Nymphaea oxypetala stands out from the other evaluated species for having a greater number of differential characters, including angular collenchyma and the absence of bicollateral bundles in the petiole.
lingulata presents bicollateral bundles in the midrib (Figure 2F).
Bicollateral bundles (Figure 3D) occur in six species, except N.
oxypetala 2' Annular collenchyma, more than two layers of palisade parenchyma in mesophyll, more than two vascular bundles in middle vein of the blade, bicollateral bundle in petiole 3 Bicollateral bundle in blade, three vascular bundles in middle vein, six bicollateral vascular bundles in petiole N.
oxypetala, the six species have a bicollateral bundle, a characteristic cited by Sculthorpe (1967) for the petiole of this genus.
Among the fossil forms, Fascivarioxylon (Jain, 1962), of the Jurassic of India, has a vascular cylinder with mesarch, bicollateral
centrifugal-centripetal bundles, with uniform secondary growth in both directions; and Stem B, found in the Argentinian Cretaceous, has inverse bundles inside the first vascular cylinder.