Bretschneidera sinensis Hemsl.

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New Trees

Tree to 20 m, 1 m dbh. Bark greyish brown. Leaves deciduous, alternate, imparipinnate, green above and glaucous-green below, 25–75 cm long; leaflets 7–15, elliptic to oblong, 6–26 × 3–9 cm, leathery or papery, margins entire, apex acute to acuminate; petiole distinct, 10–25 cm long, swollen at base; petiolules to 1 cm long; lateral veins in 8–15 pairs per leaflet. Inflorescences terminal, erect and racemose, 20–36 cm long. Flowers hermaphrodite, 3–5 cm diameter; calyx large and cupular, 3.2 cm diameter, with five shallow teeth; petals five, free, white to pink, darkening with age, with longitudinal pink or red streaks, 1.8–2 × 1–1.5 cm, upper petal larger, covering the deflexed stamens and style. Fruit a capsule, 3–5.5 × 2–3.5 cm, warty and ellipsoidal to globose. Seeds red, 1.5–2.5 × 1.2–1.8 cm. Flowering March to September, fruiting August to April (China). Lu & Boufford 2001. Distribution CHINA: Fujian, Guangdong, Guangxi, Guizhou, Hubei, Hunan, Jiangxi, Sichuan, Yunnan, Zhejiang; LAOS (?); MYANMAR (?); TAIWAN; THAILAND; VIETNAM. Habitat Forested areas between 300 and 1700 m asl. USDA Hardiness Zone 8–9. Conservation status Endangered. Illustration Lu & Boufford 2001, Ronse de Craene et al. 2002; NT176.

Despite being a very ornamental tree with a wide distribution, Bretschneidera seems to have been introduced to the West only in the early 1990s – by Piroche Plants, Pitt Meadows, British Columbia (motto: ‘We boldly grow what no one has grown before’), although there have been later introductions since. It remains exceedingly rare, with only a handful of specimens in cultivation. Perhaps the best are two in the David C. Lam Asian Garden at the University of British Columbia. When seen in 2004 the larger specimen was about 3 m tall, forming a single straight stem with a tuft of leaves (75 cm long) at the top, but apparently growing well and vigorously in the shade of the huge conifers that form the spectacular setting for this collection. These plants were obtained from Piroche in 1997. At the JC Raulston Arboretum in North Carolina, however, it acts more like a herbaceous perennial; having been cut down by hard frosts, the largest of several shoots was only 1.3 m tall when seen in June 2006, although growing vigorously. This specimen was received in 1993 from Piroche, and is planted in full sun. At Tregrehan it has grown extremely slowly – less than 30 cm in three years (T. Hudson, pers. comm. 2005). It has recently become available in the Dutch nursery trade (M. Zwaan, pers. comm. 2007).

Interest in Bretschneidera derives from its extremely attractive flowers and handsome pinnate leaves. The flowers appear in early summer and are white with pink or reddish veins, looking in photographs like a narrow Aesculus inflorescence. It is curious that such a striking tree should have evaded the horticultural net for so long.

In consequence of its extreme rarity in cultivation, little can be said about its requirements, but a Chinese Ministry of Culture website (China Culture 2003) gives some useful information about its ecological needs. According to the anonymous author of this report, it is a subtropical species, growing in fertile acidic soil, in conditions where it experiences frost but not excessive heat. It germinates in shade, and is a successional emergent, tolerating shade as a young plant and eventually ‘escaping’ to the canopy and beginning to flower. It is said to be deep-rooted and wind-resistant, giving a fine quality of attractive timber. All these characters suggest that it will perform best in the mildest, moister areas of our region: the trees in Vancouver would seem to be ideally sited. Peter Wharton (pers. comm. 2006) wrote: ‘The key to growing this species is siting it in undisturbed native forest soils with semi-shade, where the high forest canopy is naturally thinning or can be thinned. Copes well with root competition, as one would expect. Open sunny sites with man-made soils kill this plant very effectively!’ Wharton also reported that the Vancouver specimens are proving tolerant of long dry spells without rainfall or irrigation. Bretschneidera may remain a rare tree but is one that should be attempted where such conditions can be provided.

Genus

Bretschneidera

Other species in the genus