5. Homalium ceylanicum (Gardner) Bentham, J. Linn. Soc., Bot. 4: 35. 1859.
斯里兰卡天料木 si li lan ka tian liao mu
Blackwellia ceylanica Gardner, Calcutta J. Nat. Hist. 7: 452. 1847; Homalium balansae Gagnepain; H. bhamoense Cubitt & W. W. Smith; H. ceylanicum var. laoticum (Gagnepain) G. S. Fan; H. hainanense Gagnepain; H. laoticum Gagnepain; H. laoticum var. glabratum C. Y. Wu.
Trees, 6-30(-40) m tall, buttressed; bark smooth to coarse; branchlets brown, angular to terete, puberulous to glabrous. Stipules linear-lanceolate, 1.5-3 mm, glabrous or glabrescent, early caducous; petiole 5-12 mm, glabrous or finely hairy; leaf blade variable in shape and size, elliptic to oblong, rarely obovate, excluding acumen 1.5-2.5(-3) × as long as broad, 6-18(-20) × 2.5-8(-9) cm, thinly leathery to thickly papery, abaxially pubescent with appressed short hairs or glabrous, adaxially glabrous or ± glabrescent, midvein raised abaxially, flat or impressed adaxially, lateral veins 7-10 pairs, raised abaxially, base acute with concave sides, acute-cuneate, or subrounded, margin serrate-crenate to practically entire, teeth apices obtuse, leaf apex acute to rounded, contracting (sometimes very abruptly) to an acumen to 1 cm. Inflorescence axillary, racemose, pendulous, 5-20(-30) cm; rachis sparsely to very densely, pale grayish brown shortly pubescent; bracts narrowly triangular, minute, to ca. 2 mm, papery, sparsely hairy, caducous. Pedicels 1-3 mm, articulate at or above middle, densely puberulous to appressed shortly pubescent. Flowers numerous, in fascicles of 3 to ca. 20, sometimes very crowded along rachis, reddish or whitish, 4-6-merous, 2.5-3 mm in diam. at anthesis, fragrant. Calyx tube 0.5-1.5 mm, sparsely to densely pubescent, hairs whitish, appressed, short (0.1-0.2 mm); sepals linear-oblong or spatulate, 0.5-2 × 0.3-0.5 mm, apex acute, indumentum outside as for calyx tube, inside slightly denser, margin densely ciliate, hairs spreading, whitish, length less than 1/2 to 1 × sepal width. Petals whitish or pinkish, ovate-oblong or spatulate, 0.8-2 × ca. 0.6 mm, both surfaces densely appressed whitish pubescent, sometimes more so than sepals, margin densely white-ciliate, apex obtuse. Disk glands truncate at apex, hairy. Stamens 4-6; filaments 2-3 mm, glabrous; anthers ca. 0.4 mm. Free part of ovary gray pubescent; placentas 4-6, each with 3-6 ovules; styles 4-6, free nearly to base, 1-2 mm, sparsely hairy at base; stigmas capitate to slightly peltate. Mature fruit not seen. Fl. Jan-Nov, fr. Feb-Dec.
Sparse or dense forests of mountain valleys, forest margins, rain forests, evergreen broad-leaved forests, along streams, in forested ravines, on gentle slopes; 400-1200 m. Guangdong, Guangxi, Hainan, Hunan, Jiangxi, SE Xizang, S Yunnan [Bangladesh, India, Laos, Myanmar, Nepal, Sri Lanka, Thailand, Vietnam].
Homalium ceylanicum is cultivated for ornament, and its wood is used commercially. Yu (in Fu & Jin, China Pl. Red Data Book 1: 304-305. 1992) gave H. laoticum var. glabratum as an accepted taxon and categorized it as vulnerable. They noted it as a rare and valuable timber tree, with small, scattered populations under threat from felling and bush fires. Natural regeneration is poor and seed set is low (despite prolific flowering).
Homalium ceylanicum is treated here in a wide sense as a highly polymorphic species within which various elements show intergrading variation in indumentum, leaf size, and raceme length. Indian floras recognize also H. ceylanicum subsp. minutiflorum (Kurz) Mitra, with H. ciliatum N. Mukherjee in synonymy. Wu Zhengyi (pers. comm., 2005) recommended recognition of H. bhamoense at species level, with a new species to accommodate plants from Xizang. Resolution of the H. ceylanicum complex requires a study across its entire range. Material with mature fruit is apparently scarce. Verdcourt (in Dassanayake & Clayton, Rev. Handb. Fl. Ceylon 10: 219. 1996) recommended a field study to investigate fruit production.