JSS Miller The DM/IHIH<-* of tin- District nf < blumbia: 



Apocynum album Greene. 

 (PI. II, Fig. 5.) 



1881. Apocynum cannabinum var. glabcrrimum Ward, Guide to Flora of 

 Washington and Vicinity (Bull. 22, U. S. Nat. Mna.), p. 97 (not 

 of De Candolle, 1844). 



1897. Apocynum album. Greene, Pittonia, 111, p. 230. December, 1897. 



1898. Apocynum cannabinum fflaberrimwm Britton and Brown, 111. Flora, 



N.' United States, Canada and Brit. POSH., Ill, p. 3 (not of De 

 Candolle, 1844). 



Type locality. Shore of Potomac River, near Chain Bridge, Montgomery 

 County, Maryland. 



Geographic distribution. The range of Apocynum album is not well un 

 derstood. Britton and Brown say, " range apparently nearly of the type, 

 but more abundant northward." I have examined specimens from va 

 rious points in Maryland along the shores of the Potomac River from Old 

 Town to Marshall Hall, also from mouth of Tucquan Creek, Lancaster 

 County, Pennsylvania ; Stratford, Connecticut ; and Ithaca, New 7 York. 



Zonal position. Probably confined to the Upper Austral and Transition 

 zones. 



Habitat. Beaches and river shores. 



Characters. Like Apocynum cannabinum Linnaeus, but of more slender, 

 branching habit, and with smaller, much narrower leaves and essentially 

 white flowers. The largest leaves are about 110 mm. in length by 20-.'U) 

 mm. in brea'dth, those of the upper part of the plant much smaller (about 

 60 x 15). They are oblong-lanceolate in form, those of the upper part of 

 the plant acute at each end, those of lower part of plant rounded at base. 

 All are mucronate tipped and wholly glabrous throughout. Petioles 2-3 

 mm. in length. Stems green, very slightly purple tinged, slender and 

 much branched, the branching more profuse than in A. cannabinum, but 

 of the same character. Inflorescence in terminal irregular cymes never 

 as large as those commonly met with in A. cannabinum. Calyx lobes 

 about as long as corolla tube or slightly shorter. Corolla about 4 mm. in 

 length, white, often faintly tinged with green, pentagonal, short tubular 

 or faintly campanulate, the upright lobes slightly more than half as long 

 as tube, rounded at tips. Pods about 125 mm. in length. Rootstock 

 horizontal, perennial, widely branching. 



Remarks. Apocynum album is so different from A. cannabinum as to re 

 quire no very close comparison. The peculiar character of its habit, 

 leaves, and inflorescence sharply differentiate it. The white or nearly 

 white flowers, however, are not, taken alone, diagnostic, as forms of A, 

 cannabinum frequently occur in which the corolla is equally white. 



This plant appears to be strictly confined to beaches and river ' bot 

 toms.' Near Washington it occupies, to the exclusion of other members 

 of the genus, the flats and islands of the Potomac, seldom if ever growing 

 on land that is not flooded at high water. Mr. K. A. Preble has sent me 

 specimens from a small island in the Potomac at Oldtown, Maryland, and 

 Mr. Win. Palmer has collected it at Marshall Flail. 



