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SECONDARY PHLOEM ANATOMY IN CORDAITEAN AXES
Author(s) -
Taylor Edith L.
Publication year - 1988
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.1537-2197.1988.tb11242.x
Subject(s) - phloem , sieve tube element , biology , cambium , secondary growth , parenchyma , anatomy , vascular cambium , botany , sieve (category theory) , xylem , mathematics , combinatorics
Secondary phloem anatomy in cordaitean axes is described based on Carboniferous coal ball permineralizations from Kansas and Ohio. In both stems and roots, phloem consists of alternating, tangential bands of sieve cells and axial parenchyma. Sieve cells are elongate with tapered end walls and have oval‐rectangular sieve areas on their radial walls. A narrow band of tissue close to the cambium is interpreted as phloem that was probably functional at the time of deposition; the remainder of the extensive secondary phloem presumably represents nonconducting tissue and can be divided into a number of zones based on histological characters. The changes that occur from the innermost phloem out to the periphery of the stem are discussed and are compared with previous descriptions of cordaite phloem.