23. Cinnamomum japonicum Siebold, Verh. Batav. Genootsch. Kunsten. 12: 23. 1830.
天竺桂 tian zhu gui
Cinnamomum acuminatifolium Hayata; C. chekiangense Nakai; C. chenii Nakai; C. insularimontanum Hayata; C. japonicum var. chekiangense (Nakai) M. B. Deng & G. Yao; C. macrostemon Hayata var. pseudoloureiroi (Hayata) Yamamoto; C. pedunculatum Nees; C. pseudoloureiroi Hayata.
Evergreen trees, 10-15 m tall, 30-35 cm d.b.h. Branchlets red or red-brown, slender, terete, very glabrous, scented. Leaves subopposite or those on upper part of branchlet alternate; petiole red-brown, robust, concave-convex, glabrous; leaf blade gray-green and opaque abaxially, green and shiny adaxially, ovate-oblong or oblong-lanceolate, 7-10 × 3-3.5 cm, leathery, glabrous on both surfaces, triplinerved, midrib extending to leaf apex, with a few additional veins on upper part of leaf blade, basal lateral veins oblique, arising 1-1.5 cm above leaf base, with a few additional veins outside, sometimes a pair of slightly conspicuous additional veins arising from leaf base, midrib and lateral veins elevated on both surfaces, transverse veins and veinlets finely foveolate abaxially and conspicuously densely reticulate adaxially, base broadly cuneate or obtuse, margin entire, apex acute to acuminate. Panicle axillary, 3-4.5(-10) cm, branched, apex of branch bearing a 3-5-flowered cyme; peduncle 1.5-3 cm, glabrous. Pedicels 5-7 mm, glabrous. Flowers ca. 4.5 mm. Perianth tube obconical, short, ca. 1.5 mm; perianth lobes 6, ovate, ca. 3 × 2 mm, acute, glabrous outside, villous inside. Fertile stamens 9, included; filaments ca. 2 mm, those of 3rd whorl each with 2 orbicular-reniform glands near middle, others glandless; anthers ovate-elliptic, obtuse, 4-celled; cells introrse (of 1st and 2nd whorls) or extrorse (of 3rd whorl). Staminodes 3. Ovary ovoid, ca. 1 mm, slightly puberulent; style a little longer than ovary; stigma discoid. Fruit oblong, ca. 7 × 5 mm, glabrous; perianth cup in fruit shallowly cupuliform, apex very open and up to 5 mm wide, entire or shallowly dentate on margin, base abruptly contracted into a slender stalk. Fl. Apr-May, fr. Jul-Sep.
Evergreen broad-leaved forests on low hills, near seashores; 300-1000 m. Anhui, Fujian, Jiangsu, Jiangxi, Taiwan, Zhejiang [Japan, Korea].
Cinnamomum macrostemon Hayata (Icon. Pl. Formosan. 3: 160. 1913) was described from Taiwan. Although Li (Woody Fl. Taiwan, 204. 1963) regarded it as a synonym of C. japonicum, the present authors prefer to leave it unplaced because they have seen no material.
The leafy branchlets and bark contain volatile oil, which is a source of perfume. The fruit kernel contains oil and fat, which are used in soap manufacture. The wood is hard and durable and is used for house construction and furniture.