new lycopsid from the Upper Devonian of Hubei Province, China

A new herbaceous lycopsid,Hubeiia dicrofolliagen. et sp. nov., is described from the Xiejingsi Formation (Late Devonian) of Hubei Province, China. Its stems are isotomously dichotomized. Leaf bases are circular or slightly elliptical in shape and arranged in low helices or alternating pseudowhorls....

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Bibliographic Details
Published in:International journal of plant sciences 2005-05, Vol.166 (3), p.519-531
Main Authors: Xue, J, Hao, S, Wang, D, Liu, Z
Format: Article
Language:English
Subjects:
Anatomy
Botany
Classification
Epidermal cells
Flowers & plants
Genera
herbaceous plants
Hubeiia dicrofollia
Leaves
new geographic records
new species
paleobotany
Phloem
plant anatomy
plant morphology
Plant tissues
Stems
Taxa
Tracheids
Xylem
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Description
Summary:A new herbaceous lycopsid,Hubeiia dicrofolliagen. et sp. nov., is described from the Xiejingsi Formation (Late Devonian) of Hubei Province, China. Its stems are isotomously dichotomized. Leaf bases are circular or slightly elliptical in shape and arranged in low helices or alternating pseudowhorls. Persistent leaves are divided into four segments as a result of two successive dichotomies. It has a solid exarch primary xylem strand. Protoxylem tracheids are composed of annular elements that appear as ridges on the stele surface. Metaxylem tracheids are scalariformly thickened and between thickened bars present vertical threads generally termed “Williamson’s striations.” Primary phloem forms a narrow band, four to eight cells thick, surrounding the stele. The cortex is relatively thick, possibly two zoned. Leaf traces are mesarch; they depart directly from protoxylem points and pass through the cortex with a stable oblique angle. This plant possesses a distinctive combination of characters, i.e., forked leaves in morphology and scalariformly thickened tracheids with Williamson’s striations in anatomy, and therefore it is designated as a new stem form genusHubeiiagen. nov. Taxonomically, it is assigned to Protolepidodendraceae.
ISSN:1058-5893
1537-5315
DOI:10.1086/428629