Although the eudicots are just a subgroup of the flowering plants, they include more than half of all living plant species, outnumbering all other plant groups put together. This is especially notable since the eudicots have only been around since the middle of the Cretaceous, only about one-quarter of the history of land plants.
You can read about the morphological differences between monocots and dicots from our special exhibit.
For more information on current thought in angiosperm systematics, visit the Tree of Life.
S. B. Hoot, S. Magallón, & P. R. Crane, 1999. Phylogeny of basal eudicots based on three molecular data sets: atpB, rbcL, and 18S nuclear ribosomal DNA sequences. Ann. Missouri Bot. Gard. 86(1):1-32.