median lobe representing the apex of the horn which is adnate 

 the entire length of the hood, plane ca 0.5 mm lower than the 

 anther head, the margins with a prominent pair of lateral, 

 basal lobes, the base deeply saccate; fleshy pads bilobed; 

 anther head truncate-conic, 2.2-3 mm tall, 2.2-4 mm wide; 

 anther appendages ca 0.6 mm long; anther wings rounded at 

 base, deeply notched, without spurs, ca 1.5 mm long; 

 corpusculum ca 0.5 mm long; pollinia ca 0.8 cm long. 

 Follicles fusiform, erect on deflexed pedicels, 9-12 cm long, 

 0.7-0.8 cm thick, without tubercles, puberulent to glabrate; 

 seeds broadly obovate, 5-6 mm long; coma tan, 2.5-3.5 cm long 

 (Great Plains Flora Association 1986) . 



3. Diagnostic characteristics: A. stenophylla is best 

 distinguished by its relatively broadly linear leaves, 1.5 to 

 8 mm (.03-. 16 in) wide x 4 - 18 cm (1.62-7.1 in) long and its 

 pale greenish white flowers that are 7.5 - 9 mm (.3-. 35 in) 

 tall. The multiple stems are often prostrate, lying flat on 

 the ground, and the linear leaves are upright, appearing like 

 blades of grass. Occasional specimens of A^_ virdif lora 

 approach this habit, but the leaves are then slightly wider, 

 mostly opposite, and the flowers are larger. The hoods of A. 

 stenophylla are slightly toothed. 



B. Present legal or other formal status 



1. Federal 



A. U.S. Fish and Wildlife Service: none 



B. 



U.S. Forest Service: 



none 



Bureau of Land Management: none 



2. State: The species is 

 given a state rank of "SI" 

 indicating that it is 

 critically imperiled. 



Geographical distribution 



1. Species range: Western 

 Illinois to southeastern 

 Montana, south to Colorado, 

 western Arkansas, Texas. 



2. Montana distribution: 

 Narrow-leaved milkweed is only 

 known from Carter County in the 

 state, including one 

 population in the Long Pines 

 and one on Chalk Buttes. 



22 



497. .4 ulrpias \tennphytla Gray 



Niirn.w-lc;.ved Milkweed 



