Citrus ichangensis Swingle in J. Agric. Res. 1: 4. 1913 excl. descr. fructus & in Citrus Ind. 1: 388. 1967; Bhattacharya & Dutta, Class. Citrus Fr. Assam 80. 1956.

Shrubs or small trees, up to 5 m high; young twigs angular, glabrous, spinous; spines sharp, stout, ca 3 cm long, often wanting in flowering twigs. Leaves unifoliolate, up to 12 cm long; petioles broadly winged, 3.5 - 5 x 1.5 - 2 cm; wings oblong-spathulate,tapering at base, crenate along margins, rounded at tip; leaflet blades ovate-lanceolate, rounded or abruptly blunt at base, acuminate or, more or less caudate at apex, emarginate at tip, slightly crenate along margins, ca 5 x 2 cm; pedicels ca 3 mm long. Flowers solitary, axillary, bisexual, subglobose in bud. Sepals 5, orbicular, thick, ciliolate along margins. Petals 5, oblong, ca 20 x 8 mm, white. Stamens 20, free or rarely polyadelphous. Ovary depressed-globose, 7 - 9-locular; style short, thick, caducous; stigma globose, as large as ovary. Fruits small, oblong with tapering ends, 3 - 5 cm across, lemon yellow; surface smooth, finely papillate; pericarp thin, medium to strongly adherent; mesocarp white, soft, spongy, tasteless; endocarp segments 7 - 9, medium to strongly adherent; pulp-vesicles white, separable, stalked, globose to ellipsoid, obtuse at apex;juice scanty; seeds 22 - 30 per fruit, bluntish at both ends, 12 - 20 x 10 - 18 mm; chalazal cap light brownish; cotyledons white.

Distrib. India: Evergreen forests of the E.Himalayas, Arunachal Pradesh and Nagaland.

S.W. China.

Notes. Fruits are inedible and hence of no commercial value. The plant has been sucessfully employed in evolving cold resistant hybrids such as and yuzu (Swingle 1967: 389 - 390).