206 
IOWA ACADEMY OF SCIENCES. 
32. S. cristata Engelm. The type of this rare species 
was discovered in 1881, in a small lake, east of 
Armstrong. The station has since been destroyed 
but the plant occurs in several localities in 
Minnesota. 
VALLISNERIACE^. 
Philotria Raf. Ditch-moss. 
33. P. canadensis (Michx.) Britton. Rare in rivers and 
lakes. 
Vallisneria L. Eel-grass. 
34. A. spiralis L. Rather frequent in lakes, but rarely 
seen in flower. 
poace^:. 
Andropogon L. Beard-grass. 
35. A. scoparius. Michx. Common on rather dry 
prairies. 
36. A. furcatus Muhl. ( A provincialis Gray’s Man.) 
Crow-foot grass; very common; a valuable species 
for hay and pastures, but like most of our native 
grasses, quickly destroyed by close grazing. 
SoRGHASTR.UM Nasll. 
37. S. avenaceum (Michx.) Nash. ( Chrysopogon avena- 
ceus Michx.) Benth. ( Sorghum nutans Gray). 
Common on prairies with the preceding species. 
Syntherisma Walt. 
38. S. sanguinale (L.) Nash. ( Panicum sanguinale L.) 
A worthless European species introduced in cul- 
tivated and waste ground. 
33. S. linearis (Krock.) Nash. ( Panicum glabrum Gme- 
lin.) Common; banks of lakes and streams. 
Echinochloa Beauv. Barn-yard Grass. 
40. E. crus-galli (L.) Beauv. (. Panicum crus-galli L.) 
Introduced in cultivated and waste places. 
