Istchenkophyton

Name

Istchenkophyton

Rank

Genus

Authors (Pub.)

Broushkin A. B. Gordenko N. V.  

Publication

Istchenkophyton filiciforme gen. et sp. nov., a new small vascular plant with thick cuticle from the Devonian of Voronezh Region (European Russia) [2009/12]

Journal

Paleontological Journal

Volume

43

Issue

10

Page number

1203

Year

2009

Parent Taxon

[Phylum] Lycopodiophyta

Fossil Status

stems

Type

Istchenkophyton filiciforme

Diagnosis

Axes thin, round or elliptical in cross section. Branching typically frequent, regular, pseudomonopodial, with laterals alternating in two rows, opposed or orientated at angle to each other. Length of internodes and laterals complexity decrease distally. Main axes (first order) more robust, with long internodes, bear lateral branching systems, principal branching of which occurs in plane more or less perpendicular to that of main axis. Primary axes of lateral branching systems (second order) with short internodes; first ramifications (third order) of each secondary axes depart in one and the same direction in relation to first order axis. Further branching of lateral branching systems occurs usually in the same general plane and manner, with catadromous first ramifications (fourth and all subsequent orders); in distal parts occasionally present nearly isotomous branching in different planes. Axes apices are coiled on dorsal side. Vascular strand (axes of first and second orders) slightly elliptical and stout. Xylem centrarch; protoxylem strand in cross section distinctly elongated (elongation coincides with axis branching plane) and comprises spiral tracheids. Metaxylem massive, composed of tracheids with scalariform and, more rarely, circular bordered pits. Xylem strand encircled by variable in thickness zone of poorly preserved cells, apparently corresponded to phloem or possibly also to inner cortex, composed of thin-walled prosenchymatous elements. Outer cortex of elongated relatively thick-walled cells, with prominent intercellular spaces. Epidermis one-cell thick, consists of cells similar to those of outer cortex; covering cells longitudinally elongated, with strongly cutinized anticlinal walls. Cuticle very thick, resistant to maceration; cutinization of axes often irregular. Over the stomatal pore, cuticle abruptly attenuates, forming conical depression. Stomata relatively rare, more or less regularly spaced over entire surface of axes, orientated longitudinally or, more rarely, oblique. Stomatal apparatuses anomocytic; guard cells bean-shaped or, more rarely, baculiform and slightly sunken relative to ordinary epidermal cells. Stomatal aperture well cutinized.