. Studies in fossil botany . Paleobotany. 3i6 STUDIES IN FOSSIL BOTANY remembered, however, that in these Botryopterideae we are often dealing with specialised fertile fronds. Our illustration (Fig. 118) is taken from the petiole of another species, Z. bibractensis; Ren., in which the structure is rather more complex. The bundle has essentially the usual H-like sectional form, but hy ic x -^»' -yi N. Fn„ no.—Zygopteris ;isis. Transverse section of a petiole, showing the double- anchor form of stele, .r, middle band of xylem ; x'. the main lateral bands ; x", the small-celled e
. Studies in fossil botany . Paleobotany. 3i6 STUDIES IN FOSSIL BOTANY remembered, however, that in these Botryopterideae we are often dealing with specialised fertile fronds. Our illustration (Fig. 118) is taken from the petiole of another species, Z. bibractensis; Ren., in which the structure is rather more complex. The bundle has essentially the usual H-like sectional form, but hy ic x -^»' -yi N. Fn„ no.—Zygopteris ;isis. Transverse section of a petiole, showing the double- anchor form of stele, .r, middle band of xylem ; x'. the main lateral bands ; x", the small-celled external arcs of xylem ; the protoxylem lies between x' and x" ; , inner cortex ; hy. sderenchymatons hypoderma. X 7. From a photograph by Mr. L. A. Boodle. S. Coll. 014. the lateral pieces are considerably incurved, giving to the whole the shape of a double anchor. The peculiar feature of this species consists in the presence of an additional external band of xylem (x) on the outer side of each of the lateral plates (V), separated by parenchyma from the main lateral plate, but united with it at its two ends (Fig. I I 8). The external bands. 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 Scott, Dukinfield Henry, 1854-1934. London, A. and C. Black
Size: 1801px × 1387px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1900, bookpublisherlondonaandcblack
