白头树Garuga forrestii W. W. Smith

别名：白头椿;水桐树;毛椿;石山白头树;

科名：橄榄科 Burseraceae

属名：嘉榄属 Garuga

《中国植物志》第43(3)卷021页
  1.白头树（云南禄劝）图版6：10-14
  Garuga forrestii W. W. Smith in Not. Bot. Gard. Edinb. 13: 162. 1921; Hand. -Maza. Symb. Sin. 7:631. 1933, Kalkm. in Blumea 7 (2): 461, fig. 2. 1953; 云南植物志1: 461, 图版45: 10-14. 1977; 云南种子植物名录, 上册826. 1984.——G. yunnanensis Hu in Bull. Fan Mem. Inst. Biol. Bot. ser. 7: 212. 1936.
  落叶乔木，高10-15（-25）米。幼枝密被柔毛，老枝无毛，紫褐色，有纵条纹及明显的叶痕。叶有小叶11-19，幼时密被柔毛，后渐脱落而无毛。小叶近无柄，披针形至椭圆状长圆形，先端渐尖，基部圆形或阔楔形，具浅齿，有圆形小托叶。最下一对小叶小，长约1厘米，常早落；中间一对长7-12厘米，宽2-4厘米，侧脉10-16对；顶生小叶长5-7厘米，具柄，柄长约1.5厘米。圆锥花序侧生和腋生，常多数聚集于近小枝顶部，长14-25（-35）厘米，多次分枝，花轴及分枝纤细，密被直立的柔毛。花白色，长约3毫米，花托杯状，外被绒毛；萼片近钻形，长0.2厘米，两面被毛；花瓣卵形，长约3毫米，外被绒毛；雄蕊近等长；子房无柄，球形，和花柱被疏柔毛，柱头5浅裂。果序有许多不结实的线形花梗。果近卵形，一侧肿胀，横切面多少呈钝三角形，长0.7-1厘米，直径0.6-0.8厘米，两端尖，先端具喙而偏斜一侧，基部有宿存的浅杯状花萼。花期4月，果期5-11月。
  产四川、云南之金沙江谷地及云南之把边江、红河河谷；生于海拔900-2 400米的坡地或山谷杂木林中，为河谷稀树草坡的上层优势树种。

《Flora of China》 Vol. 11 (2008)
Garuga forrestii  W. W. Smith
白头树   bai tou shu
Garuga yunnanensis Hu.
Trees, 10-15(-20) m tall. Branchlets densely pubescent when young, glabrescent, purple-brown, longitudinally striped and conspicuously lenticellate. Leaflets 11-19, nearly without petiolules; blades lanceolate or elliptic-oblong, densely pubescent when young, glabrescent, base rounded or broadly cuneate, margin shallowly serrate, apex acuminate, lowest pairs small, ca. 1 cm, often early deciduous, middle pairs 7-12 × 2-4 cm, with lateral veins 10-16 pairs, terminal leaflet 5-7 cm, with petiolule ca. 15 mm. Panicles 14-25(-35) cm, axillary or lateral, usually crowded toward ends of branchlets, multibranched; rachis and branches slender, densely tomentose. Flowers white, ca. 3 mm; receptacle cup-shaped, abaxially tomentose. Sepals nearly subulate, ca. 2 mm, hairy on both surfaces. Petals ovate, ca. 3 mm, abaxially tomentose. Stamens nearly equal. Ovary sessile, globose; style sparsely pubescent; stigma shallowly 5-lobed. Infructescence with many linear pedicels without fruits. Drupe nearly ovoid, one side dilated, 7-10 × 6-8 mm, ± obtusely deltoid in cross section, attenuate at both ends, apex with a point, base with persistent shallowly cupular calyx. Fl. Apr, fr. May-Nov.
● Sparse forests in dry hot valleys; 700-2400 m. SW Sichuan, Yunnan.