FIGURE 4. Evolution of female gametophyte structure and ploidy level of endosperm in basal angiosperms.

Phylogeny based on recent published analyses (see text). Clades for which plesiomorphic character states are known are indicated with a colour-coded box under the taxon name. Endosperm ploidy is known for Nuphar, many monocots and eudicots, and is inferred (on the basis of female gametophyte structure) for Amborella, Nymphaea, Cabomba, Schisandra, Illicium and eumagnoliids. The plesiomorphic condition for angiosperms is unresolved and could be either diploid or triploid. Under the constraints of this phylogenetic hypothesis, either triploid endosperm evolved twice from a diploid condition during the early evolution of angiosperms (a) or diploid endosperm evolved twice from a triploid condition (b).