230 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 



1. APOCYNTJM L. Dogbane. 



The representatives of this genus in our region have been treated at length by 

 G. S. Miller. 1 Hia conclusions as to specific limits and the use of specific names 

 are, however, widely different from those of the present treatment. Besides the 

 species recognized below, Miller also reports Apocynum androsaemifolium L. as 

 collected between Sligo Branch and Paint Branch. The writer has seen no speci- 

 mens of that species, which is distinguished from our others by its large pink corolla 

 about 8 mm. long. 



Leaves perfectly glabrous beneath. Branches opposite; corolla greenish white, the 

 lobes erect. 

 Leaves short-petioled, narrowly lance-oblong, very acute, usually less than 2 cm. 



wide, often acute at the base; corolla nearly white 1. A. cannabinum. 



Leaves, at least the lower ones, sessile, broadly oblong or ovate, usually 3 cm. wide 



or larger, rounded at the base; corolla greenish 2. A. sibiricum. 



Leaves more or less hairy beneath. 

 Corolla greenish, the lobes erect; main stem ending abruptly in a cyme of flowers, 

 the lateral branches continued above; leaves usually densely hairy beneath. 



3. A. pubescens. 

 Corolla white or pinkish, the lobes slightly spreading; branching dichotomous, that 

 is, the stems forking; leaves densely or only slightly hairy beneath. 

 Cymes small, rounded; corolla 4-6 mm. long; branches, at least the upper ones, 



reddish f 4. A. medium. 



Cymes broad, flat-topped; corolla 7 mm. long; branches usually green, ascending. 



5. A. speciosum. 



1. Apocynum cannabinum L. Indian hemp. 

 Low ground or in marshes, chiefly along the Potomac; common. May-Aug. 



Widely distributed in N. Amer. (A. album Greene.) 



A, album was described from plants found along the Potomac. The bark of A. 

 cannabinum contains a strong fiber, which was used by the Indians for various pur- 

 poses. 



2. Apocynum sibiricum Jacq. 



Low woods and fields; frequent. May-Aug. Widely distributed in N. Amer. 

 A. hypericifolium Ait.) 



3. Apocynum pubescens R. Br. 



Open woods, thickets, and fields; abundant. June-Sept. Eastern N. Amer. 

 (A. cannabinum of Miller, not of Linnaeus; A. cannabinum pubescens DC; A. canna- 

 binum pubemlumB&g. & Bel.; A. nemorale Miller; A. cannabinum nemorale Fernald.) 



The type of A. nemorale was collected at the Virginia end of the Chain Bridge. 



. Apocynum medium Greene. 



Dry fields; frequent. Juno-Aug. Northeastern N. Amer. (A. urceolifer Miller; 

 A. milleri Britton; A. pseudomcdium Beg. & Bel.) 



The type of A. urceolifer was collected at Capital View Park; that of A. milleri 

 also is from our region. 

 6. pocynum speciosum Miller. 



Fields and roadsides; frequent. June-July. Range not definitely known. 



The type was collected between Silver Spring and Sligo Branch. 



2. VINCA L. 

 1. Vinca minor L. Periwinkle. 



Roadsides and woods; frequent. Apr. Native of Eur., often cultivated; fre- 

 quently escaping and becoming naturalized. 



Known also as myrtle. White-flowered plants are sometimes found. 



Proc. Biol. Soc. Washington 13: 79-90. pi. 2. 1899. 



