ADDITIONS TO “RUBIACEAE OF THAILAND. A PICTORIAL GUIDE TO INDIGENOUS AND CULTIVATED GENERA”
environment/habitat-dependent variability in most of their characters (plant size; number of leaf pairs; leaf shape and size; petiole length; extent of inflorescences; absence or presence additional axillary inflorescences; flower size), often even within one and the same population. “Clarkella siamensis,” previously thought to be a Thai endemic, merely refers to luxuriously developed individuals (“our species is much larger in all its parts than C. nana which it resembles very much in habit;” Craib, 1932: 36); we agree with Lauener & Ferguson (1972) that it does not even need recognition as a variety.
Clarkella nana was previously thought to occur in the Himalayas and Thailand only (Smitinand et al., 1970), but it has since also been recorded from Upper Myanmar and China (Lauener & Ferguson, 1972: 104 & map, fig. 1).
Distribution within Thailand, too, is disjunct (to date, several localities are known from 5 northern provinces, and one locality each from the Southwest and from the Peninsula; as far as Thailand is concerned, the map in Lauener & Ferguson, 1972, is outdated). We are, nevertheless, confident that a thorough survey of Thai limestone vegetation will eventually yield further records which will close the gaps in the presently known, scattered distribution range of this species. Field investigations must, however, be carried out during the rainy season (flowers and fruits are recorded from July to September) because the aerial parts disintegrate and eventually completely disappear in the dry season.
Gardeniopsis Miq., Ann. Mus. Bot. Lugduno-Batavi 4: 250. 1869.
Shrubs or treelets. Leaves opposite, petiolate; stipules interpetiolar, lanceolate. Flowers 5-merous, hermaphrodite, sessile, 1 or 2 in leaf axils or at a series of leafless nodes immediately below the leaves. Calyx with small lobes. Corolla hypocrateriform, lobes contorted to the right in bud, longer than the short tube, curved upwards and inward, never fully spreading. Stamens inserted at the base of the corolla tube, included; anthers linear, basifixed, in a cone-like arrangement. Ovary 2-celled, each locule with a solitary ovule attached to septum; style short, bearing a fusiform stigma. Fruits indehiscent, slightly fleshy, longitudinally ridged or not, 2-seeded, crowned by the persistent, slightly enlarged calyx lobes.
A monotypic genus of somewhat uncertain tribal position, distributed from peninsular Thailand southwards to Peninsular Malaysia, Sumatra and Borneo.— See notes further below.
Gardeniopsis longifolia Miq.,Ann. Mus. Bot. Lugduno-Batavi 4: 250. 1869; King & Gamble [Mat. Fl. Malay Penins. 15], J.Asiat. Soc. Bengal 73: 64. 1904; Ridl., Fl. Malay Penins. 2: 112. 1923; Craib in Fl. Siam. 2: 174. 1934; Wong in Ng, Tree Fl. Malaya 4: 350. 1989. Fig. 2.
Distribution.— PENINSULAR: Surat Thani (Khao Sok National Park), Phangnga, Pattani, Yala.
Notes.— The species is (very) rare in Thailand and only known from a few collections, most of them old. It grows at low altitudes (200–500 m) in evergreen rain forest and appears to favour habitats along streams.