Feb., 1913.] The Ohio Dogbanes. 79 



THE OHIO DOGBANES. 



Lillian E. Humphrey. 



Apocynaceae. Dogbane Family. 



Perennial erect or trailing herbs, shrubs, or vines; usually with 

 milky acrid sap. Leaves simple, more commonly opposite, 

 without stipules; flowers hypogenous, sympetalous, tetracyclic, 

 with actinomorphic perianth; andrecium pentamerous, the 

 stamens distinct, united with the corolla at least at the base; 

 pollen not in masses; gynecium of two united carpels, but the 

 ovularies separating below the style; fruit usually two follicles; 

 seeds often appendaged with a tuft of long hairs. 



Key to the Genera. 



1. Flowers solitary, large, axillary; trailing herbs. Vinca. 

 1. Flowers cymose; erect herbs. Apocynum. 



Vinca L. Periwinkle. 



Perennial trailing herbs with opposite, evergreen leaves, and 

 large, solitary, axillary flowers. Stem slightly woody; calyx 

 segments acuminate ; corolla salverformed, blue ; stamens included ; 

 disk of 2 glands alternate with the two carpels; follicles with 

 several ovules and seeds; seeds oblong-cylindric, without hairs. 



Vinca minor L. Periwinkle. Leaves glabrous oblong to ovate, 

 entire, finn, shining, green on both sides, narrowed at the base, 

 short petioled. Escaped from cemeteries and gardens. Huron, 

 Montgomery, Vinton, Portage, Williams, vStark, Wayne, Coshoc- 

 ton, Richland, Auglaize, Lawrence. 



Apocynum L. Dogbane. 



Perennial erect herbs with opposite, entire, leaves and white 

 or pinlc flowers in corymbed cymes. Corolla usually campanu- 

 late, having five small triangular appendages within alternating 

 with the stamens; follicles slender; long, terete, containing numer- 

 ous ovules with tufts of long hairs. 



Key to the Species. 

 1. Corolla much longer than the ovate pointed divisions of the calyx; 

 branches diverging; flowers J4 to 3^2 inch long. 2. 



1. Corolla not longer than the lanceolate divisions of the calyx; branches 



upright, ascending; terminal cyme not extending above the lateral 

 branches; flowers small. 3-16 to 14, inch long. 3. 



2. Corolla campanulate, recurved, not angled, pinkish, narrowed in the 



throat. A. androsaemifoliurn. 



2. Corolla urceolate, five-angled, white or only slightly tinged with pink, 



spreading. A. urceolifer. 



3. Leaves petioled. 4. 



3. Leaves not petioled, lower ones more or less clasping, the upper ones 

 sessile. A. hypericifolium. 



