m, 17 Oct 
2010, Staples, G. et al. 1408 (BKF, E, SING); Krabin, Kao Sakan, c. 50 m, 24 Dec 1924, Kerr, 
A.F.G. 9750 (ABD, BK, BM, K [2 sheets]). 
Notes. This plant is easily recognised by its corolla colour pattern: yellow, with a dark 
reddish brown ring at the throat. All other species of Microchirita which have a yellow 
or orange corolla have smaller lateral spots at each side of the ventral corolla lobe. 
