A revision of Microchirita in Thailand 
245 
Karaket, R, Triboun, P., Kawatkul, U. & Meeboonya, R. 4526 (holotype BKF; isotypes 
E [E00629480], P [P00966764], QBG). (Fig. 8) 
Herb to 60 cm tall with elongated stem runners. Habit caulescent, internodes c. 8 
cm (only one seen). Stems succulent, green, sometimes tinged with reddish, glabrous 
or glabrescent; branches sometimes arising from the petioles. Leaves opposite, apart 
from the basal leaf; petioles 0.5-2 cm long, green, sparsely eglandular hispid; blades 
mid to dark green above, whitish green beneath, ovate, 5.1-25 x 3.5-19 cm, 1.6-2.6 
times as long as wide, base cordate, apex acuminate, sparsely eglandular hairy above 
and beneath, ciliate along the margin, margin entire, 7-15 pairs of secondary veins, 
steeply ascending, venation sunken above and raised beneath in fresh material, flat in 
dry specimens, tertiary venation laxly reticulate. Inflorescences cristate, peduncles 
reduced or emerging to 10 mm long and sometimes fused together; bracts absent; 
pedicels pale green, 4.5-10 mm long, glabrescent or very sparsely hairy. Calyx green, 
bilabiate, lower lobes completely divided, upper lobes joined for 1-5 mm, lobes 
narrowly lanceolate, 1-6 x 0.8-1.6 mm, apex acuminate and slightly thickened, 
margin entire, sparsely hairy especially at the tip. Corolla 12-18 mm long, white 
with a yellow stripe ventrally inside and violet patches at its sides, lobes white, tube 
narrow, curved, progressively widening, upper lobes spreading, eglandular hairy 
outside, glabrous inside; tube 9-13 mm long dorsally, 9.3-14 mm ventrally, 7.8-14 
mm laterally between lips; lobes broadly orbicular to elliptic, apices rounded, upper 
lobes 2.7-3.5 x 2.8^1.7 mm, lateral lobes 2.8-5 x 4-5.8 mm, ventral lobe 3-4.7 x 
3.8-5.5 mm. Stamens arising 3.3-6.5 mm above the corolla base, filaments straight, 
glabrous, 2.8-3.5 mm long, c. 0.3 mm wide; anthers anthers white or pale yellow, with 
a sparse long indumentum by the insertion, 1.4-2 x 0.8-1.2 mm, apically joined by 
a connective, thecae divergent; staminodes arising c. 3 mm above corolla base, c. 0.3 
mm long. Disk absent or a ventral half ring 0.6-0.7 mm high. Pistil c. 15 mm long; 
ovary 3.5-5 mm long, c. 1 mm diameter, papillose or with sparse hairs in the top half; 
style 6-7 mm long, pubescent; stigma chiritoid, c. 1.2 mm long. Immature fruit green, 
to 5 cm long, c. 1.5 mm diameter, glabrous, straight or slightly curved. Seeds brown, 
narrowly elliptic, acuminate, 0.4-0.5 x c. 0.2 mm. 
Distribution. Northern Thailand. Myanmar. 
Habitat. On limestone in mixed deciduous forest. 
Provisional IUCN conservation assessment. Vulnerable VU Blab(iii). The EOO is 
around 8,000 km 2 , it is known only from fewer than 10 populations, and some of the 
known localities are not in protected areas and subject to disturbance. The assessment 
will have to be reviewed once the distribution in Myanmar is better known. 
Additional specimens examined. THAILAND: Chiang Mai: Chiang Dao, road to Wiang 
Haeng, 610 m, 21 Sep 2008, Middleton, D.J. et al. 4536 (BKF, E); Chiang Dao, Daan Pha 
Woak, 740 m, 20 Aug 1999, Watthana, S. et al. 559 (QBG); Chiang Dao, Kio Phawok border 
