Plants are sexual creatures, just like animals, and just like animals, they produce haploid gametes - the sperm and the egg - that unite to form the next generation.
However, the haploid form of plants is more than just the naked gametes. Unlike in animals, there is a multicelluar haploid structure, termed the gametophyte, that forms and houses the actual gamete. In higher plants, the gametophyte is a small (though important!) structure containing only a few cells, all of them haploid. The male gametophyte is called the pollen, and the female gametophyte is called the embryo sac. Both male and female gametophytes develop inside of the flowers of adult plants, totally surrounded by sporophytic tissue. This can make it difficult to study their development, particularly for the female gametophyte which cannot be isolated and is difficult to observe directly.
During my graduate work in the lab of Sebastian Bednarek at the University of Wisconsin, Madison, I characterized an Arabidopsis thalliana mutant named drp2AaBb that failed during both male and female gametophyte development (Backues et al. (2010) Plant Cell 22:3218-3231). While characterizing this mutant, I also looked at wild type gametophyte development in Arabidopsis by light and electron microscopy. From those images I have put together overviews of both male gametophyte development and female gametophyte development in Arabidopsis, complete with descriptions, references, and lots of pictures. So, if you are interested in learning more about plant gametophyte development, or just looking at some cool pictures, follow the links below.