. Heredity and evolution in plants . FIG. 86.—Lyginodcndron oldliamium. Pinna of a microsporophyll,found in an ironstone nodule. Before its identity \vas established thisspecimen was named Cntssollicia llocninghansi. The somewhat peltatefertile pinules on the ultimate branches, bear each a fringe of micro-sporangia about 3 mm. long. The appearance has been likened to thatof a fringed epaulet. (After Scott, from a photo by Kidston.) ter, and provided with spines by means of which it prob-ably climbed on its neighbors. The foliage was disposedspirally and consisted of relatively very large, fine
. Heredity and evolution in plants . FIG. 86.—Lyginodcndron oldliamium. Pinna of a microsporophyll,found in an ironstone nodule. Before its identity \vas established thisspecimen was named Cntssollicia llocninghansi. The somewhat peltatefertile pinules on the ultimate branches, bear each a fringe of micro-sporangia about 3 mm. long. The appearance has been likened to thatof a fringed epaulet. (After Scott, from a photo by Kidston.) ter, and provided with spines by means of which it prob-ably climbed on its neighbors. The foliage was disposedspirally and consisted of relatively very large, finelydivided fronds with small, thick pinnules with revolute THE EVOLUTION OF PLANTS 203 margins, suggesting a xerophytic or halophytic stem in the lower portion gave rise to numbers ofslender roots, some of which appear to have been aerialin their origin. These grew downward and often branchedwhere they entered the FIG. 87.—Young leaf of the Cycad, Bowenia scrrulata. Comparisonof this with a leaf of the fern Angioptcris (Fig. 88) shows how difficultit might be to decide from a fossil leaf whether the plant was a cycad or afern. (Cf., also, Fig. 91.) (Photo from specimen in Brooklyn BotanicGarden.) The stems, roots, and petioles, and even the pinnules,have been found calcined and so beautifully preservedthat their entire structure can be made out with going into a technical description of these organs,it may be said that the stem when young, and beforesecondary growth has begun, has a very strong resemblance 204 HEREDITY AND EVOLUTION IN PLANTS to the stem of [the fern] Osmunda, but when more mature certain cycadean characters appear to Its foliage and other characters closely resemble some of our modern tree-ferns (Cf. Figs. 87 and 88), but more
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Keywords: ., bookcentury1900, bookdecade1920, bookidheredityevol, bookyear1920
