黑穗醋栗(Ribes nigrum L.)叶柄的结构和维管组织变化的研究

黑穗醋栗叶柄由表皮、薄壁组织和维管束等组成。在个体发育过程中,子叶和初生叶的叶柄各组成部分较简单;成长叶和成熟叶的叶柄组成较复杂,其表面除一层表皮细胞外,还有一层下皮;邻接下皮处有数层厚角细胞;薄壁组织中分布3个分离(近轴端)或连合(远轴端)的维管束;每个维管束的韧皮部外面有数层厚壁细胞,增加叶柄的机械支持作用。在同一叶柄的不同水平切面上,维管束的数目和排列不尽相同。但在同一品种的成熟叶叶柄远轴端与叶片基部相接处的结构特征和维管束排列形状常相同,比较稳定。

STUDIES ON THE STRUCTURE OF THE PETIOLE AND THE CHANGE OF ITS VASCULAR BUNDLE OFB LACK CURRANT(Ribes nigrum L.)

The petiole of black currant (Ribes nigrum L.) consists of epidermis, parenchyma, vascular bundles, etc. Ontogcnctically the structure of the petiole in cotyledons and primary leaves is comparatively simple. The petioloe of growing and mature leaves consists of epidermis, hypodermis, collenchyma and three separate vascular bundles (adaxial end)or a united vascular bundle (abaxial end) in parenchyma. There are some sclerenchymatous cells outside the phloem of each vascular bundle to increase the supporting force of the petiole. The numbers and the arrangements of vascular bundles are different in different level section of the same petiole.But the structural feature and the arrangement of vascular bundles at the abaxial end of the mature leaf petiole of the same species are similar to those of the leaf blade base, which are relatively stable.