Vessel-bearing stems of Vasovinea tianii gen. et sp nov (Gigantopteridales) from the Upper Permian of Guizhou Province, China

Permineralized gigantopterid stems of Vasovinea tianii Li et Taylor gen. et sp. nov. were collected from the Upper Permian of Guizhou Province, China. They are slender and bear prickles, trichomes, and compound hooks. Interna lly, the stems have a sparganum cortex. eustele, and secondary xylem. The m esarch protoxylem tracheids have annular to helical thickenings, and metaxy lem tracheary elements have scalariform and/or transversely elongated, bord ered pits, while those of the secondary xylem have scalariform to circular bordered pits. Importantly. the inner part of the secondary xylem has large vessel elements with foraminate-like perforation plates. The hooks and oth er morphological and anatomical characteristics are similar to those found in gigantopterids, suggesting that Vasovinea is a member of the Gigantopter idales. The vegetative plant is reconstructed from permineralized stems and Gigantopteris-type leaves based on the anatomical similarities and intimat e association. The eustele, secondary xylem, and other features support the placement of the order among the seed plants. Ecologically, Vasovinea is s uggested to have been a vine pr liana that used compound hooks to climb amo ng the trees in a Permian tropical rain forest. The occurrence of vessels c ould have been an efficient adaptation to allow the slender stems to conduc t sufficient water to the large Gigantopteris-type leaves.