[Castalia lekophylla Small, moreCastalia minor (Sims) Nyar., Castalia odorata Greene, Nymphaea minor (Sims) DC., Nymphaea odorata var. gigantea Tricker, Nymphaea odorata var. godfreyi Ward, Nymphaea odorata var. minor Sims, Nymphaea odorata var. rosea Pursh, Nymphaea odorata var. stenopetala Fernald, Nymphaea odorata var. villosa Casp.]
Rhizomes not constricted at branch joints, or only rarely so. Leaves: petiole uniformly greenish or more commonly reddish purple, rarely faintly striped, slender to stout. Leaf blade abaxially usually deeply reddish or purplish, occasionally greenish. Flowers: petals white, rarely pink, mostly lanceolate to elliptic, outer usually slightly or strongly tapering to apex, apex acute to rounded. Seeds 1.5-2.5 mm. 2 n = 56, 84. Flowering spring-early fall, mainly summer farther north. Acidic or alkaline ponds, lakes, sluggish streams and rivers, pools in marshes, ditches, canals, or sloughs; 0-1700 m; B.C., Man., N.B., Nfld., N.S., Ont., P.E.I., Que., Sask.; Ala., Ariz., Ark., Calif., Colo., Conn., Del., D.C., Fla., Ga., Idaho, Ill., Kans., Ky., La., Maine, Md., Mass., Mich., Minn., Miss., Mo., Mont., Nebr., Nev., N.H., N.J., N.Mex., N.Y., N.C., Okla., Oreg., Pa., R.I., S.C., Tenn., Tex., Utah, Vt., Va., Wash., W.Va., Wis.; Mexico; West Indies (Bahamas, Cuba); Central America (Honduras, El Salvador, Nicaragua); South America (n Guyana, naturalized). Nymphaea odorata subsp. odorata is introduced in British Columbia and in Arizona, California, Colorado, Idaho, Montana, Nevada, New Mexico, Oregon, Utah, and Washington. Intermediates to subsp. tuberosa (see previous comment for distribution) cannot be keyed satisfactorily to either subspecies. Plants of west-central Manitoba and east-central Saskatchewan, which are intermediate with Nymphaea leibergii in most floral characters, are only tentatively placed here. Unusually dwarfed plants that have been treated as Nymphaea odorata var. minor may be responses to highly acidic conditions. Very robust forms recognized by some as N . odorata var. gigantea occur sporadically along the coastal plain from New Jersey southward, perhaps in response to some unknown environmental factor. Further study should be undertaken. Occasional pink-flowered forms, treated as N . odorata var. rosea or forma rubra , are known from several states; all existing populations appear to be introductions for ornamental purposes. Natural hybrids with N . leibergii and N . mexicana are discussed under those species. Nymphaea reniformis Walter, an earlier name of uncertain application that has at times been applied to this taxon, has been recently proposed for rejection (J. H. Wiersema and J. L. Reveal 1991). Flowering responses in the northern part of the range, where the flowers generally open slightly later in the morning and close much later in the afternoon, are much more variable than those farther south.