go ALISMACEAE. 
7. Sagittaria ambigua J. G. Smith. 
Kansas Sagittaria. (Fig. 199.) 
Sagitlaria ambigua J. G. Smith, Ann. Rep. Mo. Bot. 
Gard. 6: 48. pl. 77. 1894. 
Mouoecious, glabrous, scape erect or ascending, 
simple or sparingly branched, 1°-2° high. Leaves 
lanceolate, entire, long-petioled, acute or acumin- 
ate at both ends, seemingly pinnately veined, really 
5-7-nerved, 5’-8’ long, equalling or shorter than 
the scape; bracts lanceolate, acuminate, 5/’/-8// 
long, much shorter than the slender fruiting pedi- 
cels, connate at the base, papillose; stamens 20- 
25; filaments glabrous, longer than the anthers; 
achene about 1’ long, oblong, curved, narrowly 
winged on both margins, its sides smooth and even, 
its beak short, oblique. 
In ponds, Kansas and the Indian Territory. 
8. Sagittaria lancifélia L. Lance-leaved Sagittaria. (Fig. 200.) 
Sagitiaria lancifolia 1,. Amoen. Acad. 5: 409. 1760. 
Sagittaria falcata Pursh, Fl. Am. Sept. 397. 1814. 
Sagitlaria lanctifolia falcata J. G. Smith, Mem. Torr. 
Club, 5:25. 1894. 
Monoecious, glabrous, scape rigid, erect, stout 
or rather slender, striate, branched or simple, 
longer than the leaves. Leaves lanceolate or ob- 
long-lanceolate, acute or acuminate at both ends, 
firm, entire, the blades 5-9-nerved, 8/-114° long, 
gradually narrowed into the long petioles, appar- 
ently pinnately veined; flowers numerous, 5/’~12// 
broad; bracts ovate or ovate-lanceolate, usually not 
united at the base, glabrous or nearly so, equalling 
or shorter than the fruiting pedicels; stamens 
numerous ; filaments cobwebby-pubescent, equal- 
ling or longer than the anthers; achene narrowly 
obovate-cuneate, 1’//-114’’ long, winged on both 
margins, its sides smooth, its beak tapering, oblique. 
In swamps and shallow water, Delaware, to Florida 
and Texas, near the coast. Widely distributed in trop- 
ical America. 
g. Sagittaria rigida Pursh. Sessile-fruiting Arrow-head. (Fig. 201.) 
Sagittaria rigida Pursh, Fl. Am. Sept. 397. 1814. 
Sagittaria heterophylla Pursh, Fl. Am. Sept. 396. 1814. Not 
Schreb. 1811. 
Monoecious, glabrous, scape simple, weak, curving, 
ascending or decumbent, shorter than the leaves. Leaves 
very variable, linear, lanceolate, elliptic or broadly ovate, 
acute or obtuse at the apex, entire or with I or 2 short or 
slender basal lobes; bracts ovate, obtuse, 2’’-4’’ long, 
united at the base or sometimes distinct; heads of fruit 
sessile or very nearly so; pedicels of the sterile flowers 
44/-1’ long; filaments dilated, mostly longer than the 
anthers, pubescent ; achene narrowly obovate, 113//-2// 
long, winged on both margins, crested above, tipped with 
a stout nearly erect beak of about one-fourth its length. 
-_Inswampsand shallow water, Quebec to Minnesota, south to 
New Jersey, Tennessee, Missouri and Nebraska. Petioles 
rigid when growing in running water. July—Sept. 
