408 MISC. PUBLICATION 42 3, U. S. DEPT. OF AGRICULTURE 



Sometimes erroneously called "burrobrush." It is browsed by 

 sheep and goats, to a lesser extent by cattle, and withstands heavy 

 browsing successfully. The plant is described as apetalous and is so, 

 normally, but a specimen collected in Mohave County {Kearney and 

 Peebles 11219) had two pale yellow obovate petals opposite to and 

 considerably longer than the outer sepals. 



18. PURSHIA. Antelope-brush 



Shrub, intricately branched, erect or sprawling; leaves fascicled, 

 small, tomentose, with wedge-shaped blades 3-toothed at apex; flowers 

 solitary at the ends of the branchlets; sepals and petals 5, the petals 

 yellow; stamens many, in one series; disk none; pistil usually solitary 

 (sometimes 2, rarely 3); style stout, beaklike. 



1. Purshia tridentata (Pursh) DC, Linn. Soc. London Trans. 12: 158. 

 1817. 



Tigarea tridentata Pursh, Fl. Amer. Sept. 333. 1814. 



Apache County to Coconino County, 4,000 to 9,000 feet, open 

 slopes and mesas and in coniferous forests, April to June. Montana 

 to British Columbia, New Mexico, northern Arizona, and California. 



Also known as bitterbrush. A very important browse plant for 

 sheep and cattle in regions where it is more abundant than in Arizona. 

 The often prostrate stems, rooting where they touch the ground, 

 doubtless give this plant value for control of soil erosion. 



19. AGRIMONIA. Agrimony 



Plants herbaceous, perennial; stems erect, leafy, usually branched 

 above; leaves alternate, with conspicuous stipules and odd-pinnate 

 blades, the leaflets alternately large and small, serrate-dentate; 

 flowers numerous, small, in long slender spikelike racemes; hypan- 

 thium obconic to hemispheric, with hooked bristles; petals yellow; 

 stamens 5 to 15; achenes 1 or 2. 



Key to the species 



1. Bristles of the hypanthium (at least the outer ones) strongly reflexed at ma- 

 turity; leaflets oblong or ovate-oblong, scarcely acuminate at apex, thin, 

 sparsely pubescent to glabrate beneath 1. A. gryposepala. 



1. Bristles all erect, or the outer ones ascending-spreading at maturity; leaflets 

 lanceolate or oblong-lanceolate (seldom broader), acuminate at apex, 

 usually thickish and copiously pubescent beneath 2. A. striata. 



1. Agrimonia gryposepala Wallr., Beitr. Bot. 1: 49. 1842. 

 Coconino County, at Walnut Canyon (Leiberg 5791), and Oak 



Creek (Fulton 7332), about 6,000 feet, August and September, appar- 

 ently rare in Arizona. Almost throughout North America. 



2. Agrimonia striata Michx., Fl. Bor. Amer. 1: 287. 1803. 

 Apache County to Coconino County, south to Cochise and Pima 



Counties, 7,000 to 8,500 feet, frequent in rich soil in pine forests, July 

 to October. Nova Scotia to British Columbia, south to West Vir- 

 ginia, New Mexico, and Arizona. 



