SALICACEAE 51 



obovoid and ^ to ^ inch long. The pistillate catkins, about 

 the same size when in flower, stand on leafy peduncles ^ inch 

 long and at maturity reach a length of ^ to lyz inches. Stami- 

 nate flowers bear 2 stamens, the filaments of which are free, 

 slender, and glabrous or only finely pubescent at the base. 

 Pistillate flowers have short, entire or divided stigmas joined to 

 the ovary by an exceedingly short style. The mature capsules 

 are lanceolate, thinly pubescent with silvery hair, yi to Y^ inch 

 long, and stand on slender pedicels one-sixteenth to 14 inch high. 



Distribution. — The Slender Willow is a northern shrub 

 which inhabits moist alluvial soil and ranges westward from 

 New Brunswick into Saskatchewan and southward to New 

 Jersey in the east and South Dakota in the west. Northern 

 Illinois lies just within the southern limits of its range, and it 

 has been recorded in Cook, Winnebago, Kankakee and Peoria 

 counties. In the Chicago region, it is a shrub of low ground 

 and is generally overlooked, although nowhere is it common. 



Almost without exception, specimens collected in Illinois 

 belong to the variety gracilis Andersson, which is distinguished 

 by its more slender and more graceful twigs, narrower and 

 more sharply toothed leaves, and longer capsule pedicels. 



SALIX HUMILIS Marshall 



Prairie Willow Upland Willow 



The Prairie Willow, fig. 6, is a low shrub, generally only 

 2 to 7 feet, less often 10 feet, tall, with clustered stems bear- 

 ing moderate to stout branchlets and crowded, leathery leaves. 

 The leaf blades vary from linear-oblanceolate to obovate but 

 are chiefly long-oblanceolate and measure 2 to 5 inches long 

 by Y^ to ^ inch wide. They are acute or short acuminate at 

 the tip and narrowed at the base, rich green above with whitish 

 veins and glaucous below, puberulent to glabrous above and 

 more or less tomentose beneath. The veins, beneath, are rather 

 strongly reticulated, and the leaf margins are distinctly revolute, 

 entire to undulate or, more commonly, undulate-serrate. The 

 yellowish brown petioles are moderately stout, pubescent to 

 glabrate, and V^ to ^ inch long. The twigs and branchlets are 

 terete, yellowish, purplish or brown, and pubescent to glabrate. 

 The linear to broadly lanceolate stipules are serrate, acute at 

 the tip, asymmetrically acute at the base, distinctly stalked, 



