Stockmansella
Stockmansella is a genus of extinct plants of the Middle Devonian, fossils of which have been found in north-west Germany. The sporophyte generation consists of prostrate dichotomizing stems up to 10 cm long and around 3mm wide, which at intervals produce narrower smooth upright stems. These bear sporangia on short lateral branches. 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. 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.