148 IOWA ACADEMY OF SCIENCES. 



The stout twigs vary in color from oracge-red to purple and 

 are usually densely pubescent when young. The buds are 

 large, four lines or more long, ovate, and reddish-purple. The 

 leaves reach an extreme length of five inches and a width of 

 one and one-half. This species is quite readily recognized by 

 the broad, densely glossy-villous aments which appear very 

 early in spring on the yet leafless branches. The staminate 

 aments of -S*. cordata, before they are fully expanded, are mis- 

 taken for those of this species. They have, however, more of 

 a wooly appearance than of the silvery silkiness of S. discolor- 

 and are not as large. The scales in discolor are large, oblong 

 or ovate, deep red, and copiously long- villous. The pistillate 

 aments reach a maximum length of one and one-half inches 

 and a width of three-fourths of an inch. The staminate are 

 smaller. Capsules are three to five lines long. The flowering 

 period in Iowa is from the tenth to the last of April. 



Spirit Lake, Dickinson Co. 4, SMmek, S. U. L; Armstrong', Emmet Oo. 5, Cratty, 

 Herb.; Mason City, Cerro Gordo Co. 12, Shimek, S, U. 1.; Clermont, Fayette Co. 17, 

 Walker: Fayette, Fayette Oo. 18, Fink, Herb, (var, priiioides); Delaware Co. 33, Cameron 

 (2 specYiS.U. 1 ; Ames, Story Co. 28, Benton, Bessey, Hitchcock (2 spec.) Stewart, Sample (No. 

 1193), Pammel (No. 1194, var. prinoides), Ball (No. 1195), Ball & Sample (No. 1196); Clinton 

 (Lyons), Clinton Co. 33, Pammel; Iowa City, Johnson Co. 86, Hitchcock, Shimek, S. U. I.; 

 Solon, Johnson Co. 37, Shimek, S, U. I. ; Blue Grass, Scott Co. 40, Barnes & Miller (No. 8), 

 Miss Benshoof (No. 4) ; Muscatine 41, Beppert (Nos. 453, Hi, vii, and ten others) Herb.; Mt. 

 Pleasant, Henry Co. 44, Mills, Herb,; Steamboat Rock, Pammel <fc Hume (1946 P). 



VII. SALIX HUMILIS MARSH. 



Salix humilis Marsh. Arb. Am. 140. 1785. 



The prairie willow is a common species throughout our 

 state, inhabiting uplands and dry soils, and reaching a height of 

 two to ten feet. The twigs when very young are greenish, but 

 as they become older they vary through orange-red to deeper 

 hues and finally become gray. The leaves are sometimes 

 nearly or quite glabrous below when mature. Occasionally 

 broad forms are found on vigorous shoots which resemble the 

 leaves of S. discolor. Hybrids of these two species do undoubt- 

 edly occur but these vigorous shoots are found on shrubs 

 which are otherwise typical S. humilis. Normal leaves vary 

 from one and one-half to three inches long, with an average 

 width of one-half inch. The staminate aments are smaller 

 and more slender than the pistillate. The latter are from one- 

 half to three-fourths of an inch long, and dense. The cap- 

 sules are from three to four lines in length. Flowering period 

 from April 10th to May 10th. 



