Kindly sponsored by a member of the International Dendrology Society.
John Grimshaw (2016)
Grimshaw, J. (2016), 'Stewartia sinensis' from the website Trees and Shrubs Online (treesandshrubsonline.
Deciduous shrubs or trees, 3–11 m. Bark mottled and peeling, in rich buff tones; first year twigs purplish-red, glabrous or villous, winter buds with 3–11 scales. Leaves 5.5–10.5 × 2.5–4.5 cm, elliptic to obovate-elliptic, papery, glabrous above, yellow-green below, with appressed pubescence on lamina and long-hairy on midrib, 7–11 pairs of veins, margin weakly serrate, apex acute to acuminate, base cuneate to rounded; petiole c. 1 cm, purplish red, glabrous or villous, narrowly winged. Flowers solitary; pedicel 0.5–3 cm, pubescent or glabrescent, thickened toward apex; bracteoles persistent, ovate, long ovate, ovate-lanceolate, broadly ovate, or subcordate, 2–2.5 × 1–1.3 cm, leaflike, apex abruptly acute, acuminate, or long acuminate; sepals 1–2 × c. 1 cm, ovate, long ovate, ovate-lanceolate, broadly ovate, or subcordate, leaflike, outside glabrous or basally sparsely pubescent, apex abruptly acute; corolla white, 5–6 cm diameter, lobes 2.5–3 × 1.5–2 cm, broadly obovate, grey sericeous externally, apex rounded; stamens 1.5–2 cm; filaments fused at the base, free parts sparsely hairy; ovary conical, tomentose; style c. 1 cm, glabrous. Capsule conical, 1.5–2 × 1–1.5 cm, tomentose, apex rostrate; columella abortive. Seeds obovate in outline, planoconvex, 6–9 × 4–5 mm, margin narrowly winged. Flowering May–July (China). (Ming & Bartholomew 2007).
Distribution China Anhui, Fujian, northern Guangxi, Guizhou, Henan, Hubei, Hunan, Jiangxi, southern Shaanxi, eastern Sichuan, north-east Yunnan, Zhejiang
Habitat Forest, woodland or mountain scrub, 500–2200 m asl.
USDA Hardiness Zone 5-7
RHS Hardiness Rating H5
Conservation status Not evaluated (NE)
Chinese botanists recognise four varieties: var. sinensis, found throughout the range of the species; var. acutisepala (P.L. Chiu & G.R. Zhong) T.L. Ming & J. Li, from Zhejiang, with particularly large and pointed bracts and sepals; var. brevicalyx (S.Z. Yan) T.L. Ming & J. Li, from lower altitudes in Zhejiang, bracts and sepals more rounded; var. shensiensis (Hung T. Chang) T.L. Ming & J. Li, from Henan, southern Shaanxi and possibly southern Gansu, with all young growth densely hairy (in the other varieties it is glabrous to glabrescent).
A key to the varieties is provided by Flora of China. How distinct these taxa are is unclear, and no evidence of them being recognised as separate entities in cultivation has been found. Stewartia gemmata Chien & Cheng is considered to be a later synonym of S. sinensis by Spongberg (1974) though it sometimes still appears in catalogues – possibly labelling S. rostrata.
Bean wrote: ‘…introduced by Wilson about 1901 from W. Hupeh, when collecting for Messrs Veitch. It is not remarkable for its flowers, but few hardy trees have a more beautiful bark, which, in its summer condition, is as smooth as alabaster and the colour of weathered sandstone; in autumn it turns purple, later brown, and peels away in translucent scrolls, exposing the fresh inner coating.’ (Bean 1981). The bark colouring persists into old age, as 300 year-old trees in Lushan have been observed to have mottled bark by Philippe de Spoelberch (in Hsu, Boland & Camelbeke 2008). Wild individuals can also become very impressive with age: a sacred tree in the Wudang Shan measured at 15 m × 55 cm dbh has been observed (Del Tredici et al. 1995).
Trees from Wilson’s introduction have made fine specimens in southern England, developing bark just as described by Bean. The tallest recorded, a tree noted for its great beauty, is at Trewithen, Cornwall, and was 14 m in 2004 (Johnson 2011), but similarly sized trees have been known across the southern counties and in Ireland – a tree at Mount Usher, Co. Wicklow, was 12 m in 2000. It is cultivated in North America and continental Europe, but de Spoelberch (2002) has observed that young plants are somewhat tender and this may limit its usefulness in areas with severe winters. Warm summers are appreciated, but not essential; trees planted in 1975 in the sheltered but cool conditions of Ray Wood at Castle Howard, North Yorkshire, have formed specimens about 5 m tall with spreading canopies and flower freely in early summer (pers. obs.). Autumn colour varies but Dirr (2009) comments that in his experience it is usually ‘subdued reddish’ rather than anything more spectacular; in his opinion this is ‘the best!’ for bark, and concludes ‘should be pursued by discriminating gardeners’.
S. sinensis seems to have been introduced to North America in 1934 when seeds from the Sun Yat Sen Memorial Park, Nanjing, were received by the Arnold Arboretum (Spongberg & Fordham 1975); they were labelled S. monadelpha, however and their true identity was not revealed until the 1970s. Some North American plants labelled S. sinensis are believed to be hybrids, possibly S. × henryae (Hsu, Boland & Camelbeke 2008) – a careful comparison and keying-out is needed.
A seedling raised at Polly Hill Arboretum from Arnold Arboretum seed sown in 1984, first flowering in 1993, with 4 cm diameter flowers. It had been selected from the seedling batch before flowering, as an ‘outstanding’ specimen, with ‘rosy’ autumnal colour. The name means ‘beautiful tree’ (Polly Hill Arboretum).
A variegated clone with speckled leaves; ‘a horticultural curiosity’ according to Hsu, Boland & Camelbeke (2008).