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PHLOEM ANATOMY IN STAUROPTERIS BISERIATA FROM THE PENNSYLVANIAN OF NORTH AMERICA
Author(s) -
Smoot Edith L.,
Wege Mary Vande
Publication year - 1986
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.1537-2197.1986.tb08549.x
Subject(s) - phloem , pennsylvanian , xylem , biology , sieve tube element , anatomy , botany , parenchyma , paleontology , structural basin
Phloem anatomy in the coenopterid fern Stauropteris biseriata is detailed from Lower‐Middle Pennsylvanian coal ball specimens from eastern Kentucky. Axes exhibit a cruciate‐shaped xylem trace in transverse section. Phloem tissue completely surrounds the xylem, but is more extensively developed in the embayments between the xylem arms. Phloem is composed of elongate conducting elements with a few scattered parenchyma cells. Large and small sieve cells are present, with larger ones occurring in the embayments within the primary plane of symmetry of the axes. Large elements are approximately twice the diameter of the smaller sieve elements. Oval sieve areas and pores have been observed on lateral and oblique end walls of both large and small elements. The structure and composition of Stauropteris phloem is discussed in relationship to the available information on phloem anatomy in other fossil cryptogams.