. Heredity and evolution in plants. Heredity; Plants. 2l8 HEREDITY AND EVOLUTION IN PLANTS Angiospermous characters, and therefore, while they are not to be considered as the ancestors of the Angiosperms, it is probable that they and the modern dicotyledons are both descended from a common branch of the ancestral tree. Among modern plants, the flower of the magnolias most closely resembles that of Cycadeoidea in the spiral arrangement of its stamens and pistils (Figs. loi and 102). Just what significance should be attached to that fact has been disputed by students of morphology. The older vie
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. Heredity and evolution in plants. Heredity; Plants. 2l8 HEREDITY AND EVOLUTION IN PLANTS Angiospermous characters, and therefore, while they are not to be considered as the ancestors of the Angiosperms, it is probable that they and the modern dicotyledons are both descended from a common branch of the ancestral tree. Among modern plants, the flower of the magnolias most closely resembles that of Cycadeoidea in the spiral arrangement of its stamens and pistils (Figs. loi and 102). Just what significance should be attached to that fact has been disputed by students of morphology. The older view of the systematists rega, rded the primitive flower as more complex in structure, with pistils, stamens, and floral envelopes arranged spirally in centripetal or acropetal succession on a fleshy axis, as in Magnolia and other flowers of the order Ranales; other types of floral structure were con- FiG. io2.--Magnolia ^y^j.^^ ^^ derived from this one by Flower with perianth . , . ^ removed, showing the^ reduction. This IS often referred to compound pistil, and four as the "Strobiloid theory of the of the stamens. Most of flower" (C/. pp. 132 and 134). the stamens have been , , . removed so as to bring ^ more recent view recognizes out their spiral arrange- that simple staminate or pistillate ment as shown by the flowers may, in some cases, be in- !tt»rT, mpnt ^ ^f^ FiV terpreted as derived by reduction from more complex forms, but re- gards the primitive flower as uni-. attachment, lOI.) (C/. 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 work.. Gager, C. Stuart (Charles Stuart), 1872-1943. Philadelphia, P. Blakiston's Son & Co.