344 Karl M. Wiegand and Arthur J. Eames 



b. Cauline leaves oblong-lanceolate, very short-petioled, rounded, truncate, or 

 slightly cordate at base; venation irregular; branch leaves elliptic-lanceolate, 

 often narrowly so; corolla 2.5-2.9 mm. long; sepals 1-1.5 mm. long; follicles 

 6-12 cm. long. 2. A. cannabinum 



b. Cauline leaves oblong, more often obtuse, almost or quite sessile and clasping 

 by a cordate base ; venation closer and more pinnate ; branch leaves longer, 

 oval-lanceolate; corolla 2.9-4 mm. long; sepals 2-3 mm. long; follicles 12-17 

 cm. long. 

 c. Foliage glabrous. 2a. A. cannabinum, 



var. hypericifolium 

 c. Foliage pubescent. 2b. A. cannabinum, 



var. pubescens 



1. A. androsaemifolium L. Spreading Dogbane. Wandering Milkweed. 

 Dry sandy or gravelly thickets and clearings, in slightly calcareous or noncal- 



careous soils ; common, and generally distributed. June 20-July. 



Newf. to B'. C, southw. to Ga., Mo., and Ariz., including the Atlantic Coastal 

 Plain. 



2. A. cannabinum L. Indian Hemp. 



Gravelly shores of lakes and streams, rare or absent in noncalcareous soils; com- 

 mon. July. 



Occurring in great profusion on gravel bars in streams of the basin and on 

 gravelly beaches along Cayuga Lake. 



Newf. to Wis., southw. to Ala., Miss., and Kans., including the Coastal Plain. 



The leaves of this plant are nearly always glabrous. 



2a. A. cannabinum L., var. hypericifolium (Ait.) Gray. Indian Hemp. 



Gravelly or sandy banks near streams or ponds, usually in finer and richer soil than 

 the. preceding ; common, at least at lake level. Xune 20-July. 



Railroad, near Lick Brook; near mouth of Buttermilk Glen; Red Mills; Union 

 Springs; Cayuga Bridge; edge of Salt Pond w. of Howland Island; border of Crusoe 

 Prairie ; marly moor of Newton and Lowery Ponds. 



Que. to Sask. and B. C, southw. to w. Me., cent. N. Y., Ohio, and Colo. ; infre- 

 quent or scarce on the Atlantic Coastal Plain. 



2b. A. cannabinum L., var. pubescens (R. Br.) DC. 



In situations similar to the preceding ; scarce. 



Railroad bank s. of Buttermilk Creek ; marly moor of Lowery Ponds. 



R. I. to Ont. and Iowa, southw. to Ala. and Mo. ; frequent on the Coastal Plain. 



In various localities in the Cayuga Lake Basin are found plants which answer 

 to A. Milleri Britton, to A. urceolifcr Miller, and possibly to A. medium Greene. 

 In certain places, as for example along the rocky lake shore near Portland Point 

 and Atwater, great masses of such forms occur. These forms, though constant 

 in each locality, differ considerably in the different localities. In every instance 

 they seem to combine characters found in A. androsaemifolium and A. cannabinum, 

 but to present no new characters themselves. It seems wise at present to consider 

 them of hybrid origin. Two principal types have been noted, as follows : 



(a) A form approaching A. urceolifcr Miller, with long sepals equaling the tube of 

 the corolla, and with glabrous foliage: gravelly bank by pumping station, Six Mile 

 Creek (E, L. Palmer, also A. J. E. & L. H. MacDanicls). 



(b) A form approaching A. Milleri Britton, with short sepals and glabrous leaves: 

 shale cliffs s. of Portland Point; shale talus along cliffs n. of Atwater. 



In both forms the corolla is distinctly more pinkish or more nearly pure white 

 than in the greenish-white-flowered A. cannabinum and its varieties. 



