簕仔树的叶片解剖结构研究

Leaf Anatomic Structure of Mimosa bimucronata

关键词:  簕仔树  叶片  解剖结构  适应  入侵植物

Key words:  Mimosa bimucronata  leaf  anatomic structure  adaptation  invasive plant

摘要:

利用石蜡切片技术对簕仔树(Mimosa bimucronata)叶片进行解剖研究。结果表明,簕仔树的叶是异面叶,表皮角质层的角质化程度随发育的进行而增大。叶肉细胞排列紧密,在海绵组织和栅栏组织之间具有贮藏组织。叶脉维管组织发达,具四级叶脉组成脉序,第一级、第二级叶脉类型属半周韧、有限维管束;第三级、第四级叶脉类型属外韧、有限维管束。成熟叶片维管束鞘中有晶体细胞存在。另外,PAS反应显示,在叶片发育初期,海绵组织薄壁细胞、维管束鞘细胞、贮藏组织细胞中有较多淀粉粒分布,以后随着叶片的发育,这些部位细胞淀粉粒的分布越来越少。作为入侵植物,簕仔树叶片结构中角质层的厚度、淀粉粒的分布、栅栏组织与海绵组织紧密的胞间隙与其适合在耐热、耐涝、耐旱的环境生长相适应。

Abstract:

The leaf structure of Mimosa bimucronata is studied by paraffin method under the light microscope.The results show that the leaf of M.bimucronata is dorsi-ventral leaf, and that its cuticle becomes thicker as it grows up.The mesophyll cells are arranged closely and there is storage tissue between palisade tissue and spongy tissue.The vascular tissues of the vein are well-developed and the venation is formed by four veins:the primary and secondary veins are semi-amphicribral, and closed vascular bundles while the tertiary and quaternary veins are collateral, and closed vascular bundles.Crystal cells exist in the vascular bundle sheath of the mature leaf.In addition, the PAS staining shows that in the developmental stage of the leaf, a lot of starch grains are distributed within the parenchyma cells of the spongy tissue, the vascular bundle sheath cells and the storage tissue cells.These starch grains reduce gradually following the development of the leaf.As an invasive plant, the M.bimucronata has adapted the thickness of its cuticle, the distribution pattern of its starch grains and the intercellutar space between its palisade tissue and spongy tissue to withstand high temperatures, flood and drought.