176 Karl M. Wiegand and Arthur J. Eames 



A circumpolar species of the Far North, coming south locally in the U. S. Many 

 forms are in cultivation as ornamental trees, and escape occasionally to woods and 

 thickets. At all the above stations the plant is unquestionably introduced. At Fox 

 Ridge, where it forms a forest of several acres, it seems to have been planted or 

 sown on previously cultivated ground. The cut-leaved forms of this species are 

 var. dalecarlica Schneid. and var. gracilis Rehd. Apparently these forms have not 

 escaped from cultivation. B. pcndula differs from B. populifolia in the more rounded- 

 ovate, less acuminate leaves, less glandular twigs, longer pistillate catkins with longer 

 (3-5 mm.), less divaricate scales, and clustered staminate catkins. The New York 

 State specimens of B. pendida have puberulent pistillate scales. 



[B. alba L. White Birch. 



Occasionally planted, and occurring on roadsides adjacent to the white birch forest 

 at Fox Ridge. Probably not spontaneous. 

 Native of Eu.] 



2. B. papyrifera Marsh. Paper, Canoe, or White Birch. 

 Acid or neutral well-drained soils; rare. May 15-30. 



Not known to Dudley, but clearly native at the top of the high hill 1J miles s. w. 

 of West Danby, where it is abundant. It occurs also in considerable quantity just 

 outside the Cayuga Lake Basin in the n. w. corner of Cayuta Township on the road 

 from Ithaca to Elmira. A single small tree was found in a field, s. side of Fall 

 Creek below Varna. 



Newf. to Alaska, southw. to Pa., Nebr., and Wash., including the northern Atlantic 

 Coastal Plain. 



This species is doubtfully distinct from B. alba L., but in recent years has been more 

 commonly so treated. 



3. B. lenta L. Black or Sweet Birch. 



Rocky or gravelly well-drained acid or neutral soils ; frequent. Apr. 30-May 20. 



Common along the crests of the ravines of the basin, on the cliffs along the shores 

 of Cayuga Lake, and on the hilltops s. w., s., and s. e. of Ithaca. 



Newf. to Ont. and Iowa, southw. to Va., Tenn., and in the mts. to w. Fla. ; rare 

 on the Coastal Plain. 



4. B. lutea Michx. f. (B. allcghancnsis Britton.) Yellow Birch. 

 Rich, usually moist, chiefly neutral soils ; frequent. Apr. 30-May 20. 



The species as a whole is most frequent in the ravines of the basin, in the deeper, 

 cooler woods of the hilltops, and in the McLean region. The typical form is 

 apparently frequent, as about Freeville Bog. 



Newf. to Man., southw. to Del., 111., and Minn., and along the mts. to N. C. and 

 Tenn. ; in the North, common on granitic and other soils. 



4a. B. lutea Michx. f., var. macrolepis Fernald. (See Rhodora 24:170. 1922. 

 B. lutea Britton.) 



Probably of practically the same distribution as the preceding; perhaps less common. 



N. B. to Wis., southw. to Tenn., Ind., and 111. 



In this region there are almost too many intermediate individuals. The fruiting 

 catkins are generally thicker than in the typical form. 



5. Alnus (Tourn.) Hill 



a. Leaves and maturing fertile cones not markedly glutinous (slightly so in no. 1) ; 

 leaves serrate ; shrubs. 

 b. Leaves obovate, acute or cuneate at base, finely and nearly evenly serrate, green 

 beneath; axis of the general inflorescence nodding, but the individual pistillate 

 clusters erect; bark dark dull gray, sparsely lenticellate. 1. A. rugosa 



