. Fossil plants : for students of botany and geology . Paleobotany. 230 LYCOPODIALES [CH. secondary scalariform tracheae. The preservation of the tissues abutting on the edge of the wood is usually very imperfect, and the middle cortex of lacunar parenchyma has practically in every case eluded the action of mineralising agents; the outer cortex, on the other hand, consists of more resistant elements and is frequently well preserved. As in Lepidodendron and Sigillaria stems, meristematic activity produced a broad band of secondary cortex ; and beyond this were attached to cushion-like pads the
. Fossil plants : for students of botany and geology . Paleobotany. 230 LYCOPODIALES [CH. secondary scalariform tracheae. The preservation of the tissues abutting on the edge of the wood is usually very imperfect, and the middle cortex of lacunar parenchyma has practically in every case eluded the action of mineralising agents; the outer cortex, on the other hand, consists of more resistant elements and is frequently well preserved. As in Lepidodendron and Sigillaria stems, meristematic activity produced a broad band of secondary cortex ; and beyond this were attached to cushion-like pads the numerous appendages, each supplied with a single vascular bundle which arose from the primary xylem and passed out- wards through a medullary ray. There is abundant evidence that the appendages were hollow, a fact in striking accord with the aquatic and semi-aquatic habitat (cf Isoetes root, fig. 133, G).. Fig. 206. Cyperus papyrus. Piece of rhizome showing rootlet-sears. Nat. size. The piece of dried rhizome of Cyperus papyrus shown in fig. 206 is an almost exact counterpart of Stigmaria ficoides; the wrinkled and shrivelled surface and the circular root-scars containing the remains of a vascular bundle are striking features in common and, it may be added, the two plants, though very different in structure and in systematic position, illustrate anatomical adaptations to a similar 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
