10 ALISMACEAE 



1. ALISMA L. 



Flowers rather small, on three-bracteolate pedicels. Numerous ovaries 

 in a single whorl on a flat receptacle. Achenes flat, ribbed on the back 

 and sides. 



1. A. Plantago L. WATER PLANTAIN. Leaves ovate or ovate-lan- 

 ceolate, 3-10-nerved : panicle compound, many-flowered, 8 / -2 high. 

 Abundant in the pond north of Sheffield, at Lake City, Fish Lake and 

 Hiffner's Lake. June-September. 



2. ECHINODORUS Rich. 



Inflorescence usually somewhat branched, bearing the pedicelled 

 flowers in whorls of 3-6. Ovaries many, capitate, on a large convex 

 receptacle. Achenes ribbed and beaked, forming spinose heads. 



1. E. cordifolius (L. ) Griseb. BUR-HEAD. Leaves of two kinds, the 

 emersed thick, broadly ovate, cordate at base, the blade 6 / -8 / long, and 

 nearly as wide : the submersed leaves smaller, thin and often pellucid, 

 lance-ovate and rounded at base : scape erect, l-3 high. Often com- 

 mon in swamps and ditches in the Missouri River bottoms. June-Sep- 

 tember. 



Var. lanceolatus (Engelm.) Mackenzie & Bush, n. comb. A low 

 form not more than 6 / high with narrowly lanceolate leaves acute at 

 base, and a small panicle bearing few heads. Hiffner's Lake near Ather- 

 ton. July. (E. rostratus var. lanc.eolatus Engelm. ) 



3. LOPHOTOCARPUS T. Durand. 



Verticels few-flowered, the lower flowers perfect, the upper staminate. 

 Sepals inclosing fruit. Pistils numerous. Achenes winged. 



1. L. calycinus (Engelm.) J. G. Smith. FALSE ARROW-HEAD. 

 Scape 3 / -15 / high, shorter than the leaves, at length 'decumbent : 

 flowers borne on long pedicels, the fertile pedicels recurved : leaves 

 broadly sagittate or hastate, the lobes widely spreading. Uncommon on 

 wet sand-bars along the Missouri River, but abundant in the pond north 

 of Sheffield, and at Hiffner's Lake. July-October. 



4. SAGITTARIA L. ARROW-HEAD. 



Much like the last. Lower flowers pistillate, the upper staminate. 

 Sepals reflexed or spreading in fruit. Stamens usually numerous, cover- 

 ing the convex receptacle. Rootstocks bearing large tubers which often 

 completely cover the bottoms of swamps where these plants are numerous. 



Fruiting heads sessile. 2. 8. rigida. 

 Fruiting heads pedicelled. 



Leaf-blades sagittate. 1. S. latifolia. 



Leaf-blades lanceolate. 3. S. graminea. 



