Stockmansella

Stockmansella is a genus of extinct plants of the Middle Devonian (Eifelian stage, around ), fossils of which have been found in north-west Germany. The sporophyte generation consists of prostrate dichotomizing stems (axes) up to 10 cm long and around 3mm wide, which at intervals produce narrower smooth upright stems. These bear sporangia (spore-forming organs) on short lateral branches (sporangiophores). The prostrate stems have bulges from which rhizoids form. Both prostrate and upright stems have a central strand of conducting tissue which contains simple tracheids, so that "Stockmansella" is a vascular plant.
The genus was created by Fairon-Demaret for fossil forms previously assigned to "Taeniocrada" but which differ in having single lateral sporangia. (She initially gave the genus the name "Stockmansia", but this had already been used for a genus of ferns.) The form genus "Sciadophyton" is thought to be the gametophyte stage of several early land plants, including "Stockmansella", although as these forms have only been found as compressed fossils, their morphology is not entirely clear.
In 2004, Crane et al. published a cladogram for the polysporangiophytes, in which "Stockmansella" is placed in the Rhyniaceae, sister to all other tracheophytes (vascular plants).