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Secondary phloem anatomy in Callistophyton boyssetii (Renault) Rothwell and histological changes in the outer phloem
Smoot, Edith L.
Smoot, Edith L.
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Abstract
Specimens with well-preserved phloem tissues of the pteridosperm Callistophyton boyssetii from coal
balls in the Herrin no. 6 Coal of Illinois and the Bevier Coal of Kansas are described. The secondary phloem
consists of alternating tangential bands of sieve cells and parenchyma, separated by vascular rays. Secretory
cells are scattered throughout the secondary phloem, and bundles of presumed primary phloem are evenly
distributed in the cortex. Histological differences between the inner (presumably functional) and the outer
(presumably nonfunctional) phloem are described: changes in cell shape, thickening of cell walls, and deposition
of dark-colored cell contents. In contrast to living plants, both parenchyma cells and conducting
elements appear to undergo these changes. Phloem anatomy and developmental changes in the outer phloem
in Callistophyton are compared with those in other Carboniferous seed ferns and extant gymnosperms.
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This is the published version.
Date
1984-01-01
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University of Chicago Press
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Smoot, Edith L. "Secondary phloem anatomy in Callistophyton boyssetii (Renault) Rothwell and histological changes in the outer phloem." Botanical Gazette. Vol. 145 Issue, 3. pp. 395-406.