Sagittaria engelmanniana J.G.Sm.

Erect; lvs long-petioled, the blade sagittate (rarely merely lanceolate), its main portion mostly narrow, 4–10 × 0.2–2(–5) cm, (1–)2–many times as long as wide, with narrow, linear to lance-attenuate basal lobes; petioles rounded or with 2 blunt ridges on the abaxial side; scape 2–8 dm, with 2–4 whorls of fls, the upper staminate, the lower pistillate; pedicels 0.5–3.5 cm, ascending in fr; bracts herbaceous and relatively thick, 5–25 mm, mostly shorter than the pedicels; sep short, 4–7 mm, reflexed in fr; pet 8–12 mm; stamens 15–25, the slender, glabrous filaments as long as or longer than the anthers; mature receptacle markedly echinate; achenes 2.5–4 mm, with 1 or 2(3) wings on each face, these extending onto the obliquely ascending, 1–2 mm beak; achene-faces with resin-ducts; 2n=22. Acid waters of bogs, ponds, and streams near the coast from Mass. to Fla. and Miss., mainly on the coastal plain, but inland to w.c. N.Y. Aug., Sept.