蜈蚣草的解剖结构与组织化学特征

蜈蚣草（Pteris vittata）是多年生的超积累砷植物，并用于修复受重金属污染的土壤。利用光学显微镜和荧光显微镜来研究蜈蚣草的解剖结构及组织化学特征，以此明确该物种适应干旱岩生环境，以及具有离子超富集作用的特点。结果表明：（1）蜈蚣草孢子体的根状茎、不定根和叶的结构均为初生结构，不定根的结构由内而外包括维管柱、内皮层、皮层、木质化厚壁组织层和表皮。（2）根状茎结构由内而外包括网状中柱、内皮层、皮层、表皮外覆盖的角质层。（3）羽状复叶的总叶柄的结构由内而外包括维管束、内皮层、皮层、厚壁组织层、表皮外覆盖的角质层。叶片为异面叶，表皮内方具厚壁层，叶表皮具角质层，仅下表皮有气孔。（4）蜈蚣草根表皮、皮层与根毛的表面富含果胶，皮层木质化；黄连素离子通透性试验结果显示，根毛、根表皮和皮层滞留大量黄连素离子。综上，植物体的内皮层、木质化厚壁组织层、异面叶和厚的角质层结构说明蜈蚣草适应岩生环境，根具木质化皮层和富含果胶的组织化学特点，以及离子通透性试验表明其与离子超积累功能有关。

Anatomical and Histochemical Features of the Pteris vittata (Pteridaceae)

The perennial fern Pteris vittata（Pteridaceae） is a hyperaccumulator of arsenic and is used for remediation of soils contaminated by heavy metals. In order to identify the characters that the P.vittata sporophyte thrives in xeromorphic rocky environments and hyperaccumulates ions， the brightfield and epifluorescence microscopy were used to investigate the anatomical structures and histochemical features of this species. The results were as follows： （1）The structure of the rhizome， adventitious roots and leaves of P. vittata sporophytes were all primary structures， the adventitious roots had an vascular bundles， endodermis with Casparian band， lignified sclerenchyma layers， cortex， rhizodermis. （2）The rhizomes had a dictyostele， endodermis， cortex， epidermis， cuticle. （3）The stipes had a single vascular bundle with a central endodermis， cortex， sclerenchyma layers， while the epidermis had a cuticle. The pinnae had bifacial mesophyll with palisade tissue and spongy tissue， the epidermis had a cuticle. （4）The surfaces of the rhizodermis and the root hairs were pectin-rich and underlain by a lignified cortex， and permeability tests using a berberine tracer showed that these structures retained large volumes of berberine. In summary， the suberized endodermis， lignified sclerenchyma layers， bifacial mesophyll， and a cuticle， all of which reflect an adaption to xeromorphic rocky environments. The result of the berberine permeability test are consistent with the hyperaccumulation of ions by P. vittata.