. Bulletin of the British Museum (Natural History), Geology. . B Fig. 2. Two Recent petiole bases, a. Osmunda zeylanica. b. Todea barbara. In both the stipe (st) flanked by the wing stipules (w) but in Todea these stipules are fused across the adaxial side of the stipe producing a curved commissure line c. The thick diver- gent lines and in Todea vertical ones below the commissure, indicate sclerenchyma within. Clearly a transverse section at the level I in the two cases would appear quite different for in Todea the stipules would lie in front of and quite separate from the stipe, whereas in O
. Bulletin of the British Museum (Natural History), Geology. . B Fig. 2. Two Recent petiole bases, a. Osmunda zeylanica. b. Todea barbara. In both the stipe (st) flanked by the wing stipules (w) but in Todea these stipules are fused across the adaxial side of the stipe producing a curved commissure line c. The thick diver- gent lines and in Todea vertical ones below the commissure, indicate sclerenchyma within. Clearly a transverse section at the level I in the two cases would appear quite different for in Todea the stipules would lie in front of and quite separate from the stipe, whereas in Osmunda they would flank it on both sides. This would be apparent in the section of a fossil stipe at the appropriate level. Between the xylem strands it constitutes the " medullary rays " of some writers on Osmundaceae. It is encircled externally by phloem which is followed by tangen- tially elongate cells. The large horse-shoes of the incipient leaf traces cause a bulge in the surrounding parenchyma and phloem. When the leaf traces first appear they are surrounded by a branch of phloem and tangentially elongate cells (much obscured by fungi). ^ (PI. 12, fig. 24) shows very clearly the emergence of a root from one angle of an incipient leaf trace not yet separated from the xylem ring. Tracheids of the trace can be seen passing directly into the root. Further evidence as to root develop- ment is shown in PI. 8, fig. 16 ; PL 9, fig. 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 British Museum (Natural History). London : BM(NH)
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