1914] Flora of the Boston District,— XIX 111 
A. vuLGARIS Hill. Swamps and moist soil, at W. Medford and 
Waltham; edge of saltmarsh at Brookline and Hingham. 
BETULA. 
B. alba L., var. papyrifera (Marsh.) Spach. Dry woods, scat- 
tered trees as far south as Sharon, Hingham and Scituate. 
B. lenta L. Rich woods, frequent except in southeastern portion, 
where it has not been reported. 
B. lutea Michx.f. Rich moist woods; occasional in Essex and Mid- 
dlesex counties, with scattered trees as far south as Canton and Scituate. 
B. nigra L. Moist banks of Merrimac River and lower portions 
of its tributaries from Amesbury west to Tyngsboro and Dracut 
and across the state-line to Pelham, N. H.; also near Parker River in 
Georgetown and Byfield [Newbury], and at Ipswich. A few trees in 
a dry pasture at Groton (C. H. Knowlton, RHopora xiv. 235, 1912) 
are probably introduced. There are no other stations for this species 
nearer than Suffolk Co., Long Island, 115 miles to the southwest. 
B. populifolia Marsh. Dry sandy soil, abundant everywhere. 
CARPINUS. 
C. caroliniana Walt. Wet soil and borders of streams in central 
and northern portions; not reported from southern third of district. 
CORYLUS. 
C. americana Walt. Dry soil; common throughout. 
C. rostrata Ait. Generally distributed in dry soil, but not abun- 
dant. 
OSTRYA. 
O. virginiana (Mill.) K. Koch. Dry rocky woods, frequent. 
: FAGACEAE. 
CASTANEA. 
C. dentata (Marsh.) Borkh. Woods and pastures; abundant in 
many places in western and central portions, much less common near 
the coast and to the southward. 
