2.j4 saltcace.e. 



A verj' large genus of slirubs ami trees, growing cliiefl} along water- 

 courses in the northern temperate zone, but some inhabit high mountain", 

 and one is found nearer tlie nortli pole than any other shrubby j)l!i';.. All 

 known sjiecies are bitter, and contaiii xalicii) in a greater or 1(!S' proportion. 

 The one in which this principle is most abundant, and which has therefore 

 been chiefly employed medicinally, is : 



Salix alba Linne. — Mltilc Willow. 



JJr.-iCj'ip/ion. — Catkins long, loose, pedunculate, borne on the summit of 

 the lateral leafy branches of the season. Scales entire, greenish-yellow, 

 more or less hairy, falling before the pods are ripe. Stamens mostly 2 ; 

 filaraents hairy below. Ovary short-stalked or nearly sessile, glabrous ; 

 stigmas thick, recurved. 



A tr e, 50 to 80 feet high. Leaves lanceolate or elliptic-lanceolate, 

 pointed, somewhat toothed, clothed more or less with white, silky hairs, 

 esi^ecially beneath. 



Habitat. — Iuh\.Juced from Euroj)e, but naturalized and very eommon 

 in moist situations. 



The indigenous species of willow are very numerous, and many of them 

 are very common, but, as few of them have ever been employed medicinally, 

 they need not occnjn- our attention here. 



Part Used. — Tlie bark of salix alba and of other species of salix. — 

 United States Pharmacoixxda. 



Constituent.^. — Willow bark contains as its most important constituent, 

 salicin. This, as remarked above, has been found in all species which have 

 been examined. On this account the Pharmacopa'ia recognizes not only 

 salix alba, but "other species." The bark also contains considerable tan- 

 nin, and common vegetable princij^les. 



Preparation f>. — None ai'e official. It has been employed in powder, de- 

 coction, and infusion. The active principle, salicin. is the most eligible 

 and efficient form in which to employ it. 



lledical Properties and Uses. — Willow bark is tonic and antiperiodic. It 

 has been used in intermittents, and as a tcniic in dyspepsia, debility, and 

 convalescence. Eecently salicin has been employed with asserted benefit in 

 rheumatism. 



I'OI'ULUS.-Popi.ATi. 



Cliaractcr of the Genus. — Si'alcsof the catkins j igged or iiregularly cut- 

 lobed at the apex. Flowers in a cup-shaped disk ; the staminate with 4 to 

 150 stamens ; the pistillate of a single pistil. Trees with broad, more or 

 less cordate leaves, the petioles often compressed laterally, thus occasion- 

 ing a tremulous motion when the least agitated. Catkins long and drooj)- 

 ing, appearing before the leaves, 



Populus tremuloides Michaux. — American Aspen. 



Description. — Scales of the catkins in 3 or 4 linear divisions, fringed 



