. Embryogenesis in plants. Embryology. Fig. 79. Examples of apomixis A, Liliiim martagon. The proembryo on the left has arisen from a synergid and is hapioid; that on the right has developed from the zygote and is diploid (after Cooper). B-D, Semigamy in Rudbeckia speciosa. B, Two-celled proembryo with two small nuclei in basal cell. C, Three-celled proembryo show ing nuclei derived from sperm in terminal cell. D, More advanced stage; the nuclei derived from the sperm may occupy various positions (after Battaglia). E, F, Citrus trifoliata. Zygotic and nucellar embryos; in F, only the zygotic e
. Embryogenesis in plants. Embryology. Fig. 79. Examples of apomixis A, Liliiim martagon. The proembryo on the left has arisen from a synergid and is hapioid; that on the right has developed from the zygote and is diploid (after Cooper). B-D, Semigamy in Rudbeckia speciosa. B, Two-celled proembryo with two small nuclei in basal cell. C, Three-celled proembryo show ing nuclei derived from sperm in terminal cell. D, More advanced stage; the nuclei derived from the sperm may occupy various positions (after Battaglia). E, F, Citrus trifoliata. Zygotic and nucellar embryos; in F, only the zygotic embryo has a suspensor; the embryos are surrounded by endosperm (after Osawa). Maheshwari states that if the nucellus is intact, the adventive embryos will typically originate from some of its cells; but if the nucellus becomes disorganised, they may originate in the integument. (For other examples, see Maheshwari, 1950.) According to the species, adventive embryonic development may take place with or without the stimulus of pollination or fertilisation. The nature of those stimuli is of primary interest to the embryologist. In Eugenia jaiubos (Myrtales: Myrtaceae), adventive embryos originate without pollination, but only if the ovum is fertilised do they attain to their full development (Pijl,. 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
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