POLYEMBRYONY IN QUERCUS ALBA. 



BY LE ROY H. HARVEY. 



Polyembryony is found well distributed through the Spermatophytes 

 though occurring more frequently in the Gymnosperms tlian in the Angio- 

 sperms. The additional embryo or embryos, which may be either sporo- 

 phytic or gametophytic in origin, may arise in a variety of ways. Ernst^ 

 in 1901 pointed out that the cells of the (1) nucellus^ (2) integuments, 

 (3) a second egg, (4) a synergid, (5) fragmentation of the normal em- 

 bryo, (6) the antipodals, (7) the endosperm, (8) or the suspensor may be 

 responsible for the phenomenon. 



The occurrence of polyembryony in the Angiosperms is summarized 

 in the following table which is compiled from Ernst^ and Coulter and 

 Chamberlain-. The distribution is shown according to the Alliances, in 

 which I have followed the scheme of Engler and Gilg. " 



OCCURRENCE OF POLYEMBRYONY IN ANGIOSPERMS. 



A — Archichlamydeae 



XI. Fagales Quercus alba. 



XIV. Santalales Balanopora elongata. 



Balanopora globosa. 



Helosis guayanensis. 



Loranthus europaeus (.''). 



Santalum album. 



XVIII. Ranales Aconitum Napellus. 



XIX. Rhoeadales Glaucium luteum. 



XXI. Rosales Mimosa Denhartii. 



Schrankia uncinata. 



XXIII. Gerinales Citrus aurantium. 



Euphorbia dulcis. 



XXIV. Sapindales Euonymus latifolius. 



Euonymus americanus. 

 Mangifera indica. 



XXVII. Parietales Clusia alba. 



XXVIII. Opuntiales Opuntia vulgaris. 



Opuntia tortispina. 



19tb Mich. Acad. Sci. Rept., 1917. 



