Korea Flora: Deciduous shrub. Height 2m. Winter buds and twigs smooth, a single terminal bud conical and pointed at the tip. Lateral buds opposite, smaller than the terminal bud, 1-3mm long and slightly reddish. Terminal and pseudo-terminal buds present, with accessory buds. Branches  hairless. Leaf scars circular or semicircular, with 7-8 vascular bundle scars. Leaves opposite, broadly ovate, acuminate at apex, cuneate or truncate at base, 8-20cm × 5-13cm in size. Upper surface green and hairless, while the lower surface hairs on the veins and scattered faint glands. Leaf margins smooth or with large teeth. Petioles 3-10cm long with hairs. Flowers cymes at the ends of new branches, with or without hairs. Calyx red, deeply divided into 5 ovate or oblong lobes. Corolla 30mm in diameter, with 5 oblong white petals. Fruit and seeds round, 6-8mm in diameter, blue, initially enclosed by the red calyx before emerging. 

Flowering: Mid-July to mid-August (early June in Gyeonggido)

Fruiting: Late September to mid-October

Distribution: China, Taiwan, northern Philippines, southern Hokkaido to Okinawa in Japan; south of Gangwon-do and Hwanghae-do in Korea.

Ecological characteristics: Light-demanding species, grows in areas with abundant light such as logged areas and roadsides. Fast-growing.

Taxonomic notes: The English version of the Flora of China reports C. cyrtophyllum Turcz. as distributed in south-central China, Malaysia, and Vietnam, as well as in Korea. It has narrower leaves (about 5cm wide, oblong-ovate) compared to C. trichotomum (9-10cm wide, broadly ovate) and slightly smaller flowers (about 2cm long vs. 3cm for C. trichotomum). Such individuals are mainly found in the island regions of Jeollanam-do.

Japan Flora: Large shrub or small tree with rather thick terete branches; leaves membranous, deltoid-ovate, narrowly deltoid, or broadly ovate, 8-15 cm. long, 5-10 cm. wide, gradually acuminate, somewhat rounded at base, obsoletely toothed or subentire, 3- nerved from the base, sometimes thinly pubescent above, pu­bescent beneath especially on nerves, obsoletely glandular* dotted, long-petiolate; cymes in large terminal corymbs; calyx deeply 5-lobed, about 15 mm. long, reddish, the lobes ovate, acuminate, spreading in fruit; corolla-tube 2-2.5 cm. long, the limb 2.5-3 cm. across, white; fruit globose, dark blue, lustrous, 6-7 mm. across, subtended by the persistent spreading calyx. Aug .-Sept.

Hokkaido, Honshu, Shikoku, Kyushu; common. Korea, Manchuria, China, Ryukyus, Formosa, and Philippines.

f. ferrugineum (Nakai) Ohwi. Plant densely pubescent. 

var. esculentum Makino. Leaves cordate, long-acuminate; inflorescence shorter; calyx-lobes narrower. 

var. yakusimense (Nakai) Ohwi. Plant less pubescent and with fewer flowers and thicker lus­trous leaves.