2. Croton mangelong Y. T. Chang, Guihaia. 3: 172. 1983.
曼哥龙巴豆 man ge long ba dou
?Croton oblongifolius Roxburgh (1832), not Delile (1812); ?C. roxburghii N. P. Balakrishnan (1962), not Wallich (1840).
Trees up to 10 m tall; indumentum of appressed peltate scales; branches with dense scale-glands, these gradually deciduous. Petiole 1-3.5 cm; leaf blade elliptic, 10-14 × 4-6 cm, papery, both surfaces olivaceous, only abaxial surface with sparse scales, base broadly cuneate to rounded, base of midrib with 2 abaxial discoid glands, margins glandular-serrate, apex mucronate, mucro obtuse; lateral veins 10-13. Inflorescence terminal or axillary, 15-30 cm, many flowered. Male flowers to 5 mm in diam.; sepals 5, ovate, or ovate-oblong ca. 5 mm, with dense scale-glands; petals oblong, slightly larger than sepals, densely woolly; stamens 10-15, 2-3 × as long as sepals. Female flowers: sepals 5, long triangular, ca. 2 mm; petals 5, linear-oblong, ca. 2 mm; ovary ovoid, puberulent; styles 3, bifid almost to base and spreading. Capsules subglobose, ca. 1 × 0.9 cm. Fl. Jan-Mar, fr. Jul-Oct.
● Dense forests; 500-600 m. S Yunnan (Gengma) [see comment below].
Croton mangelong is very closely related to, possibly conspecific with, the widespread species currently known as C. roxburghii N. P. Balakrishnan, which otherwise lacks a legitimate name. If this is true it would extend the distribution of C. mangelong to Bangladesh, Cambodia, India, Laos, Myanmar, Thailand, and Vietnam.
There has been confusion with Croton persimilis Müller Argoviensis, a much smaller-leaved species restricted to S India and Sri Lanka, and both with species 22 of this account, C. laevigatus, and with C. delpyi Gagnepain, from Indochina, Malaysia, and Thailand, which have stellate hairs rather than the membranous scales characteristic of C. mangelong.