290 



EMBRYOGENESIS IN PLANTS 



In addition to the zygotic embryos, otlier embryos may not infre- 

 quently be formed from the synergids (with or without the intervention 

 of a male nucleus), or from the antipodals — a more rare phenomenon. 



Fig. 80. Examples of polyembryony 



A, B, Ulmiis americana. Normal and antipodal embryos (after Shattuck). C, Ery- 

 throitium aniericanum. Proliferation of embryonic mass with formation of several 

 embryos (after Jeffrey). D, E, Eiilophea epidendraea. D, The zygote has formed 

 a group of cells, three of which have given rise to independent embryos. E, 

 A bud has been formed on the right-hand side of the embryo (after Swamy). F, 

 Elatostema simiatum eusinuatum. A zygotic embryo and three antipodal embryos 

 (one undergoing its first division). G, Elatostema eurhynchum. Zygotic and lateral 

 embryos. H, Elatostema acuminatum. Compound embryo-sac formed by the 

 fusion of two embryo-sacs; that on the right has two well developed embryos; ihat 

 on the left has two small embryos (F-H, after Fagerlind). 



Tn Ulmus americana (Urticales; Ulmaceae), the antipodal nuclei have 

 often an egg-like appearance and embryos are sometimes formed in 

 their vicinity (Shattuck, 1905), Fig. 80a, b. Antipodal embryos have 

 also been found in Ulmus glabra (Ekdahl, 1941), Allium odorum 

 (Liliaceae) (Modilewski, 1931), Sedum fabaria (Saxifragales : Cras- 

 sulaceae) (Mauritzon, 1933), and Elatostema sinuatum eusinuatum 



