HELIAKTIIUS SUNFLOWER. 179 



An finnual braDcliiug herb, 1 to 3 feet high, haiiy or roughish-pubes- 

 cent. Leaves bipiunatifid, the uppermost simply piuuatifid, smoothish or 

 glabrous above, paler or whitish beneath. 



Habitat. — In waste places everywhere ; a most pestiferous weed. 



Parts Used. — The leaves and tops — not official. 



Constituents. — Both species have a disagreeable odor and an aromatic 

 bitter taste. The leaves of A. trifida are readily eaten by some of the do- 

 mestic animals, but the other species appears to be too disagreeable. Their 

 constituents have not been ascertained. 



Preparations. — They are commonly used in decoction. 



Medical Properties and Uses. — These plants are said to bo stimulant, 

 tonic, and astringent. A decoction has been used, chiefly in domestic prac- 

 tice, as a topical astringent in chronic catarrhal affections. 



Of late years A. artemisicefolia has attracted considerable attention on 

 account of its real or assumed agency in the production of hay-fever. The 

 plant produces pollen in great abundance, which is extremely irritating to 

 the air-passages of many people, and is capable of exciting asthmatic at- 

 tacks in susceptible persons. Now as the weed is so very abundant, and 

 its time of flowering coincident with the greatest development of hay-fevei*, 

 the relation of cause and effect has been asserted by many writers. That 

 it may be so in a certain proportion of cases is quite probable, but that its 

 influence in this direction has been overrated is still more probable. The 

 pollen of all plants is irritating to the air-jjassages of sensitive j^eople, but 

 probabh^ little more so than any other dust of an organic character ; and 

 the proportion which rag-weed pollen in the air of any specified locality 

 bears to that of all other plants combined must be very small indeed. 

 Much less still must its proportion be to other pollen and oi-ganic dust 

 in the au' of cities, where this affection has become endemic — and fashion- 

 able. 



HELIANTHUS. —Sunflower. 



Helianthus annuus Linne. — Common Sunfloxw.r. 



Description. — Heads large, many-flowered, radiate ; the raj'S numerous, 

 neutral, yellow ; the disk-flowers brownish, perfect. Scales of the invo- 

 lucre with foliaceous tips, imbricated in 3 or more series. Eecej)tacle 

 broad and flat, with persistent chatl' which embraces the 4-angled, flattened 

 achenia. Pappus veiy deciduous, of 2 chaffy scales on the principal 

 angles of the achenium, often with two or more smaller intermediate ones. 



A tall rough annual herb, in common cultivation. Leaves alternate, 

 triple-ribbed, ovate, or the lower cordate. 



Habitat. — The sunflower is a native of tropical America, but has long 

 been cultivated hei'e and is sj)aringly naturahzed in waste places. 



Many of the indigenous species of helianthus are but little less strik- 

 ing than this in appeai-ance, and possess similar pi'operties. 



