432 COXTRIBUTIOXS FROM THE NATIONAL HERBARIUM. 



•dense clumps, slightly hairy; leaves alternate, divided into narrowly linear lobes; 

 heads 1 or few, 8 mm. high; flowers yellow; pappus of 5 scales. 



From a closely related species of Colorado, rubber was for a time extracted upon a 

 commercial scale. 



19. GAILLARDIA Foug. 



1. Gaillardia arista ta Pursh. Beown-eyed Susan. Common on the east slope 

 at low and middle altitudes, infrequent on the west slope, but found at Belton and 

 doubtless elsewhere; on prairie or open slopes; occasionally growing on slopes above 

 timber line. B. C. to Oreg., Colo., and S. Dak. — Perennial, 30 to 60 cm. high, hairy; 

 leaves oblanceolate, entire or more ccmmonly toothed or lobed; heads Icng-stalkfd, 

 the involucre 2 to 3 cm. broad, the rays 2 to 3 cm. Icng, bread, 3-lobed, yellow, often 

 purplish at the base; disk flowers brownish purple. 



A handsome plant, often cultivated under the name of blanket-flower. The culti- 

 vated plants are scarcely superior to some of the wild ones in the size of their heads. 



20. ACHILLEA L. 



1. Achillea lanulosa Nutt. Yarrow. Common, especially at high and low alti- 

 tudes, in meadows or on rock slides, open slopes, or prairie. B. C. to Calif., Mex., 

 Sask., and Ont.— Perennial, 15 to 50 cm. high, with a strong odor, silky-hairy; leaves 

 alternate, also in basal tufts, 3 to 10 cm. long, plumelike, 2 or 3 times divided into 

 numerous small narrow lobes; heads 4 to 5 mm. high, in flat-topped clusters, the bracts 

 with brown borders; rays 2.5 to 4 mm. long, white, rarely pink; pappus none. 



Yarrow is one of the common plants in nearly all parts of the United States. The 

 leaves are very handsome. 



21. MATRICARIA L. 



1. Matricaria matricarioides (Less.) Porter. Pineapple-weed. Frequent on the 

 east slope at low altitudes, in waste ground or on open slopes or prairie. Alaska to 

 Calif., Ariz., and N. Dak.; also in Eur. (Chamomilla .niaoeolens Rydb.) — Annual, 

 nearly glabrous, 5 to 30 cm. high, usually much branched; leaves alternate, 2 or 3 

 times divided into short linear lobes; heads without rays, 6 to 8 mm. broad, the 

 disk rounded; bracts thin, with whitish margins; flowers greenish yellow; pappus 

 an inconspicuous crown. 



The plant has a strong but not unpleasant odor. The dried flowers were used by 

 the Blackfoot Indians as a perfume. 



22. CHRYSANTHEMUM L. 



The cultivated chrysanthemums belong to this genus. 



1. Chrysanthemum leucanthemum T>. Ox-eye daisy. Occa.sional about Belton, 

 on brushy slopes or in waste ground. Native of Eur.; naturalized as a weed in 

 N. Amer. {Leucanthemum leucanthemuvi Rydb.) — Perennial, 30 to 100 cm. high, 

 glabrous; leaves linear to obovate, toothed or lobed; heads long-stalked, the involucre 

 about 1.5 cm. broad, the bracts ^vith a narrow brown band near the margin; rays 

 white, 12 to 15 mm. long. 



One of the commonest weeds of the eastern States, but rare in the Rocky Mountains. 



23. ARTEMISIA L. Wormwood. 



Herbs or shrubs, usually perennial, with aromatic odor and bitter flavorf leaves 

 alternate, usually white-woolly; heads small, panicled, without rays; achenes usually 

 glabrous, without pappus. 



Plants shrubby. Leaves linear, entire 1. A. cana. 



Plants herbaceous. 

 Leaves glabrous . 



Leaves divided into numerous linear lobes 2. A. biennis. 



Leaves linear, entire 3. A. dracunculoides. 



