. Fossil plants : for students of botany and geology . Paleobotany. xxix] LYGINOPTERIDEAE 49 B show the gradual divergence of the two meristeles of a petiole as they approach the level where it divides into two equal branches, a characteristic feature of Sphenopteris Hoeninghausi and allied fronds. At a lower level than that represented in fig. 406 the vascular strand of the petiole would have the form of a W as figured by Williamson in one of his earlier memoirs^- The phloem with scattered secretory sacs and the adjacent tissue of the leaf- stalk are occasionally preserved in wonderful perfec
. Fossil plants : for students of botany and geology . Paleobotany. xxix] LYGINOPTERIDEAE 49 B show the gradual divergence of the two meristeles of a petiole as they approach the level where it divides into two equal branches, a characteristic feature of Sphenopteris Hoeninghausi and allied fronds. At a lower level than that represented in fig. 406 the vascular strand of the petiole would have the form of a W as figured by Williamson in one of his earlier memoirs^- The phloem with scattered secretory sacs and the adjacent tissue of the leaf- stalk are occasionally preserved in wonderful perfection^. No endodermis has been recognised. Sclerous nests are scattered in the ground-tissue as are also secretory sacs (figs. 404, E; 405, A). A small root r has penetrated the parenchyma of the rachis shown in fig. 405, Fig. 406. Lyginopteris oldhamia. Transverse section illustrating branching of petiole, x 5. (From a drawing suppUed by Prof. Oliver.) Sphenopteris Hoeninghausi Brongn.^, founded on material from English Coal Measures, was regarded by Williamson as the foliage of Lyginopteris chiefly on the ground of the occurrence of emer- gences on the axes (figs. 404, A, B) and laminae of the impressions like those on the petrified stems, and this comparison received support from the resemblance of the fragments of pinnules asso- ciated with Lyginopteris and its petioles in the calcareous nodules 1 Wiffiamson (74) PI. Li. fig. 1. 2 Scott (09) B. fig. 139, p. 375. " Brongniart (28) A. p. 199, PI. Ln. S. Ill For synonymy, see Kidston (11) p. 42. 4. 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
