. Studies in fossil botany . Paleobotany. BOTRYOPTERIS 329 adaxial protoxylem-groups commonly united into one, and as fusion with the stele took place, this group necessarily took up an internal position in the stelar wood ; every stage of the fusion is shown in serial sections of B. hirsuta or ramosa. Thus the xylem of the stele was endarch ; spiral elements are not often to be found in the stem, which was a comparatively. Fig. 122.—Botryopteris kirsuta. Transverse section of vascular bundle of young petiole, showing the xylem in course of differentiation, px, lignified protoxylem; x, thin-wa
. Studies in fossil botany . Paleobotany. BOTRYOPTERIS 329 adaxial protoxylem-groups commonly united into one, and as fusion with the stele took place, this group necessarily took up an internal position in the stelar wood ; every stage of the fusion is shown in serial sections of B. hirsuta or ramosa. Thus the xylem of the stele was endarch ; spiral elements are not often to be found in the stem, which was a comparatively. Fig. 122.—Botryopteris kirsuta. Transverse section of vascular bundle of young petiole, showing the xylem in course of differentiation, px, lignified protoxylem; x, thin-walled xylem not yet lignified; ph, phloem-zone. The dark external layer may be the endodermis. X 150. S. Coll. 564. R. S. short and presumably rather slow-growing rhizome. The small tracheides sometimes found at the periphery of the wood were probably in connection with the adventitious roots. The rachis of the English species often shows branching, its branches being given off singly, and not in pairs as in Zygopteris, but such knowledge as we have of the form and structure of the lamina is entirely. 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
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