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LYSSOXYLON GRIGSBYI, A CYCAD TRUNK FROM THE UPPER TRIASSIC OF ARIZONA AND NEW MEXICO
Author(s) -
Gould R. E.
Publication year - 1971
Publication title -
american journal of botany
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.218
H-Index - 151
eISSN - 1537-2197
pISSN - 0002-9122
DOI - 10.1002/j.1537-2197.1971.tb09968.x
Subject(s) - cycad , stele , biology , holotype , petiole (insect anatomy) , girdling , gymnosperm , tracheid , paleontology , botany , genus , xylem
Lyssoxylon grigsbyi Daugherty, a petrified stem with petiole bases, was originally described from the Upper Triassic Chinle Formation of Arizona and considered to be a member of the Williamsoniaceae. Investigation of additional material from a similar horizon in New Mexico, together with re‐examination of preparations of the holotype, suggest that the plant, with its monoxylic stele, girdling leaf traces, and bicelled epidermal hairs is a true cycad. Cells of the New Mexico specimens contain structures interpreted as preserved nuclei.