Parr 1, 1909] ALISMACEAE 51 
with many distinct carpels. Receptacle more or less convex, spheroidal, or globose. 
Achenes numerous, flattened, densely crowded in globular heads, beaked. 
Type species, Sagittaria sagittifolia L. 
Sepals of the pistillate flowers ultimately lax or feflexed, not accrescent. 
Fruit-bearing pedicels reflexed or recurved. 
Stamens less than 10. 
Filaments glabrous. 
Scapes simple; phyllodia obtuse or abruptly pointed. 
Filaments about as long as the anthers; achenes with 3 undulate or slightly toothed 
1. Sy subulata. 
crests. 
Filaments much longer than the anthers; achenes with 
5-7 tuberculate or prominently toothed crests. 2. S. lorata, 
Scapes branched ; phyllodia slenderly attenuate. 3. S. filiformis. 
Filaments pubescent. 4. S. platyphylla. 
Stamens more than 10. 
Anthers subglobose; filaments longer than the anthers, much 
dilated. 5. S. demersa. 
Anthers oblong, filaments shorter than the anthers, slightly 
enlarged. 6. S. Sanfordit. 
Fruit-bearing pedicels ascending. 
Leaf-blades without basal lobes. 
Pedicels of the pistillate flowers as long as those of the staminate 
ones, or nearly so. 
Filaments dilated, relatively short. 
Leaf-blades terete or 3-sided, often imperfectly developed. 
Achenes with thin crested facial wings. 7. S. cristata. 
Achenes with thick merely uneven facial wings or 
ridges, 
Anthers longer than the filaments; achenes with 
several facial wings. 8. S. teres. 
Anthers shorter than the filaments; achenes with 3 
low facial ridges. 9. S. isoetiformis. 
Leaf-blades flat. 
Filaments suborbicular ; anthers much longer than the 
filaments. 10. S. Batoni. 
Filaments lanceolate, oblong, or ovate; anthers about as 
long as the filaments. 
Achenes oval or broadly oblong. 11. S. cycloptera, 
Achenes cuneate. 
Beak large, horizontal at the top of the achene- 
body. 12. S. Mohrii. 
Beak minute, borne much below the top of the 
achene-body. 
Inflorescence simple ; lower bracts ovate, united 
to the middle; achenes with lateral ribs or 
wings. 13. S. graminea. 
Inflorescence widely branched ; lower bracts 
lanceolate, united at the base; achenes with- 
out lateral ribs or wings. 14. S. Chapmanii. 
Filaments not dilated, slender. 
Filaments glabrous. 
Achene cuneate, the beak on the side above the middle 
of the body ; bracts broad, well united. 15. S. papillosa. 
Achene curved-oblong, the beak horizontal at the top of 
the body ; bracts narrow, distinct or nearly so. 
Filaments pubescent. 
Bracts and sepals granular-papillose. 
Bracts and sepals ribbed. 
Achenes more or less falcate, gradually beaked, the 
dorsal wing thick and even. 
Achenes not falcate, abruptly beaked, the dorsal 
wing usually thin and crested. 
Pedicels of the pistillate flowers very short or nearly wanting. 
Fruit-heads not echinate; achenes broadly winged and short- 
beaked; anthers broadly oblong, about as long as the 
filaments. 
Fruit-heads echinate; achenes narrowly winged and long- 
beaked ; anthers suborbicular, shorter than the filaments. 
Leaf-blades with basal lobes. 
Achenes with flat, ridged, or winged faces. 
Achenes minutely or inconspicuously beaked. 
Beak horizontal. 
Beak borne below the top of the achene-body. 
Beak borne at the top of the achene-body. 
Stamens 25 or fewer; achenes narrowly winged, 
without facial wings. ; 
Stamens 30 or more; achenes broadly winged, with 
facial wings. 
16. S. ambigua. 
17. 
S. falcata. 
18. S. lancifolia. 
19, S. angustifolia. 
20. S. macrocarpa. 
21. 
13 
nN 
LS) 
23 
S. rigida. 
. S. graminea, 
. S. longiloba, 
. S. Greggii. 
