. Embryogenesis in plants. Embryology. Fig. 42. Variable cotyledon number in embryos A-E, Cedriis libani. A, Ordinary embryo with no fusion of cotyledons. B, C, Earlier and later stages in fusion. D, A large cotyledon that appears to have arisen by fusion. E, Evidence of cotyledon abortion. ¥-G, Pinus banksiana. F, Fusion of two cotyledons. G, Transverse section of a group of cotyledons; s, shoot apex (x 16, after Buchholz). found in seeds with a volume range from 50-140 cu. mm. {see also Butts and Buchholz, 1940). Embryonic Selection. Buchholz has shown that for a period of about five weeks d
. Embryogenesis in plants. Embryology. Fig. 42. Variable cotyledon number in embryos A-E, Cedriis libani. A, Ordinary embryo with no fusion of cotyledons. B, C, Earlier and later stages in fusion. D, A large cotyledon that appears to have arisen by fusion. E, Evidence of cotyledon abortion. ¥-G, Pinus banksiana. F, Fusion of two cotyledons. G, Transverse section of a group of cotyledons; s, shoot apex (x 16, after Buchholz). found in seeds with a volume range from 50-140 cu. mm. {see also Butts and Buchholz, 1940). Embryonic Selection. Buchholz has shown that for a period of about five weeks during the early embryogeny little differentiation takes place, the several embryos within the ovule competing for survival. This has been described as the period of embryonic selection. Once predominance has been attained by one embryo, it grows rapidly and differentiates all its organs in 10-12 days; seed ripening is completed in a few weeks with little change in seed size. When the embryo eventu- ally attains to its full size. Fig. 37, it is surrounded by the enlarged female gametophyte which has grown so as virtually to fill the remainder of the seed cavity, the whole being enclosed within the hard stony layer which constitutes the testa or seed 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 Wardlaw, C. W. (Claude Wilson), 1901-. London, Methuen; New York, Wiley
Size: 1465px × 1705px
Photo credit: © Paul Fearn / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookcollectionbiodiversi, booksubjectembryology
