9b. Nymphaea odorata subsp. tuberosa (Paine) Wiersema & Hellquist, Rhodora. 96: 170. 1994.
Nymphaea tuberosa Paine, Cat. Pl. Oneida Co., 132. 1865
Rhizomes often constricted at branch joints to form detachable tubers. Leaves: petiole green with brown-purple stripes, stout. Leaf blade abaxially green or faintly purple. Flowers: petals white, rarely pink, elliptic to oblanceolate, outer usually with broadly rounded apex. Seeds mostly 2.8-4.5 mm.
Flowering late spring-summer. Mainly alkaline ponds, lakes, and sluggish streams and rivers, usually in very oozy sediments; 100-400 m; Man., Ont., Que.; Conn., Ill., Ind., Iowa, Kans., Maine, Mass., Mich., Minn., Mo., Nebr., N.H., N.Y., Ohio, Okla., Pa., Vt., Wis.
This taxon, which has been included within Nymphaea odorata by some recent workers, was formerly almost universally accepted as a distinct species. In the southern parts of the range of subsp. tuberosa , where subsp. odorata is absent, subsp. tuberosa is easily distinguished morphologically from subsp. odorata . Farther north, where their ranges overlap, the distinctions break down in some populations but are maintained in others. Some western populations are probably the result of introductions. A pink-flowered form seen in southeastern Ohio appears to be derived from this subspecies.