. Heredity and evolution in plants. Heredity; Plants. 132 HEREDITY AND EVOLUTION IN PLANTS either as new formations, developed (by enation") on some primitive reproductive axis like a strobilus or cone, or else. Fig. 66.—Diagram to show the increase in prominence of the sporo- phyte stage of plant life from the algae to the higher seed-plants. Among the thallophytes both the sexual and asexual methods of reproduction are represented. A illustrates the asexual, wherein certain cells of the plant divide into smaller cells, the zoospores, which, without union with other cells, develop direct
. Heredity and evolution in plants. Heredity; Plants. 132 HEREDITY AND EVOLUTION IN PLANTS either as new formations, developed (by enation") on some primitive reproductive axis like a strobilus or cone, or else. Fig. 66.—Diagram to show the increase in prominence of the sporo- phyte stage of plant life from the algae to the higher seed-plants. Among the thallophytes both the sexual and asexual methods of reproduction are represented. A illustrates the asexual, wherein certain cells of the plant divide into smaller cells, the zoospores, which, without union with other cells, develop directly into new plants. B-E illustrate the sexual method, effected through an alternation of generations, wherein a vegetative stage, the sporophyte, alternates with a reproductive stage, thie gametopyte. (After Shimer.) as produced by the sterilization of parts originally fertile, , modifications of reproductive tissues. The sporophyte has become increasingly well developed and increasingly independent, while the gametophyte has become increas- ingly simple and increasingly dependent. The evolution of plants has proceeded by the progressive development of the sporophyte, and the gradual but steady regression of the gametophyte. This changing relationship is roughly indicated in the following diagram (Fig. 67, and also in Fig. 66). 107. Steps in the Evolution of the Sporophyte.—The. 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 Gager, C. Stuart (Charles Stuart), 1872-1943. Philadelphia, P. Blakiston's Son & Co.
Size: 2266px × 1103px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1920, booksubjectplants, bookyear1920
