. Fossil plants : for students of botany and geology . Paleobotany. XX] RECENT FERNS 313 may be described as the result of the replacement of some of the axial conducting tracheae by parenchyma or other non-vascular tissue consequent on an increase in diameter of the whole atele and the concentration of the true conducting elements towards the periphery^. The occurrence of the internal cylinder of phloem, pericycle, and endodermis in a solenostele is rendered intelligible by a study of fern seedlings and by a comparative examination of transitional types connecting protosteles and solenosteles
. Fossil plants : for students of botany and geology . Paleobotany. XX] RECENT FERNS 313 may be described as the result of the replacement of some of the axial conducting tracheae by parenchyma or other non-vascular tissue consequent on an increase in diameter of the whole atele and the concentration of the true conducting elements towards the periphery^. The occurrence of the internal cylinder of phloem, pericycle, and endodermis in a solenostele is rendered intelligible by a study of fern seedlings and by a comparative examination of transitional types connecting protosteles and solenosteles through medullated protosteles and steles of the Lindsaya type. A. Fio. 240. Cyathea Imrayana. (From Tansley after de Bary.) (Solerenohyma represented by black bands.) further stage in stelar evolution is illustrated by what is termed the dictyostele, the arrangement of vascular tissue characteristic of Nephrodium Filix-mas, Cyathea (fig. 240), Polypodium vulgare and many other common ferns. If a solenostele is interrupted by leaf-gaps at intervals sufficiently close to cause overlapping, a transverse section at any part of the stele will show apparently separate curved bands of concentrically arranged xylem and phloem, which on dissection are seen to represent parts of a continuous lattice- ^ For an account of the probable methods by which this has been effected and of the factors concerned, see Tansley (08).. 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
