3. Sagittaria platyphylla (Engelm.) J. G. Sm. 



Leaves erect, overtopping the scape; leaf blades ovate to elliptic or lanceolate, 

 unlobed, to 18 cm. long and 8 cm. wide; scape simple, with as many as 8 whorls, 

 the 1 to 4 lower whorls pistillate and with their thickish pedicels to 25 mm. long 

 and soon recurving; bracts ovate, obtuse, scarious, strongly connate, to 8 mm. 

 long; stamens with dilated pubescent filaments that are mostly longer than the 

 anthers; fruiting heads to 15 mm. in diameter; achenes cuneate-obovate, to 2 mm. 

 long and 1.2 mm. wide, the dorsal keel rounded to the subtruncate summit, the 

 faces with 1 to 3 narrow ridges; beak subulate, 0.3 mm. or more long, obliquely 

 ascending. S. graminea var. platyphylla (Engelm.) J. G. Sm. 



In mud or shallow water of marshes, streams, sloughs, swamps and ponds in 

 e. Tex. and Okla. (Atoka, Murray, Pushmataha, Choctaw, Latimer and Mc-Cur- 

 tain COS.), Apr.-Oct.; Mo. w. to Kan., s. to Tex. and Ala.; adv. in the Pan. Canal 

 Zone. 



4. Sagittaria lancifolia L. Fig. 62. 



Leaves erect; leaf blades ovate to elliptic or narrowly lanceolate, unlobed, taper- 

 ing to both ends, firm, to 4 dm. long and 1 dm. wide; scapes simple or branching 

 at lower nodes, the main axis with as many as 10 whorls, the lower 1 to 4 whorls 

 pistillate with pedicels to 25 mm. long, the staminate pedicels to 35 mm. long; 

 bracts ovate, obtuse, strongly papillose, to 15 mm. long, connate; sepals more or 

 less papillose; stamens with slender arachnoid filaments that are longer than the 

 anthers; fruiting heads about 15 mm. in diameter; achenes cuneate-oblanceolate, 

 falcate, to 2.5 mm. long and 1 mm. wide, dorsally narrowly winged, usually with 

 1 or 2 low facial ridges; beak obliquely inserted, subulate from a thick base, to 

 0.8 mm. long, ascending. S. falcata Pursh. 



In fresh-water and brackish tidal marshes, swamps, and along streams in s.e. 

 Tex. and Okla., May-Nov.; Fla. to Tex., n. to Del.; also Mex. and C.A. 



Our plants, as described here, have been segregated as subsp. media (Mich.) 

 Bogin. 



5. Sagittaria papillosa Buch. Fig. 63. 



Leaves erect; leaf blades linear to narrowly lanceolate, to 25 cm. long and 5 cm. 

 wide; scapes typically branching from the lowest whorl, the main axis with as 

 many as 10 whorls, the lower 1 to 4 whorls pistillate with pedicels much shorter 

 that those of the staminate; bracts ovate, obtuse, somewhat connate, densely 

 papillose, to 1 cm. long; sepals to 6 mm. long, more or less papillose; petals about 

 twice as long as the sepals; stamens with linear glabrous filaments to 1.6 mm. long; 

 fruiting heads about 1 cm. in diameter; achenes cuneate, to 1.5 mm. long and 

 1 mm. wide, with the remotely crested dorsal wing about 0.2 mm. wide and the 

 ventral wing somewhat narrower, the faces plane; beak broad-based, laterally 

 inserted above the middle of the achene body, more or less recurving, about 0.2 

 mm, long. 



In swamps, marshes, bogs, ditches, small ponds and depressions in prairies in 

 e. and s. Tex. and e. Okla. (McCurtain Co.), Mar.-Nov.; Ark., La., Okla. and 

 Tex. 



6. Sagittaria ambigua J. G. Sm. 



Plant erect; leaves lanceolate to ovate, 12-20 cm. long, 4-10 cm. wide, the 

 petioles to 35 cm. long; scape erect, 3-9 dm. tall, with 2 to 10 whorls of flowers; 

 pistillate pedicels 15-35 mm. long, longer than the staminate pedicels; bracts 

 linear to lanceolate, acuminate, slightly papillose, mostly 1-3 cm. long, nearly 

 free; pedicels ascending, 1-2.5 cm. long; sepals oblong, 5-7 mm. long, remotely 

 papillose; petals ovate, 8-10 mm. long; filaments slender, glabrous; fruiting heads 

 1-1.5 cm. in diameter; achenes cuneate-obovate, 1.5-2 mm. long, 0.8-1.4 mm. 

 broad, narrowly thin-winged, the faces smooth or with a longitudinal thin keel; 



147 



