五种红树植物叶片结构的比较研究

Comparative study on leaf structures of five mangrove plants

以木榄(Bruguiera gymnorrhiza)、桐花树(Aegiceras corniculatum)、拉关木(Laguncularia racemosa)、海芒果(Cerbera manghas)、杨叶肖槿(Thespesia populnea)五种红树植物为材料,采用常规石蜡切片法对它们的叶片横切面结构进行显微观察,比较真红树植物和半红树植物叶片结构的特点及变化规律,研究红树植物叶对盐浸环境的适应性。结果表明:除杨叶肖槿为异面叶、掌状网脉外;拉关木为等面叶、羽状脉,其它三种植物为异面叶、羽状网脉;五种材料具4级叶脉,3级、4级脉具明显维管束鞘。木榄、桐花树、拉关木、杨叶肖槿1级脉为半周韧无限维管束,海芒果1级脉为外韧无限维管束。五种材料叶肉具有分泌腔,除海芒果外,具有含晶体细胞;木榄、桐花树有内皮层,拉关木有贮水组织;桐花树、海芒果有含单宁细胞;桐花树、拉关木、杨叶肖槿有盐腺。这五种植物的叶片结构体现出不同植物对盐浸环境适应性的特征。相比较而言,真红树植物的特化结构较半红树植物多。

With five mangrove plants Bruguiera gymnorrhiza,Aegiceras corniculatum,Laguncularia racemosa,Cerbera manghas and Thespesia populnea as the research materials,conventional paraffin sectioning was used to observe the crosscutting structures of leaves. To examine these five plants＇ adaptabilities to salty environments,the characteristics and changes in leaf structures of truer mangrove plants and semi-mangrove plants were compared. Experimental results were as follows： Except for T. populnea and Laguncularia racemosa,the other three species had bifacial leaves and were pinnately veined while Thespesia populnea had bifacial leaves and was palmately veined; Laguncularia racemosa had isobilateral leaves and was pinnately veined. Leaves of all these five species had four veins,and tertiary veins and the fourth veins had obvious bundle sheaths. The primary veins of Bruguiera gymnorrhiza,Aegiceras corniculatum,Laguncularia racemosa,Thespesia populnea had semi-amphicribral open bundles and Cerbera manghas had collateral open bundles. The mesophyll of the five species had secretory cavity,in addition to C. manghas,the other four species had crystal cells. Bruguiera gymnorrhiza,Aegiceras corniculatum had endodermis. Laguncularia racemosa had aqueous tissue. Aegiceras corniculatum,Cerbera manghas had tannin cells. Aegiceras corniculatum,Laguncularia racemosa,Thespesia populnea had salt glands. The structure characteristics of leaves in these five species showed the adaptability characteristics of different plants to the salt leaching environment. In comparison,truer mangrove plants have specialized structures more than semi-mangrove plants.