Trkks of thk Northern X'nitkd Statk: 



Order, Salicales. 

 , ■ Salicaceae. Willow Family. 



04. Populus L. Poplar. 



Large trees with alternate simple leaves, not 2-ranked and 

 not entire but with gland-tipped teeth ; with 5-angled pith, 8 

 I)undle scars, and terminal, more or less resinous buds with 

 several bud scales. 



Diecious; flowers in aments ; fruit a capsule: seeds with 

 long cottony hairs; leaves mostly with '2 or more glands at 

 or near the base of the blade; twigs prominently self-pruned 

 by means of cleavage planes in basal joints. 



1. Leaves and twigs persistently and densely white tomentose 

 l^elow, usually lol:)ed; self-pruning scars very prominent 

 on the small twigs. P. alba. 



1. Leaves and twigs glabrous or nearly so when old, not 



lobed. 2. 



2. Petioles terete or channeled, not much flattened laterally : 



leaves crenate. 3. 

 2. Petioles strongly flattened laterally. 4. 

 o. Leaves densely tomentose when young often with 2 



small lobes at the l)ase ; capsule slender-pedicelled. /'. 



hrleropJivIla. 

 '■\. Leaves not tomentose l)ut usually somewhat pubescent : 



capsule short-pedicelled. P. balsaiiiifcra. 

 4. Leaves l)roadly deltoid, aljruptly acuminate : terminal 



winter buds usually angular, -y. 



4. Leaves broadly ovate or suborbicular ; lerminal winter 



buds rounded or only slightly angular. 7. 



5. 1>ees of tall, narrow growth with strongly erect l)ranclK's. 



giving a spire-like appearance, young twigs glabrous; 

 leaves usually wider than long, more or less acute at 

 the l)ase. /'. italic a. 



•). Trees with spreading J)ranches. li. 



(). Young leaves pubescent: capsules nearly sessile. P. nuira. 



(i. Young leaves not pul)escent. shinin^^': capsules slender- 

 pedicelled. P. dclioidcs. 



7. Leaves coarsely sinuate-dentate, densely whitc-tomentosc 

 when young, glabrous when mature. P. grandidcntata. 



