. Fossil plants : for students of botany and geology . Paleobotany. 328 FILICALES [CH. the xylem and separated from it by a parenchymatous sheath is a ring of phloem, ph, composed of large sieve-tubes and parenchyma separated from the inner cortex by a pericycle 4 to 5 layers in breadth. The occurrence of a few sclerotic cells beyond the broad inner cortex points to the former existence of a thick-walled outer cortex. The leaf-traces are ph. Fig. 249. Zalesskya diploxylon. Kidston and Gwynne-Vaughan. Transverse section of stem, ph, phloem. (After Kidston and Gwynne-Vaughan. x24.) given off as
. Fossil plants : for students of botany and geology . Paleobotany. 328 FILICALES [CH. the xylem and separated from it by a parenchymatous sheath is a ring of phloem, ph, composed of large sieve-tubes and parenchyma separated from the inner cortex by a pericycle 4 to 5 layers in breadth. The occurrence of a few sclerotic cells beyond the broad inner cortex points to the former existence of a thick-walled outer cortex. The leaf-traces are ph. Fig. 249. Zalesskya diploxylon. Kidston and Gwynne-Vaughan. Transverse section of stem, ph, phloem. (After Kidston and Gwynne-Vaughan. x24.) given off as mesarch strands from the edge of the xylem; they begin as prominences opposite the protoxylem and become gradually detached as xylem bundles, at first oblong in trans- verse section, then assuming a slightly crescentic and reniform shape, while the mesarch protoxylem strand takes up an endarch position. As a trace passes further out the curvature. 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
Size: 1631px × 1531px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1890, bookpublishercambr, bookyear1898
