Am J Bot. 1997 May;84(5):581.
Xylem from roots and rhizomes of two infraspecific taxa of Pteridium aquilinum was studied by means of scanning electron microscopy (SEM). All tracheary elements proved to be vessels. End wall perforation plates were all scalariform, lacked pit membrane remnants in at least the central part of the perforation plate, and varied with respect to width of bars, from wide to tenuous, and with respect to presence of pit membrane remnants. In addition, porose pit membranes on walls that are likely all lateral vessel-to-vessel walls must be considered to be perforations also, although different from those on end walls. Lateral wall perforation plates, hypothesized by one worker on the basis of tylosis presence but denied by another on the basis of light microscopy, were confirmed by demonstration of pores with SEM. In addition, lateral walls of Pteridium vessels bear some grooves interconnecting pit apertures; this feature is newly figured by SEM for ferns. Lateral wall pitting that is not porose may either have striate thickenings of the primary wall or be smooth. Vessel presence and degree of specialization in Pteridium vessels may bear a relationship to the wide ecological tolerances of the genus.
通过扫描电子显微镜（SEM）研究了两种水龙骨属种间类群的根和根茎的木质部。所有的导管分子均为导管。端壁穿孔板均为梯状，在穿孔板的中心部分至少缺乏坑膜残余物，并且在棒的宽度、从宽到细以及坑膜残余物的存在方面存在差异。此外，在可能都是侧向导管-导管壁的壁上的多孔坑膜也必须被认为是穿孔，尽管与端壁上的穿孔不同。侧向壁穿孔板是一位工作者基于侵填体的存在而假设的，但另一位工作者基于光学显微镜观察而否认，通过 SEM 显示孔来证实。此外，水龙骨属导管的侧壁具有一些连接坑口的凹槽；这一特征是通过 SEM 为蕨类植物新绘制的。非多孔的侧壁坑点可能具有初生壁的条纹加厚，或者是光滑的。水龙骨属导管的存在和特化程度可能与该属广泛的生态耐受性有关。
