Sagenopteris phillipsii are leaves of extinct species of seed ferns.

Sagenopteris phillipsii has narrow, palmately arranged leaves with anastomosing venation

Different organs attributed to the same original plant can be reconstructed from co-occurrence at the same locality and from similarities in the stomatal apparatus and other anatomical peculiarities of fossilized cuticles.

• Sagenopteris phillipsii may have been produced by the same plant as Caytonia nathorstii (ovulate organs) and Caytonanthus arberi (pollen organs).