Yangopteris ascendens (Halle) gen. et comb. nov., a climbing alethopterid pteridosperm from the Asselian (earliest Permian) Wuda Tuff Flora

Abstract

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Stem Anatomy Confirms Tingia unita Is a Progymnosperm

“…In particular, differing from the present stem, Sigillaria possesses a smaller vascular cylinder relative to the diameter of the whole stem [ 21 , 23 , 24 ]; Asterophyllites has pith surrounded by a number of collateral vascular bundle and each with a conspicuous protoxylem canal (carinal canal) [ 21 ]; Sphenophyllum has a protostelic vascular cylinder with triangular to subtriangular primary xylem in outline; Marattialean fern with pecopterid pinnules is arborescent and has a stem composed of a series of concentric amphicrybral cauline bundles separated by leaf gaps, and enclosed by numerous adventitious roots (root mantle) [ 21 , 25 ]. Sphenopteris and Alethopteris are respectively a herbaceous and semi-self-supporting plant [ 12 , 26 ] and do not have a thick major stem like the specimens in this study. Taeniopteris and Pterophyllum are cycadean or bennettitaleans in affinity, with their major stem producing manoxylic wood based on our preliminary examination.…”