Polypodiophyta. The Thelypteridaceae are terrestrial ferns comprising 1-several genera and 900 species concentrated in the tropics but with some temperate representatives. The sporophyte consists of commonly upright rhizomes that often give rise to tufts of pinnate leaves. The rhizomes also typically bear scales and many fibrous roots. Tiny, but rather conspicuous needle-like bristles are found on the leaves, especially along the veins of the lower leaf surface. A cross-section near the base of a leaf petiole reveals two linear, converging vascular bundles that merge into a single "v" or "u" - shaped bundle in the distal portion of the petiole or leaf axis. The sporangia are generally in round sori, each covered with a kidney-shaped indusium.