. Fossil plants : for students of botany and geology . Paleobotany. 188 CYCADOXYLEAE [CH. by stems, our knowledge of the leaves being confined to the leaf- .traces in the stem which appears to have a phyllotaxis of f. The stem of tfiis Permian species has a diameter of 5—6 cm.: the comparatively broad cortex contains numerous secretory canals, but in place of hypodermal strands of stereome there is a super- ficial periderm. The vascular tissue, consisting of secondary. Fig. 453. A. Ptychoxylon Levyi; transverse section of stem; a, stele of branch. (After Renault.) B. Cycadoxylon Fremyi; transv
. Fossil plants : for students of botany and geology . Paleobotany. 188 CYCADOXYLEAE [CH. by stems, our knowledge of the leaves being confined to the leaf- .traces in the stem which appears to have a phyllotaxis of f. The stem of tfiis Permian species has a diameter of 5—6 cm.: the comparatively broad cortex contains numerous secretory canals, but in place of hypodermal strands of stereome there is a super- ficial periderm. The vascular tissue, consisting of secondary. Fig. 453. A. Ptychoxylon Levyi; transverse section of stem; a, stele of branch. (After Renault.) B. Cycadoxylon Fremyi; transverse section of stem. (After Renault.) C. Cycadoxylon robustum; centre of stem. 1—4, diagrams of sections of the stem of Ptychoxylon at different levels. (Simphfied from Renault) xylem and phloem, assumes different patterns at diSerent levels. There is an outer vascular cyUnder of centrifugally developed xylem and phloem; the xylem is manoxylic and the tracheids. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Seward, A. C. (Albert Charles), 1863-1941. Cambridge : University Press
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Keywords: ., bookcentury1800, bookdecade1890, bookpublishercambr, bookyear1898
