Ueli Grossniklaus has a nice article in a recent issue of Science (Volume 323, page 1439)
"The male gametophyte (pollen) harbors two sperm cells, which are delivered to the female gametophyte (embryo sac) that is embedded in the ovule, the precursor of the seed. In flowering plants (such as Arabidopsis), one sperm fuses with the egg cell to form the zygote, whereas the second fuses with the central cell and develops into the endosperm, a nutritive tissue supporting the growth of the embryo".
I read this article at lunch today, while enjoying a colbyjack & lean ham whole wheat pita, a glass of 2005 Medoc ($6 from Trader Joes) and 3 different female hummingbirds buzzed the feeder a few feet away. Like most females universally, they found their normal food sources (red sugar water, aloe, and Spanish lavender) more nutritious than other alternatives.
1 year ago