Sagenopteris

Sagenopteris has two pairs (making four in total) of palmately arranged leaflets with anastomosing venation and a prominent midrib, which are all attached to the apex of a petiole. Mature leaves are generally lanceolate to oblanceolate, the edges are generally entire (smooth), slightly undulating, and occasionally lobed or dentate (toothed), the cuticle is somewhat thick, and the stomata are only present on the underside (abaxial surface) of the leaflets. According to Xu et al. 2024, the stomata are characterised by "guard cells with a flat surface and a sunken region around the aperture; guard cells typically surrounded by a single ring of weakly modified neighbouring cells in an anomocytic arrangement". == Species ==

The following species have been described: In a 2024 review, only 5 species, Sagenopteris acuminata (which was designated the lectotype species), S. colpodes, S. hallei, S. phillipsii and S. pualensis were considered valid. == Distribution ==

Fossils of Sagenopteris have been registered in: ;Triassic Argentina, China, Germany, Greenland, Italy, Japan, Kyrgyzstan, the Russian Federation, Sweden, Tajikistan, Ukraine, United States (Virginia, Virginia/North Carolina). ;Jurassic (to Cretaceous) Afghanistan, Antarctica, Argentina, Azerbaijan, Belarus, Canada (British Columbia, Yukon), China, Colombia (Valle Alto Formation, Caldas), Georgia, Germany, Greenland, India, Iran, Italy, Japan, Kazakhstan, Kyrgyzstan, Mexico, Peru, Poland, Romania, the Russian Federation, Tajikistan, Turkmenistan, Ukraine, the United Kingdom, United States (Alaska, Montana, Oregon/Idaho), and Uzbekistan. ;Cretaceous Spain, Belgium, Canada (British Columbia and Alberta), Greenland, the Russian Federation, and the United States (Montana). == References ==