Todea in the context of "Sporangia"

Tree ferns are arborescent (tree-like) ferns that grow with a trunk elevating the fronds above ground level, making them trees. Many extant tree ferns are members of the order Cyatheales, to which belong the families Cyatheaceae (scaly tree ferns), Dicksoniaceae, Metaxyaceae, and Cibotiaceae. It is estimated that Cyatheales originated in the early Jurassic, and is the third group of ferns known to have given rise to tree-like forms. The others are the extinct Tempskya of uncertain position, and Osmundales where the extinct Guaireaceae and some members of Osmundaceae also grew into trees. In addition there were the Psaroniaceae including Tietea in the Marattiales, which is the sister group to all the leptosporangiate ferns.

Other tree ferns include Leptopteris and Todea in the family Osmundaceae, which can achieve short trunks under a metre tall. Osmunda regalis is sometimes considered a tree fern. Fern species with short trunks in the genera Blechnum, Cystodium and Sadleria from the order Polypodiales and smaller members of Cyatheales like Calochlaena, Cnemedaria, Culcita, Lophosoria and Thyrsopteris are also considered tree ferns. The species Ctenitis sloanei (Florida tree fern) from Florida, Mexico, Bermuda and the Caribbean is sometimes called a tree fern. Like all ferns, tree ferns reproduce by means of spores formed on the undersides of the fronds.

The Leptopteris is a small genus of ferns native to the New Guinea, Australia, New Zealand, and the Pacific Islands. They are similar to ferns in the related genus Todea, and were originally included in that genus. However, the very thin fronds of Leptopteris differ from the thick leathery fronds of Todea, and the genera are considered distinct. A probable extinct species, Leptopteris estipularis is known from the Early Cretaceous of India.