

ALISMACEAE 



Filaments much longer than the^anthers : achenes with 5-7 crenate 



or dentate crests. 

 Scapes branching. 

 Filaments pubescent. 



Pedicels of the pistillate flowers slender, ascending, or wanting. 

 Leaf-blades entire or barely hastate, sometimes greatly reduced. 

 Pistillate flowers pedicelled. 

 Filaments dilated. 



Pedicels of the pistillate flowers shorter than those of the stam- 



inate. 

 Pedicels of the pistillate flowers as long as those of the staminate 



or longer. 

 Leaves terete, mostly bladeless. 



Filaments as long as the anthers : achenes 1 mm. long, with 



low facial ridges. 

 Filaments shorter than the anthers : achenes 2 mm. long, 



with several facial wings. 

 Leaves with more or less flattened blades. 

 Achenes oval or broadly oblong. 

 Achenes cuneate. 



Beak large, horizontal at the top of the achene. 

 Beak minute, much below the top of the achene. 

 Bracts ovate, united to the middle. 

 Bracts lanceolate, nearly distinct. 

 Filaments slender, not dilated. 

 Filaments glabrous. 



Bracts ovate, obtuse, united to about the middle : beak near 



the middle of one side of the achene. 



Bracts lanceolate, acuminate, distinct or nearly so : beak hori- 

 zontal at top of the achene. 

 Filaments pubescent. 

 Pistillate flowers sessile. 

 Leaf-blades mostly sagittate. 



Basal lobes twice or thrice as long as the middle lobe. 

 Basal lobes shorter than the middle lobe. 



Pedicels of the pistillate flowers much shorter than their bracts. 

 Pedicels of the pistillate flowers surpassing their bracts. 

 Filaments villous, not dilated : bracts and sepals viscid. 

 Filaments glabrous : bracts and sepals not viscid. 



Beak of the achene erect, the tip sometimes recurved. 



Lobes of the leaf-blades ovate, obtuse : achenes broadest at 



the top with 1 facial wing on each side. 

 Lobes of the leaf-blades linear or nearly so, acute : achene 

 broadest at the middle with 2 facial wings on each side. 

 Beak of the achene lateral, horizontal or oblique. 



Foliage, especially that of the inflorescence, glabious. 

 Foliage, especially that of the inflorescence, pubescent. 

 Sepals of the pistillate flowers erect, accrescent. 



43 



2. S. watarts. 



3. S. filiformis. 



4. S.platyphytla. 



5. S. macrocarpa. 



6. S. isoetiformis. 



7. S. teres. 



8. S. cydoptera. 



9. S. Mohrii. 



10. S. graminea. 



11. S. Chapmanii. 



I 



12. S.'papittosa. 



13. S. ambifjita. 



14. S. lantifolia. 



15. S. rigida. 



16. S. longiloba. 



17. S. longirostra. 



18. S. viscosa. 



19. S. australis. 



20. S. Engelmanniana. 



21. S. latifolia. 



22. S. pubescens. 



23. S. Montevidensis. 



1. Sagittaria subulata (L. ) Buch. Monoecious or sometimes wholly staminate. 

 Leaves usually represented by rigid phyllodes 2-12 cm. long, rarely normal ; blades linear 

 to linear-lanceolate, 2-3 cm. long, acutish, shorter than the petioles : scapes 5-15 cm. tall, 

 rarely surpassing the leaves : whorls of the raceme solitary or often 2 : bracts thin, 1-3 

 mm. long : pedicels of pistillate heads 10-15 mm. long : sepals ovate-lanceolate, obtuse : 

 corollas 15 mm. broad : achenes few, 1.5 to nearly 2 mm. long, with short lateral beaks 

 and 3 prominent but merely undulate or sparingly toothed crests. 



In mud and tidal flats, New York to Florida and Alabama. Summer and fall. 



2. Sagittaria natans Michx. Monoecious, commonly submerged. Petioles blade- 

 less, or blades floating, elliptic, oblong or ovate-oblong, 1.5-5 cm. long, rounded, subcor- 

 date or hastate-truncate at the base : phyllodes flattened, elongated : scape elongating to 

 the surface of the water or rising above it, 1-10 dm. long : whorls of the inflorescence one 

 or several : bracts thin, acuminate : mature fruiting heads 8 mm. in diameter : achenes 

 rather numerous, 2 mm. long, with short upcurved beaks and 5-7 prominently dentate or 

 crenate crests. 



In fresh or brackish ponds, South Carolina to Florida. Summer and fall. 



3. Sagittaria filiformis J. G. Smith. Monoecious, submerged. Leaves wanting : 

 phyllodes filiform from thicker bases, 1-6 dm. long, rarely as long as the scape : scapes 

 slender, 6-12 dm. long, often branching from the lower whorls : bracts lanceolate, 3-5 mm. 

 long, acuminate : pedicels filiform, those of the lower whorls 1-4 cm. long, ascending or 

 erect : whorls remote, staminate except 1 or 2 flowers of the lower one : sepals ovate, 2-3 

 mm. long, obtuse : corolla white, about 2 cm. broad : mature fruiting heads 6-7 mm. in 

 diameter : achenes 1.5 mm. long, with upcurved lateral beaks and about 6 crests. 



In ponds, Florida and Alabama. Spring and summer. 



4. Sagittaria platyphylla (Engelm. ) J. G. Smith. Monoecious. Leaf-blades rather 

 leathery, lanceolate, elliptic to ovate, 5-15 crn. long, 5-7-nerved, acute or acuminate, 

 gradually narrowed or subcordate at the base : scapes 2-5 dm. tall, usually overtopped by 



