Tree to 15 m, 0.2 m dbh. Bark grey. Branchlets smooth. Leaves 7–16 × 3–8 cm, elliptic to oblong, both surfaces glabrous, or with some tomentum on veins, 7–11 secondary veins on each side of the midrib, margins remotely serrate, apex acute to acuminate; petiole 1–1.5 cm long. Inflorescences racemose, ~7 cm long with six to eight flowers. Calyx with dense grey-yellow pubescence, corolla lobes ovate, 2–2.5 cm long, slightly uneven. Capsule hard, woody, cylindrical, obovoid to ellipsoid, 4.5–8 cm long, 3- to 10-ribbed, smooth or slightly pubescent. Flowering March to April, fruiting July to September (China) (Hwang & Grimes 1996).
Distribution China Guangdong, Guangxi, Hunan, Yunnan.
Habitat Dense forest between 100 and 1300 m asl.
USDA Hardiness Zone 8-9
Conservation status Not evaluated (NE)
Taxonomic note Rehderodendron kwangtungense is similar to R. macrocarpum but differs in its precocious flowering and slightly larger corollas (to 1.8 cm long in R. macrocarpum), and in the stamens being equal to or shorter than the corolla (slightly longer in R. macrocarpum).
Rehderodendron kwangtungense was described by Krüssmann (1986) as being the ‘most decorative species’ of the genus, but also as being not in cultivation. Unfortunately it has to be said that this may still be true, as a number of plants at Tregrehan thought to be this species turned out to be Halesia [Perkinsiodendron] macgregorii when they flowered (T. Hudson pers. comm. 2007). It is closely related to R. macrocarpum. Another tree at Tregrehan, originating in northern Vietnam, is now flowering, however, and appears to fit all the key characters of R. kwangtungense – although this species is not recorded from Vietnam by Hwang & Grimes (1996).
There seems to be a very high level of diversity of Rehderodendron in northern Vietnam, with all the Chinese species except R. gongshanense Y. C. Tang being found in close proximity in a number of locations within the Hoang Lien Son mountains, and it is conceivable that other undescribed taxa could be present, in this region and in the neighbouring trans-border forests close to Yunnan (P. Wharton pers. comm. 2008).