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Aquatic and Wetland Vascular Plants of the Northern Great Plains

51. Alismataceae, the Water Plantain Family

3. Sagittaria L. -- Arrowhead, duck potato

6. Sagittaria rigida Pursh

Rhizomatous perennial, emersed and erect to submersed and lax, 1-6 dm tall or to 9 dm long in deeper water. Emersed leaf blades linear to oblong when emergent in deep water or lanceolate to ovate when growing in shallow water or mud, seldom 1-few of the blades with short, narrow basal lobes, not truly sagittate, mostly 4-15 cm long, to 7 cm wide; petiole sometimes bent near the blade; leaves comprised entirely of lax, linear phyllodes when deeply submersed, plants generally nonflowering in this condition. Inflorescence solitary, simple, erect when emersed or lax in deep water, usually not exceeding the longest leaves, often bent near the lowest node, with 2-8 whorls of flowers; bracts ca. 5 mm long, obtuse, connate at the base. Flowers female below, male or some perfect above, the female sessile or nearly so, on pedicels to 3 mm long, the male on slender pedicels 1-3 cm long; sepals ovate, 4-7 mm long, reflexed in fruit; petals white, ca. 2X as long as the sepals; filaments longer than the anther, roughened with minute hairs. Fruiting heads subglobose to somewhat flattened, to 1.5 cm across, apparently sessile and appearing bristly due to the rather prominent achene beaks; achenes 2.5-4 mm long, narrowly winged; beak inserted laterally and recurved upward, 0.8-1.4 mm long. Jun--Sep. Mud or shallow water of marshes, ponds, lakes and streams; uncommon in n and e NE; (Que. to MN, s to VA, KY, TN, MO and NE).
GIF- Distribution Map

Map key

Previous Section -- Sagittaria latifolia Willd.
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