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Card. Bull. Singapore 69(2) 2017 
which it has been divided are Damrongia Kerr ex Craib, Henckelia Spreng. (including 
Chirita itself), Liebigia Endl., Microchirita (C.B.Clarke) Yin Z.Wang and Primulina 
Hance (Weber et al. 2011a). Each of these genera is much more morphologically 
coherent than was Chirita. Primulina continues to grow in the number of species and 
is in need of revision, Liebigia has been revised as a section of Chirita (Hilliard, 2004), 
Damrongia has been revised for Thailand, its centre of diversity (Puglisi & Middleton, 
2017), Henckelia is being investigated by a number of research groups (Moller, pers. 
comm.; Sirimongkol, pers. comm.), and Microchirita is the subject of this paper. 
Microchirita is found in India, Myanmar, southern China, Thailand, Vietnam, 
Laos, Cambodia, Peninsular Malaysia, Sumatra, Java and Borneo, almost exclusively 
in limestone habitats. As part of his revision of Chirita, Wood (1974) included 18 
species in Chirita sect. Microchirita C.B.Clarke. Of these, Chirita elata Ridl. has 
since been removed to the genus Codonoboea Ridl. (Rafidah et al., 2011) and eleven 
additional species have been described (Punekar & Lakshminarasimhan, 2009; 
Middleton & Triboun, 2013; Rafidah & Haron, 2013; Puglisi et al., 2016). This brings 
the total to 28 species of which 22 have been recorded for Thailand (Wood, 1974; 
Burtt, 2001; Middleton & Triboun, 2013; Puglisi et al., 2016), one mistakenly ( Chirita 
caerulea R.Br. by Wood, 1974), leaving 21 species. This clearly makes Thailand the 
centre of diversity of the genus with 3 A of the known species in the genus found there. 
The lectotype of the genus is Microchirita hamosa (R.Br.) Yin Z.Wang. 
The most characteristic morphological feature of many species of Microchirita 
is the cristate inflorescence consisting of a single row of flower pairs (Fig. 1A). The 
young flowers develop against the base of the lamina. Subsequently the pedicels 
straighten to an upright position when the flowers reach maturity, and bend backwards 
towards the main stem at the fruiting stage. The series of flower pairs appears as a 
crest along the petiole, and often there is tissue melding together the peduncles at the 
base. Wood (1974) interpreted this crest as a single inflorescence whose peduncle is 
fused with the petiole. Weber (1975) instead supported the idea of a system of multiple 
inflorescences generated by an enlarged meristem which is displaced from the axil onto 
the petiole. No attempt was made to characterise the inflorescence in this study, and 
for merely practical reasons we have chosen to refer to a “cristate inflorescence” when 
applicable, without implying the acceptance of Wood’s theory over Weber’s. Some 
species (e.g. Microchirita involucrata (Craib) Yin Z.Wang) have inflorescences which 
do not appear cristate. They consist of one or few well-developed peduncles arising 
from the axillary end of the petiole, each topped by paired bracts (free or fused), and 
culminating in a subumbellate cluster of pedicels (Fig. IB). 
The species of Microchirita are annual or short-lived. The stems are often fleshy 
and green, tinged with purple-brown. Another characteristic feature of Microchirita is 
the leaf arrangement: the basal leaf, the macrocotyledon, is single, although sometimes 
the paired leaf, the much reduced microcotyledon, persists. The subsequent leaves are 
opposite. This general structure may not be apparent in Microchirita mollissima (Ridl.) 
A.Weber & D.J.Middleton and most Malaysian species (Rafidah, 2017). In these the 
internodes are shorter and the leaves more crowded, thereby obscuring the phyllotaxis. 
Also, the inflorescences develop at the axillary end and are less dense. Some species 
