10 



CIRCULAR 804, U. S. DEPARTMENT OF AGRICULTURE 



when summer drought greatly reduces the production of late-growing 

 forage plants. Because herbage growth is normally slow in early 

 spring, the experimental ewes were forced to subsist largely on the 

 previous season's growth for the first few days of the grazing season. 

 They were observed to search for cured herbage but after the new 

 growth of Sandberg bluegrass and threadleaf sedge reached sufficient 

 height to be available, the old growth was seldom grazed. 



Table 2. — Stages of development of five important forage species on 

 northern Great Plains range l 



Species 



Spring growth 

 starts — 



In boot 2 



Spring growth 

 completed 



Sandberg bluegrass 



Threadleaf sedge 



Biuestem wheatgrass__ 



Blue grama 



Buffalograss 



Middle of March. __ 



Middle to late 



March. 

 Late March to 



early April. 

 Middle to late April _ 



Late April. 



Late April 



Early to mid- 

 April. 

 Early June 



Middle to late 



June. 

 June 



Mid- May to late 



June. 3 

 Late May. 



Late July. 



Do. 



Do. 











1 Dates given are average. 



2 Early stage of seed-head production. 



3 Varies widely, depending on spring rainfall. 



Biuestem wheatgrass, needle-and- thread, and certain other grasses 

 start growth soon after Sandberg bluegrass and threadleaf sedge. 



As the days lengthen and become warmer, blue grama, buffalo- 

 grass, and the summer forbs such as scarlet globemallow and prairie- 

 clover begin growth. The length of the growing period of these forbs 

 and the variety of such species which appear are closely related to 

 the amount and distribution of rainfall received. Blue grama and 

 buffalograss, like most of the perennial grass species, flower and com- 

 plete their growth by^ midsummer. Seed ripens and is disseminated 

 during late summer and early fall. 



The late summer and early fall periods are characterized by the 

 flowering of composite forbs such as hairy goldaster and prairie sun- 

 flower and most of the browse species. These plants produce seed 

 before the first frost but dispersal frequently occurs during the follow- 

 ing winter. 



Relative Grazing Values 



Preferences of the sheep for the many forage species varied with 

 weather, condition and abundance of forage, and many other factors. 

 In general, practically every species that occurred in the pastures was 

 utilized to some extent at some time during the grazing season. Even 

 pricklypear was grazed to a limited extent in early summer before the 

 spines on the new joints became rigid. Observations of grazing on the 

 species which provide the bulk of the forage are summarized in table 3. 

 The principal grasses and grasslike plants are very palatable and 

 provide forage from early spring until late fall. These species also 

 provide winter grazing unless unavailable because of snow. A few 

 other less abundant grasses supply some additional forage. The forbs, 



