2007(2):183-194.
DOI: 1
CSTR:
Abstract:
A lycopsid plant with preserved morphology and anatomy is described from the Huangjiadeng Formation (Frasnian) of Hubei Province. Its stems are slender. The leaf bases are spindle in shape, and arranged in helices. Leaves are persistent and spiny. This plant bears distal cones. Sporophyll is spoon-like and lanceolate in form,with spines along its margins. Sporangia are circular or elliptical in surface view. In anatomy, the stem has a solid strand of exarch primary xylem. Protoxylem tracheids, composed of annular or helical elements, appear as minute ridges on the stele periphery. Metaxylem tracheids are composed of scalariform elements, showing no connecting "Williamson's striations" between the bars. The shared characteristics of the present plant and Longostachys (Zhu,Hu and Feng) Cai and Chen, from the upper Middle Devonian (Givetian) of Hunan Province, lie in linear and spiny leaves, spindle-shaped and helically arranged leaf bases, spoon-like or lanceolate sporophylls; further more, the dimensions of leaves, leaf bases and sporophyll are also quite alike. However, they show differences in some anatomical characteristics; the present plant bears no secondary xylem, no pith, and no connecting materials between thickened bars of metaxylem tracheids. The preserved characteristics, however, are incomplete for establishing a new species.We temporarily assign our specimens to cf. Longostachys sp.
