刺槐叶的亚显微结构与耐旱性的关系

刺槐（RobiniapseudoacaciaLinn．）虽然引自北美，但现在已成为西北干旱半干旱地区的主要造林树种。叶片形状为羽状复叶，小叶呈椭圆形，叶面积与体积之比为5．6。叶表面具蜡质壳状、管状毛和鳞片状纹饰。叶片与叶柄被以毛状体；叶背面有浅内陷气孔，具大孔下室。上下表皮细胞外壁具明显的角质层加厚；上表皮细胞呈椭圆形，下表皮细胞呈乳头状；栅栏组织与海绵组织之间界限不明显，栅栏组织较为发达，排列紧密，约2—3层细胞，海绵组织有退化的趋势；中脉和叶柄维管束均有厚壁组织细胞组成的维管束鞘；薄壁组织细胞中含有大量的晶体和淀粉粒，叶片已具有许多旱生特征。

SUBMICROSTRUCTURE AND DROUGHT RESISTANCE OF BLACK LOCUST LEAF

Black Locust (Rohinia pseudoacacia L. ) is one of the main afforestation trees inaridand semi--ary regions of China. It has pinnate leaves and the pinna iselliptic. The ratiobetween the area of leaf surface and the leaf volume is 5. 6. There are crustose andscalelike wax ornamentations on the leaf surface. The leaf blade and petiolule are coveredwith downs. There are stomatal apparatus on the backside of the leaf with a biggerunderetoma room and they belong to shallow--sunken stoma. The outerwalls of the upperand lower epidermis cells have obvious cuticular thickening. Upper--epidermis cells areelliptic and lower--epidermis cells are mammillifom. The dividing line between thepalisade tissue and the spongy tissue in not clear. Well developed palisade tissue has two orthree layers of -cells,and the spongy tissue has a trend of degeneeration. Both mid--veinand petiolule vascular bundles have bundle--sheathes composed of sclerenchyma cells.The parenhyma cells are rich in crystals and starch grains.