Description from Flora of China
Aesculus chuniana Hu & W. P. Fang; A. lantsangensis Hu & W. P. Fang; A. megaphylla Hu & W. P. Fang; A. polyneura Hu & W. P. Fang; A. polyneura var. dongchuanensis X. W. Li & W. Y. Yin; A. punduana Wallich ex Hiern, nom. illeg. superfl.; A. rupicola Hu & W. P. Fang.
Trees to 32 m tall, to 0.6 m d.b.h. Branchlets glabrous, subglabrous, or puberulent when young. Petiole 8-30 cm, glabrous, subglabrous, or puberulent; leaf blade 5-9-foliolate; petiolules 0.3-1.5 cm (leaflets rarely subsessile), glabrous, subglabrous, or sparsely puberulent and dark glandular when young; leaflet blades oblong-lanceolate to oblong-oblanceolate, rarely lanceolate to oblanceolate or narrowly so, (7-)12-35(-42) × (3-)5-18 cm, abaxially glabrous, or puberulent or pilose on veins when young, base cuneate or broadly so or rounded, margin crenulate to serrulate, apex acuminate to caudate; lateral veins in 17-30 pairs. Inflorescence pale yellow puberulent; peduncle 7-13 cm; thyrse cylindric, (22-)27-45 cm, 5-14 cm wide at base; branches 2-7 cm, 3-11-flowered; pedicels 3-7 mm. Flowers fragrant. Calyx 4-8 mm, abaxially gray or pale yellowish gray puberulent or finely gray velutinous. Petals 4, white or pale yellow, with purple or brown spots, sometimes orange toward base or claw reddish, unequal, 2 spatulate to oblong and 2 oblong-obovate or obovate, 13-22 × 3-7 mm, abaxially gray puberulent or velutinous. Stamens 5-7, 18-40 mm; filament glabrous; anther 1.5-3 mm. Style glabrous, subglabrous, sparsely puberulent, or tomentose. Capsule yellowish brown, ovoid to obovoid, subglobose, or depressed globose, 4.5-5 × 3-7.5 cm, dotted but smooth; pericarp 1.5-2 mm thick after drying. Seed usually 1, brown, globose, subglobose, or depressed globose, 3-7 cm in diam.; hilum white, occupying ca. 1/2 (rarely ca. 1/3) of seed. Fl. (Jan-)Feb-May, fr. Jun-Nov.
Aesculus assamica is a widespread species in the tropical and subtropical monsoon forest zone from NE India (Sikkim) eastward to S China (Guangxi) and N Vietnam. Here belong most of the new species described by Fang (Acta Sci. Nat. Univ. Szechuan. 1960(3): 77-125. 1962), namely A. chuniana, A. lantsangensis, A. megaphylla, A. polyneura (including the more recently described var. dongchuanensis), and A. rupicola, as well as "A. tsiangii" and "A. wangii," which were not validly published because in both cases two specimens were indicated as types (consequently "A. wangii var. rupicola," in FRPS, was not validly published either). These entities differ from each other in only insignificant details and clearly fall within the range of variation of A. assamica. "Aesculus coriaceifolia," also described by Fang (loc. cit.) but not validly published because no Latin description was given and no type was indicated, was already referred to A. assamica by Fang (in FRPS).
"Aesculus khassyana" (Das & Majumdar, Bull. Bot. Surv. India 3: 95. 1961), accepted instead of A. assamica by Wu (Index Fl. Yunnan. 1: 842. 1984), was not validly published because its supposed basionym, "Pavia khassyana" (Voigt, Hort. Suburb. Calcutt. 97. 1845), is a nomen nudum.
Wet forests, broad-leaved forests, semi-evergreen or mixed deciduous/evergreen broad-leaved forests in limestone hills or mountains, subtropical hill forests, mountain forests, open forests, rocks in forests; 100-2000 m. W Guangxi, S Guizhou (Pingtang), SE Xizang, Yunnan [Bangladesh, Bhutan, NE India, Laos, Myanmar, Thailand, N Vietnam].