4 genera in the Texas flora, each with 6 species. This combines, however, with specialization for a specific habitat - an aquatic environment. All species are aquatic, perennial herbs with underwater rhizomes and long-petioled, peltate leaves. The Nymphaeales is one of the few angiosperm Orders with all taxa adapted to a specific habitat. Also, all taxa of lack vessel elements.
Monocots also tend to lack vessel elements in the xylem.
Thus, of all dicot Orders and Families considered here, this one carries a possible link to the monocots.