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白背柳 |
中文名:白背柳 学 名:Salix balfouriana 界:植物界 门:被子植物门Angiospermae 纲:双子叶植物纲Dicotyledoneae 目:杨柳目 Salicales 科:杨柳科Salicaceae 属:柳属Salix 种:白背柳 |
白背柳(bái bèi liǔ,学名:Salix balfouriana),为双子叶植物纲、杨柳科、柳属的植物,为中国的特有植物。分布于中国大陆的云南等地,生长于海拔2,800米至4,000米的地区,常生长在山坡及灌丛中,目前尚未由人工引种栽培。 [1]
白背柳形态特征
白河柳 灌木或小乔木,高可达5米。当年生枝被绒毛;二年生枝无毛或稍有毛,红黑色。芽黑褐色,有毛。
叶椭圆形、椭圆状长圆形或倒卵状长圆形,长6-8(12)厘米,宽2-4厘米,先端钝或急尖,扭转,基部圆形或宽楔形,上面无毛或沿脉上有短柔毛,深绿色,下面密被绒毛,幼叶常杂生锈色绢毛,成熟叶的毛逐渐脱落,下面白色,上年的落叶上面呈灰褐色,全缘,萌枝叶长可达18厘米,边缘有腺齿,开花时叶很小。
花序先叶开花或与叶同时开放,长2-(4)厘米,粗6-10毫米,花序梗短或无,基部无叶或有1-2小叶;雄蕊2,花药黄色,稀红色,花丝2/3有柔毛;苞片倒卵状长圆形,先端圆截形或有缺刻,外面上部红黄色,被柔毛,上部和边缘的毛较长,内面无毛或稍有毛;
腺体2,背生和腹生,有时分裂;子房卵状圆锥形,无柄,有的呈红紫色,密被柔毛,花柱长,2深裂,柱头2裂;苞片同雄花;腺体1,腹生。
果序长可达8厘米,其梗也伸长;蒴果长5.5毫米,近无毛。花期4月下旬-5月上旬,果期6-7月。 [2]
Salix balfouriana Schneid. in Bot. Gaz. 64: 137. f. B. 1-4. 1917; Hand.-Mazz. Symb. Sin. 7: 74. 1929; Hao in Fedde, Rep. Beih. 93: 96. t. 37: 74. 1936.——S. forrestii Hao, 1. c. 69. t. 19: 38. 1936, syn. nov.
Shrubs or trees to 5 m tall. Two-year-old branchlets glabrous or slightly pilose; juvenile branchlets reddish black, tomentose. Buds blackish brown, pilose. Leaves very small at anthesis; petiole 1-1.5 cm, pilose; leaf blade elliptic, elliptic-oblong, or obovate-oblong, 6-8(-12) × 2-4 cm, to 18 cm on shoots, glandular dentate, abaxially tomentose, usually rust-colored sericeous when young, when mature glabrescent, whitish, adaxially glabrous or pubescent along veins, dark green, base rounded or broadly cuneate, margin entire or inconspicuously glandular dentate, apex obtuse or acute, contorted; fallen leaves of previous year grayish brown. Flowering precocious or coetaneous. Catkins 2(-4) cm × 6-10 mm; peduncle short to nearly absent, with 1 or 2 leaflets at base or not; bracts obovate-oblong, abaxially reddish yellow distally, downy, ciliate, adaxially glabrous or slightly pilose, apex rounded-truncate or notched. Male flower: adaxial and abaxial glands sometimes divided; stamens 2, free; filaments pilose nearly throughout; anthers yellow, rarely red. Fruiting catkin to 8 cm, with elongated peduncle. Female flower: gland adaxial; ovary reddish purple, ovoid-conical, pubescent, sessile; style long, 2-lobed; stigma 2-cleft. Capsule to 5.5 mm, subglabrous. Fl. Apr-May, fr. Jun-Jul.
- Mountain slopes, thickets; 2800-4000 m. Sichuan, NW Yunnan
白背柳近种区别
本种与白背柳S. balfouriana Schheid.,银背柳S. ernesti Schneid.相似。主要区别为本种叶下面密被伏生的铅灰色绢毛,有光泽,至老叶毛也很少脱落,叶脉不明显,花柱及柱头不扭曲。
白背柳生长环境
生长于海拔2800-4000米的山坡或灌丛中。