Hydatellaceae is a group of water plants that are now discovered to be part of the initial emergence of flowering plants back in the Mesozoic Era. The plant shows a number of rare embryological features which, in combination, are found only in members of the equally primitive Nymphaeales (water lilies). But Hydatella has one additional feature, the provisioning of the seed from maternal rather than embryonic tissue, which is unique among flowering plants, but relatively common among gymnosperms.
