Ten different types of microproblematic structures occur on the surfaces, and in epidermal and hypodermal cells of fern pinnules preserved in the Late Pennsylvanian Grand-Croix cherts from France. These include thick-walled spheres, some with a prominent exit site, aggregations of variously sized spheres that may be surrounded by a membrane or sheath, a cylindrical structure composed of polygonal compartments, and branched hyphae/filaments with intercalary swellings protruding from a small opening in the surface (probably a stomatal pore). Some of the structures likely were produced by some fungal group, and may represent (resting) spores, microsclerotia, and conidiophores. The affinities of the others, and sometimes even their biological nature, remain difficult to determine. Nevertheless, documenting these structures is important because it provides the first indication for vascular plant leaves that were colonized by different types of organisms in a late Paleozoic ecosystem.

中文翻译：

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来自法国上宾夕法尼亚州的蕨类植物小叶的微问题内生菌和附生菌

十种不同类型的微问题结构出现在表面上，以及保存在法国宾夕法尼亚州晚期 Grand-Croix 燧石中的蕨类小叶的表皮和皮下细胞中。这些包括厚壁球体，一些具有突出的出口位置，可能被膜或鞘包围的各种大小球体的聚集体，由多边形隔室组成的圆柱形结构，以及从小开口突出的中间膨胀的分枝菌丝/细丝在表面（可能是气孔）。一些结构可能是由某些真菌群产生的，可能代表（静止的）孢子、微菌核和分生孢子梗。其他人的亲缘关系，有时甚至是他们的生物学性质，仍然难以确定。尽管如此，