Tree 6–30 m, 0.6 m dbh. Branchlets covered with stellate tomentum, becoming glabresecent. Leaves papery to leathery, 5–18 × 4–10 cm, elliptic to ovate, upper surface glabrous or with some hairs along the veins, lower surface densely covered in grey stellate tomentum, five to six secondary veins on each side of the midrib, margins entire or apically serrate, apex short-acuminate, base rounded to cuneate; petiole 0.5–1.5 cm long. Inflorescences axillary, when 3–5 cm long, with one to seven flowers, or pseudoterminal, when racemose or paniculate, 3–20 cm long, with 6–23 flowers; pedicels 0.5–1 cm long. Flowers 1.2–1.5 cm long; calyx white-hairy, with irregular small teeth; corolla tube 3–4 mm, lobes five, 10–15 mm, ovate to lanceolate, membranous. Fruit subglobose, 1–1.2 cm diameter, grey stellate-tomentose, splitting by way of three valves. Flowering May to June, fruiting August to October (China). (Hwang & Grimes 1996, Huang et al. 2003).
Distribution Cambodia China Fujian, Guangdong, Guangxi, Guizhou, Hunan, Jiangxi, Yunnan Laos Thailand Vietnam
Habitat Forests between 100 and 2000 m asl.
USDA Hardiness Zone 8-9
Conservation status Least concern (LC)
Resin obtained from various species of Styrax has a long history of use in medicine and as incense. Once obtained from the Mediterranean S. officinalis, these resins are now mostly obtained from S. benzoin Dryander and other Asian species, including S. tonkinensis, and are a surprisingly valuable commodity. In 1996 the trade in ‘gum benzoin’ was worth US$5.2 million to Singapore alone (Kashio & Johnson 2001). Another important use of S. tonkinensis is as a plantation and agroforestry tree, for its rapid growth and quick yield of wood for fuel and pulpwood (Pinyopusarerk 1994). As a natural pioneer, germinating in disturbed forest, S. tonkinensis is ideally suited to plantation conditions, and exhibits at least some hardiness. It is not common in cultivation, but a few trees are growing in the milder parts of our area. At the David C. Lam Asian Garden in Vancouver it flowered profusely at a young age (Wharton et al. 2005), but at Tregrehan, though growing fast to 10 m, it has yet to flower (T. Hudson pers. comm. 2007). In Cornwall it can be semi-evergreen in a mild winter, and with its large leaves requires a sheltered site (Hudson 2004). Plants labelled as S. tonkinensis have been grown at the JC Raulston Arboretum for some time but are almost certainly misidentified (M. Weathington pers. comm. 2008).