酢浆草叶片及花朵感夜运动的结构机制

为了解酢浆草(Oxalis corniculata)叶片和花朵的感夜性，采用半薄切片方法对其叶枕和花托进行形态解剖学观察。结果表明，黑暗处理酢浆草后叶片完全闭合，3枚叶片以叶轴为轴线向下紧贴闭合。黑暗处理8 h花瓣完全闭合并螺旋成束状，花萼紧贴螺旋的花瓣但不发生螺旋。叶片张开时屈肌侧皮层薄壁细胞收缩，伸肌侧皮层薄壁细胞膨大。叶片闭合时屈肌侧皮层细胞膨胀，伸肌侧表皮细胞和3～5层外皮层薄壁细胞收缩。花朵闭合时，花托基部的5个维管束收缩合并成2束明显分离的维管束群，且存在细胞壁加厚的现象；花托角隅处细胞膨胀。叶枕中的屈肌和伸肌细胞的收缩或膨胀控制酢浆草叶片的感夜运动，酢浆草花朵的感夜运动主要与花托基部的维管束群和花托角隅处细胞的膨大和收缩有关。

Structural Mechanism of Nyctinastic Movement in Leaves and Flowers of Oxalis corniculata

In order to understand the nyctinasty of leaves and flowers of Oxalis corniculata, the leaf pillows and receptacles were studied by semi-thin section. The results showed that the leaves were completely closed after dark treatment, and three leaves were tightly closed downward with the leaf axis as the axis. The petals were completely closed and spiraled into bundles under dark for 8 hours, and the calyx clung to the spiral petals but did not spiral. The cortical parenchyma cells on the flexor side contracted and the parenchyma cells on the extensor side expanded when the leaf was opened. When the leaf was closed, cortical cells on the flexor side expanded, epidermal cells on the extensor side and parenchyma cells on the 3-5 layers of outer cortex contracted. When the flower closed, the five vascular bundles at the base of the container contracted and merged into two distinct vascular bundles, and the cell walls were thickened. Cells swell at corner of receptacle. Therefore, the contraction and expansion of flexor and extensor muscle cells in the leaf occipital control the nocturnal motion of the leaves of O. corniculata. The nocturnal motion of flowers is mainly related to the enlargement and contraction of the vascular bundles at the base of the receptorum and the cells at the corner of the receptorum.