Substantial evidence supports morpho-physiological dormancy (MPD) as the basal kind of seed dormancy in flowering plants. However, for seeds of waterlilies (Nymphaea, Nymphaeaceae), only physiological dormancy (PD) is reported.
Dalziell et al. determine seed dormancy and germination traits for six tropical Australian species of Nymphaea. Mature seeds of all species were dormant. Embryos in N. macrosperma, N. ondinea and N. violacea seeds lengthened prior to germination, and seeds of these species have MPD. Seeds of the other species possess PD. Results show seeds in the most phylogenetically derived clades within Nymphaea have MPD, suggesting PD is likely the basal trait within the Nymphaeales.
Dalziell, E. L., Baskin, C. C., Baskin, J. M., Young, R. E., Dixon, K. W., & Merritt, D. J. (2018). Morphophysiological dormancy in the basal angiosperm order Nymphaeales. Annals of Botany, 123(1), 95–106. https://doi.org/10.1093/aob/mcy142