Figure 1 6 . — Four-year-old 

 transplants of black 

 sagebrush (A. nova J j 

 lefts <2"<i basin big 

 sagebrush (k. tridentata 

 ssp. tridentatajj right. 

 Specimens growing at an 

 ada:ptation plot near 

 Ephraim, Sanpete Co., Utah. 



The principal difference between black sagebrush and low sagebrush is that low 

 sagebrush has 5 to 11 flowers per head, 10 to 15 canescent involucral bracts, and is 

 light in color. Black sagebrush has fewer flowers per head (3 to 5) , 8 to 12 glabrous 

 involucral bracts, and is usually darker in color. Also, the flower stalks of black 

 sagebrush are denser, much darker, and more persistent than those of low sagebrush 

 (Ward 1953) . 



Black sagebrush flowers from August to mid -September, and seeds mature in October 

 and November. Cleaned seed averages 2,000 per gram (907,000 per pound) (Plummer and 

 others 1968) . 



Insect galls are numerous on this species, but rust diseases are less common 

 (Beetle 1960) . 



Hybridization . --Both diploid (2n = 18) and tetraploid (2n = 36) forms of black 

 sagebrush have been found (Ward 1953; McArthur and Plummer 1978) . Beetle (1960) has 

 found evidence of A. nova hybridizing with A. bigelovii, A. tridentata ssp. tridentata, 

 and A. tridentata ssp. vaseyana. Crossing between black sagebrush and basin big sage- 

 brush is fairly common wherever they occur together. The cross with mountain big 



Figure 17. — Black sage- 

 brush (A. nova) growing 

 in shallow, stony soil 

 at Clay Bills Mesa, 

 San Juan Co., Utah. 



18 



