Glossary of "Plant Biology (1st ed.)" by Graham et al. (2003)
- A unique characteristic of flowering plants in which two sperm nuclei fuse with separate nuclei to produce a diploid zygote and a triploid endosperm.
Glossary of "Life (9th ed.)" by Sadava et al. (2011)
- In angiosperms, a process in which the nuclei of two sperm fertilize one egg. One sperm’s nucleus combines with the egg nucleus to produce a zygote, while the other combines with the same egg’s two polar nuclei to produce the first cell of the triploid endosperm (the tissue that will nourish the growing plant embryo).
- Graham, L. E., Graham, J. M. & Wilcox, L. W. 2003. Plant Biology. -xxxv + 497 pp. Pearson Education, Inc., Upper Saddle River.
- Sadava, D., Hillis, D. M., Heller, H. C. & Berenbaum, M. R. 2011. Life: The Science of Biology, 9th ed. -xliv + 1266 pp. Sinauer Associates, Inc., Sunderland.