BETULACEAE 105 



b. Bark yellowish or silvery: leaf-blades dull above : mature bracts with 2 

 ascending lateral lobes: nuts with orbicular-ovate wings. 



5. B. lulea. 



1. Betula populifoUa Marsh. White Birch. (Man. p. 328 ; I. P. /. 

 1211.) In moist or dry soil, N. B. to Ont., Pa. and Del. — Pennsylvania : 

 Northampton ; Monroe ; Schuylkill ; Luzerne ; Susquehanna ; 

 Lackawanna; Pike; Bucks, Spiingfield. 



2. Betula papyrifera Marsh. Paper OR Canoe Birch. (Man. p. 

 328; I. F. f. 1212.) In woods, Newf. to Alaska, northern Pa., Mich, 

 and Wash. — Pennsylvania: Monrok ; Huntingdon; Centre, Bear 

 Meadows ; Luzerne ; Blair ; Tioga ; Lackawanna. 



3. Betula nigra L. RivER or Red Birch. (Man. p. 328; L F. /. 

 ^214.) Along streams and lakes, Mass. to Iowa, Fla. and Tex. — Pennsyl- 

 vania : Northampton ; Lancaster ; Dauphin ; Huntingdon ; Mon- 

 roe; Tioga; Chester. 



4. Betula lenta L. Cherry, Black or SweeT Birch. (Man. p. 

 328 ; I. F. /". J2/5.) In moist soil or on hillsides, Newf. to western Ont., 

 Fla. and Tenu. — Pennsylvania: Northampton; Luzerne; Lancas- 

 ter; York; Franklin; Huntingdon; Fulton; Monroe; Lacka- 

 wanna; Tioga; Pike; Chester; Allegheny. 



5. Betula lutea Michx f. Yellow or Gray Birch. (Man. p. 329 ; 

 I. F. f. 1216.) In woods, Newf. to Man., N. C. and Tcnn., mainly in the 

 h.\\Q%\\^xn^%.— Pennsylvania : Monroe; Dauphin; Lancaster; Hunt- 

 ingdon; Somerset; Pike. 



5. ALNU3 Gaertn. 



Leaf-blades glaucous or finely tomentose beneath. i. A. incana. 



Leaf-blades green, sometimes sparingly pubescent beneath. 

 Leaf-blades finely serrate : foliage not glutinous : species native. 



2. A. rtigosa. 

 Leaf-blades dentate-serrate : foliage glutinous: species naturalized. 



3. A. glulinosa. 



1. A Inus incana (L.) Willd. Speckled OR Hoary Alder. (Man. 

 p. 330 ; I. F./. 1 231.) lu wet soil, Newf. to the N. W. Terr., southern 

 N. Y., Pa. and Neb. Also in Eu. and Asia. — PeJinsylvania : Monroe, 

 Po::ono Plateau; LuzERNE ; Centre; Erie, Presque Isle ; SOMERSET; 

 Lackawanna; Pike; Northampton. 



2. Alnus rugosa (Du Roi) K. Koch. Smooth Alder. (Man. p. 330 ; 

 I. F.y. 1222.) In wet soil or on hillsides, Me. to Minn., Fla. and Tex. — 

 Pennsylvania : Northampton ; Luzerne ; Monroe ; Bucks ; Ches- 

 ter ; Lancaster ; Franklin ; Somerset ; Lackawanna ; Pike ; 

 Allegheny. 



3. Alnus glutinosa (L.) Medic. European AldER. (Man. p. 330 ; 

 I. F.y. 1223.) In wet places, N. Y., Pa. and N. J., escaped from cult. 

 Native of Eu. — Pennsylvania : Northampton. 



