69. Salicaceae 153 



icels; catkin-scales witli silky hairs; stigmas broad; river banks 

 and wt't ground. Cook and Lake counties. Balsam Poplar. 



[P. tacamahaca Mill.] P. balsamijera L. 



1. Petioles strongly flattened laterally, at least near the blade. 



5. Buds pubescent or glabrous, not glutinous; catkin-.scales with 

 silky hairs; .stigmas linear; lea\es dull or gray-green. 

 6. Leaves coarsely dentate, the blades 6-10 cm long, white- 

 tomentose beneath when young, glabrate in age, broadly 

 ovate, the base truncate to broadly cuneate; bud-scales 

 finely appressed-pubescent, glabrate; wooded bluffs in the 

 n. two-thirds of the state. Apr. -May. Large-toothed Aspen 

 P. grandidentata Michx. 



6. Leaves finely crenate, glabrous from the beginning, ovate to 



orbicular, the blades 3-6 cm long; buds glabrous (or mere- 

 ly ciliolate), glossy; thickets and margins of woods; in the 

 central and northern parts of the state, southward to 



Macoupin and Coles counties. Apr. Quaking Aspen 



P. tnmuloides Michx. 



5. Buds viscid, glossy, glabrous; catkin-scales glabrous; stigmas 

 broad; leaves bright or yellow-green. 



7. Leaves rhombic-ovate, cuneate at base, crenate-serrate; 



petioles glandless; branches closely ascending or nearly 

 erect, forming a narrow tree; native of Eur.; cultivated, 



and sometimes found wild. Lombardy Poplar 



- P. nigra var. italica Muench. 



7. Leaves broadly deltoid, mostly truncate at base, coarsely 

 dentate with incuned teeth; petioles usually with a pair of 

 glands at the base of the blade; branches widely spreading, 

 forming a broad-crowned tree; along streams and in low 



ground, common. Mar. -Apr. Eastern Cottonwood 



P. delt aides Marsh. 



2. Salix L. — Willow 



L Scales of the catkins pale green or yellowish, caducous; catkins on 

 short leafy lateral branchlets. 

 2. Style not more than 0.5 mm long. 



3. Ovaries and capsules distinctly pedicelled. 



4. Ovaries and capsules glabrous; leaves lanceolate, petioled, 

 finely serrate; stamens 3-9. 

 5. Capsules 3-6 mm long at maturity. 



6. Mature capsules ovoid-conical, 3-4 mm long; petioles 

 2-6 mm long. 

 7. Leaves linear-lanceolate, green on both sides; com- 

 mon along streams. May. Black Willow 



S. nigra Marsh 



7. Leaves lanceolate, conspicuously glaucous beneath; 

 rare; Madison Co., Eggert, Glatfelter; St. Clair 



