6. Nuphar sagittifolia (Walter) Pursh, Fl. Amer. Sept. 2: 370. 1814.
Nymphaea sagittifolia Walter, Fl. Carol., 155. 1788; Nuphar lutea (Linnaeus) Smith subsp. sagittifolia (Walter) E. O. Beal
Rhizomes 2-2.5 cm diam. Leaves floating or submersed; petiole terete. Leaf blade abaxially and adaxially green, linear to lanceolate, 15-30(-50) × 5-10(-11.5) cm, 3-5 times as long as wide, sinus less than 1/3 length of midrib, lobes usually divergent and forming V-shaped angle; surfaces glabrous. Flowers 2-3 cm diam.; sepals 6, abaxially green to adaxially yellow toward base; petals oblong, thick; anthers 3-5 mm, barely or not at all longer than filaments. Fruit green, ovoid, 3-3.5 × 2-3 cm, smooth basally, strongly ribbed toward apex, slightly constricted below stigmatic disk; stigmatic disk green, 14-18 mm diam., nearly entire; stigmatic rays 10-14, linear, mostly terminating 1-2 mm from margin of disk. Seeds 4-5 mm.
Flowering mid spring-early fall. Freshwater streams, rivers, ponds, and lakes of coastal plain, extending to freshwater tidal areas; of conservation concern; 0-50 m; N.C., S.C., Va.
Nuphar sagittifolia is probably best treated as a subspecies. Plants intermediate between it and N . advena are treated under N . advena . The clinal variation pattern between the two taxa is apparently maintained via selection by vernalization (C. E. DePoe and E. O. Beal 1969; E. O. Beal and R. M. Southall 1977).
This taxon is the Cape Fear spatterdock of the aquarium trade.