There are no active references in this article.
This species has a very unusual distribution: subsp. elegans occurs in Fiji in the southern hemisphere, while subsp. formosana occurs in Taiwan in the northern hemisphere. Their morphology, however, is extremely similar. Owing to its tropical origins, subsp. elegans is unsuitable for outdoor cultivation in temperate areas.
K. henryi Dummer
Tree 7–25 m, 0.5–2 m dbh. Bark rough, furrowed, ±corky, peeling off in square plates. Leaves bipinnate, though the terminal leaflet may be missing, 25–60 ×15–44 cm; leaflets 8–17 on each major division, lanceolate to narrowly ovate or elliptic, 5.5–9.2(–10.2) × 1.3–3(–4.2) cm, glabrous or with scattered hairs on the veins, tufts of hair in vein axils below, margins coarsely serrate, apex long-acuminate to caudate; petiolules 0.4–0.5(–1) cm; rachis glabrous or with short hairs. Inflorescences 30–50 × 20–25 cm, densely pubescent, glandular. Flowers sweetly fragrant; petals acute, four to five, 0.6–0.7 cm long. Capsules ellipsoidal, 3.4–5(–6) × 3–4.6 cm, deep rose-purple when young, brown at maturity. Flowering September to October, fruiting November (Taiwan). Meyer 1976. Distribution TAIWAN. Habitat Forest edges. USDA Hardiness Zone 9–10. Conservation status Not evaluated. Illustration Meyer 1976. Cross-reference S299. Taxonomic note Subsp. elegans has entire or sparsely serrate leaflets, petiolules 0.1–0.3 cm long, and slightly larger, obtuse or rounded petals.
Koelreuteria elegans subsp. formosana was introduced to the United States from Taiwan in 1915 by David Fairchild’s Office of Foreign Plant Introduction. It has proved to be extremely successful in the southern states, especially Florida, and in southern California, where its rounded crown, evergreen leaves, spectacular orange-yellow flowers and inflated pink fruits make it a popular street and specimen tree (Gilman & Watson 1993c). Unfortunately its reproductive prowess has led to it becoming invasive in parts of Florida, Hawaii and Australia. In our area, where it is on the edge of its tolerance, this is not likely to be a problem. It requires a very warm summer to perform well, and is unlikely to succeed in most of northern Europe. A recent introduction by Bleddyn and Sue Wynn-Jones of seed given to them by the Institute of Taiwan Endemic Species in 1999 (BSWJ 7038) has been distributed from Crûg Farm, Gwynedd. The only survivors traced are a couple of specimens struggling along at Tregrehan, where they die back each winter and have not got above a metre in height (T. Hudson, pers. comm. 2007).