Metacladophyton

Name

Metacladophyton

Rank

Genus

Authors (Pub.)

Wang Zh. Geng B.-Y.  

Publication

A new Middle Devonian plant: Metacladophyton tetraxylum gen. et sp. nov. [1997/10]

Journal

Palaeontographica

Volume

243

Issue

4-6

Page number

93

Year

1997

Fossil Status

stems (with sporangia)

Type

Metacladophyton tetraxylum

Diagnosis

Main axis nodose. Rhizome with roots, giving rise to aerial branching system having three orders of branches, the first order branches being whorled or near whorled, the second one opposite or near opposite, the third alternate. Ultimate units dichotomous with recurved tips. Fertile branching system similar to the vegetative one except for terminal, erect, paired sporangia. Elliptical sporangium with longitudinal dehiscence. Spores trilete and of one size. Dissected steles with eight arms, usually in V-shaped form in transverse section. Mesarch maturation. Protoxylem group, occasionally two, at tip of each arm. Protoxylem lacunae or peripheral loops present. Mature stem possessing secondary xylem with uniseriate rays. Bordered pits scalariform, elliptical or circular on all walls of the metaxylem tracheids and secondary xylem tracheids. Decussate pit apertures. During branching, C-shaped traces 'depart in a whorled order, each trace with a protoxylem group at its two ends. Strands splitting and fusing at central part of the vascular tissu& as traces depart.