榆树
分类:植物科普
榆树 Ulmus pumila L.
榆树叶片
榆树果期
榆树树皮
落叶乔木，高达25米，胸径1米，在干瘠之地长成灌木状；幼树树皮平滑，灰褐色或浅灰色，大树之皮暗灰色，不规则深纵裂，粗糙；小枝无毛或有毛，淡黄灰色、淡褐灰色或灰色，稀淡褐黄色或黄色，有散生皮孔，无膨大的木栓层及凸起的木栓翅；冬芽近球形或卵圆形，芽鳞背面无毛，内层芽鳞的边缘具白色长柔毛。叶椭圆状卵形、长卵形、椭圆状披针形或卵状披针形，长2-8厘米，宽1.2-3.5厘米，先端渐尖或长渐尖，基部偏斜或近对称，一侧楔形至圆，另一侧圆至半心脏形，叶面平滑无毛，叶背幼时有短柔毛，后变无毛或部分脉腋有簇生毛，边缘具重锯齿或单锯齿，侧脉每边9-16条，叶柄长4-10毫米，通常仅上面有短柔毛。花先叶开放，在去年生枝的叶腋成簇生状。翅果近圆形，稀倒卵状圆形，长1.2-2厘米，除顶端缺口柱头面被毛外，余处无毛，果核部分位于翅果的中部，上端不接近或接近缺口，成熟前后其色与果翅相同，初淡绿色，后白黄色，宿存花被无毛，4浅裂，裂片边缘有毛，果梗较花被为短，长1-2毫米，被（或稀无）短柔毛。花果期3-6月（东北较晚）。
分布于东北、华北、西北及西南各省区。生于海拔1 000-2 500米以下之山坡、山谷、川地、丘陵及沙岗等处。长江下游各省有栽培。也为华北及淮北平原农村的习见树木。朝鲜、前苏联、蒙古也有分布。
边材窄，淡黄褐色，心材暗灰褐色，纹理直，结构略粗，坚实耐用。供家具、车辆、农具、器具、桥梁、建筑等用。树皮内含淀粉及粘性物，磨成粉称榆皮面。掺合面粉中可食用，并为作醋原料；枝皮纤维坚韧，可代麻制绳索、麻袋或作人造棉与造纸原料；幼嫩翅果与面粉混拌可蒸食，老果含油25％，可供医药和轻、化工业用；叶可作饲料。树皮、叶及翅果均可药用，能安神、利小便。
阳性树，生长快，根系发达，适应性强，能耐干冷气候及中度盐硷，但不耐水湿（能耐雨季水涝）。在土壤深厚、肥沃、排水良好之冲积土及黄土高原生长良好。可作西北荒漠、华北及淮北平原、丘陵及东北荒山、砂地及滨海盐硷地的造林或“四旁”绿化树种。
Trees, to 25 m tall, d. b. h. to 1 m, deciduous. Bark dark gray, irregularly longitudinally fissured. Branchlets yellowish gray, glabrous or pubescent, unwinged and without a corky layer, with scattered lenticels. Winter buds dark brown to red-brown, ± globose to ovoid; inner bud scale margin usually white ciliate. Petiole 4-10 mm, pubescent; leaf blade elliptic-ovate to elliptic-lanceolate, 2-8 × 1.2-3.5 cm, abaxially pubescent when young but glabrescent or with tufts of hairs in vein axils or sometimes a few hairs on midvein and in forks of secondary veins, adaxially glabrous, base obliquely to symmetrically obtuse to rounded, margin simply or sometimes doubly serrate, apex acute to acuminate; secondary veins 9-16 on each side of midvein. Inflorescences fascicled cymes on second year branchlets, appearing before leaves. Perianth 4-lobed, margin ciliate. Samaras whitish tan, ± orbicular to rarely broadly obovate or elliptical, 1-2 × 1-1.5 cm, glabrous except for pubescence on stigmatic surface; stalk 1-2 mm; perianth persistent. Seed at center of samara or occasionally slightly toward apex but not reaching the apical notch. Fl. and fr. Mar-May. 2n = 28.
Slopes, valleys, plains; 1000-2500 m. Gansu, Hebei, Heilongjiang, Henan, Jilin, Liaoning, Nei Mongol, Ningxia, E Qinghai, Shaanxi, Shandong, Shanxi, Sichuan, Xinjiang, Xizang [Korea, Mongolia, E Russia; C Asia].
This species is cultivated throughout China.
