Sixweeks dropseed, also called tufted annual dropseed and six- 

 weeks sporobolus, is one of the few annual species of Sporobolus and 

 it is the only common and abundant one of our western ranges. This 

 delicate grass grows in small, few-leaved tufts which often appear as 

 fine, bushy masses of panicles. The specific name microspermus, 

 meaning small seed (micrvs, small; sperma, seed), is aptly chosen 

 for this grass. The common phrase sixweeks is often applied, espe- 

 cially in the Southwest, to short-lived annual plants whose growth 

 period, from germination to dissemination and death, usually occupies 

 only about. 6 weeks or so. 



Sixweeks dropseed is widely distributed, occurring from Washing- 

 ton to Montana, western Texas, and California, and south into Mexico, 

 but is most common and abundant in the Southwest. It varies widely 

 in habitat but is very common along the edges of streams and in 

 moist places in the woodland and ponderosa pine belts, and some- 

 times at higher elevations. In the Southwest it occurs sporadically 

 on a wide variety of soils and sites, but is commonest on moist, sandy, 

 gravelly, or clayey loam soils in sheltered places and rocky cliffs at 

 elevations from 3,000 to 9,500 feet. 



The abundance of this annual, as is the case with most annuals, 

 depends largely upon climatic conditions and the extent of depletion 

 of the normal plant cover. It produces a very plentiful supply of 

 seed when conditions are favorable and, when summer rains are ade- 

 quate, it springs up abundantly in open sites and on bare ground. 

 At times it comes in thickly on open, overgrazed areas during favor- 

 able growing seasons. Sixweeks dropseed is often associated with 

 weeds and other annual grasses and also occurs sparsely with sedges 

 (Carex spp.}, gramas (Bouteloua spp.), hilarias (Hilaria spp.), and 

 other perennial grasses. 



Although sixweeks dropseed is worthy of mention here chiefly 

 because of its commonness and local abundance, its forage value is 

 slight or distinctly minor. The larger plants may be grazed to some 

 extent but, because of its very small size, sparse leafage, and bushy 

 panicles, it is ordinarily unattractive to grazing animals. If grazed 

 early in the season it may furnish a small amount of fair forage in 

 the absence of more palatable plants. 



This grass has a few narrow leaves from 1 to 2i/ inches long, and 

 several to many slender, often poorly developed stems 2 to 10 inches 

 high; occasionally, however, under favorable conditions, relatively 

 luxuriant growth, as much as 15 inches high, may occur. The 

 panicles are spreading, with many very fine branches, and are often 

 more than half the length of the entire plant. Frequently, the 

 upper two-thirds of the plant is a fine, loose mass of flowers or seeds. 



