Considerations on Phylladelphia stringata Bronn form the historical Raibl flora

Raibl is a historical Carnian (Upper Triassic) locality in the Alps, famous for its for plants and fishes. Although already known from the 19th century, only a few authors (Bronn, Schenk, Stur, Dobruskina) described and figured the fossil flora. One of the more peculiar components of this flora is represented by some 20 specimens: Phylladelphia strigata Bronn is characterized by relatively large, spatulate to tongue-shaped leaves with a pointed apex and broad basal attachment area. Several ribs run parallel to a putative midrib, apically transversally arranged marginal wrinkles are sometimes present.

When established by Bronn, Phylladelphia was considered a monocot leaf; afterwards Schenk and Stur compared it with sphenophytes. Up to now the botanical attribution of the genus is unclear, although it resembles slightly the problematic plant (putative angiosperm or ancestor??) Sanmiguelia lewisii Brown. Of particular interest is also the bilaterally symmetry of the leaves, indicating that the leaves were probably closed at some point of the life of the plant, perhaps in the juvenile stage.