A deciduous tree up to 65 ft high in the wild, with a trunk up to 9 ft in girth; young shoots densely clothed with short, yellowish brown hairs, glabrous the second year. Leaves roundish heart-shaped, often obliquely so, terminated by a short abrupt point, margins evenly and distinctly toothed, 11⁄2to 4 in. long, rather less wide, glabrous above except for some minute hairs on the chief veins, grey-green and densely clothed with starry down beneath, especially on the midrib and the seven to nine pairs of lateral veins; there are also tufts of down in the vein-axils; leaf-stalk 1 to 2 in. long, downy. Flowers solitary or three on the cyme, yellowish white, the bract narrowly oblong, clothed with starry down, especially at the back, the flower-stalk united with it as far as the middle. Petals 1⁄3 in. long, 1⁄10 in. wide. Fruits egg-shaped, 3⁄8 in. long, distinctly five-angled, covered with a pale close felt.
Native of W. Szechwan, China, where Wilson discovered it in 1903 and introduced it at the same time. It is quite hardy and grows well at Kew, where it has flowered and borne fruit. Its most distinctive character perhaps is the woolliness of its shoots and general downiness, to which the specific name (‘unshorn’) refers. Examples recorded are: Wakehurst Place, Sussex, 51 × 21⁄4 ft (1974); Colesbourne, Glos., 67 × 41⁄4 ft and 66 × 53⁄4 ft (1971).
As admitted in Plantae Wilsonianae, this species may be no more than a local variant of T. chinensis Maxim., a species not differing much from the above description, except that the young shoots are glabrous and the fruits more strongly ribbed. It is of wide range, from Kansu through Szechwan to Yunnan. The lime described by Schneider under the name T. chinensis is not the true species but T. tuan var. chinensis.