Eviostachya hoegii Stockmans在中国五通组的首次发现

FIRST DISCOVERY OF EVIOSTACHY A HOEGII STOCKMANS FROM WUTUNG FORMATION IN CHINA

首次描述了Eviostachya hoegii Stockmans的营养部分,通过大量标本的观察,修订了前人有关其生殖部分和解剖部分的描述,并对其生殖部分进行了复原.同意Emberger(1968)的观点,将其归于Eviostachyrales中.

Eviostachya hoegii Stockmans is first collected from the Wutung Formation in China. In this paper, the sterile is first described.Plant with rhizome.Adventitious root observable.Stem with nodes and internodes, generally pseudodichotomously or monopodially branching in three orders. Oval imprints on the surface of internode; no ridge and furrow.Leaves arranged in whorls. Forked leaf generally dichotomizing 4-7 times, with a single vein originating from the base of the leaf and forking several times to provide a veinlet persisting forward to each leaf segment. Wedge-shaped leaves with 6 arranged on one side of node, semicircular in distal margin and straight or slightly concave in lateral ones, with more than 5 veins observable at the base, dichotomizing many times forward, forming the fan-shaped venation.A profound study of the material shows that the reconstruction of cone by Leclercq (1957) may not be completely correct, to which the new emendation and supplementary descriptions are given as follows:(1) Six sporangiophores radially fixed on the node of cone axis.(2) Each sporangiophore trichotomously branching two times, with nine segments of equal length.Based on results of the new method, the inner structure may be considered as:(1) The sterile possibly is the triarch.(2)Besides helical and scalariform tracheid, the sterile contains reticulated and borderedpitting tracheid.In this paper the author agrees with the idea of Emberger (1968) that Eviostachya is treated as an element of the independent order Eviostachyales, which can be described as: Primitive sphenopside, herbaceous, stem with nodes and internodes, pseudodichotomously or monopodially branching; leaves in whorl, cone, bractless. Sporangiophore trichotomously branching two times. Protostele. This order contain one family, Eviostachyaceae; one genus, Eviostachya; and one species, Eviostachya hoegii.