CYPERACEAE 19 



6. Scirpus. 174, 



Involucre of a single bract or wanting. 

 Spikelets few, 1 to 7, appearing lateral. 



Culms terete, bristles none, annuals. 1. S. hafliL 



Culms sharply triangular, bristles 2-4, perennials with rootstocks. 



2. S. americanus. 

 Spikelets numerous, umbellate. 

 Achene lenticular. 



Achene 2 mm. long nearly equalling the scale. 3. S. validus. 

 Achene 2.5-3 mm, long much exceeded by the scale. 



4. S. occidentalis. 

 Achene triangular, bristles unequal, shorter than achenes. 



5. S. heterochaetus. 

 Involucre of two or more leaves. 



Spikelets large, 1-5 cm. long, 5-10 mm. thick. 

 Achene lenticular, spikelets capitate. 6. S. Interior. 



Achenes sharply triangular, spikelets umbellate. 7. S. fluviatiTis. 

 Spikelets small, 2-15 mm. long. 1-3 thick. 



Scales dark brown, one third longer than achene. 



8. S. atrovirens. 

 Scales light brown, twice as long as the achene. 9. S. paHidus. 



1. Scirpus hallii Gray. 



Not common. Holt County; Kennedy, 



2. Scirpus americanus Pers, 



Common in the western parts of the state. Anselmo; Aten; Broken 

 Bow; Franklin; Hackberry Springs in Banner County; Hat Creek 

 Basin; Louisville; Red Cloud; Thedford. 



3. Scirpus vaiidus Vahl. Great bullrush. 

 Scirpus lacustris L, 



Common in marshes. Broken Bow; Cherry County; Lincoln; Nebras- 

 ka City; Newcastle; Scotts Bluff County; Thedford; Wahoo; Valen- 

 tine, 



4. Scirpus occidentalis (Wats.) Chase. 

 Kearney; Thedford. 



5. Scirpus heterochaetus Chase. 

 Nebraska, according to Britton's Manual, 



6. Scirpus interior Britton. 

 Scirpus campestris Britton. 



Alliance; Kearney County; in Lone Tree Lake near Kennedy; Laurel; 

 Lincoln; Newark; St, James; Whitman. 



7. Scirpus fluviatilis (Torr.) A. Gray. River buHrushr, 

 In wet, marshy places over most of the state. Kennedy; Merriman- 



8. Scirpus atrovirens Muhl. 



Common in wet places. Beatrice; Lincoln; Minden; Nehawka; St. 

 James; Weeping Water, 



9. Scirpus pallidus (Britton) Fernald. 

 Scirpus atrovirens var, pallidus Britton. 



Common in marshy places. Broken Bow; Crawford; Hitchcock Coun- 

 ty; Hooker County; Nebraska City; Talmage; Thedford; Wahoo. 



