764 



ASCLEPIADACEAE 



Apocynum 



o ~ ' 3o 

 Map 1638 



Apocynum cannabinum L 



50 



Map 1640 

 Apocynum cannabinum 



var cjlabernmum A DC. 



3b. Apocynum cannabinum var. glaberrimum A. DC. Map 1640. 

 Habitats and distribution similar to those of the species. This variety is 

 more frequent than either the species or the pubescent variety. 



Woodson says : "Common in every state in the U. S. and sparingly in 

 Can." 



4. Apocynum sibiricum Jacq. Map 1641. Habitat and distribution 

 similar to those of the other species. Infrequent. 



Newf. and s. Canada, westw. to Wyo., and southw. to Va. and Tex. 



4a. Apocynum sibiricum var. Farwellii (Greene) Fern. Map 1642. 

 A study of our specimens shows several of them to be pubescent on the 

 lower surface of the leaves. Our specimens vary from densely velvety- 

 pubescent to pubescent mostly along the veins with scattered hairs be- 

 tween. Habitat similar to that of the other species. 



Woodson says : "Cent. N. Y., e. Mich., and n. Ind. ; apparently collected 

 in Tex." 



248. ASCLEPIADACEAE Lindl. Milkweed Family 



Erect or decumbent herbs. 



Corona hoods without an incurved horn within G787. Acerates, p. 764. 



Corona hoods each with an incurved horn within 6791. Asclepias, p. 765. 



Twining vines. 



Corolla lobes erect 6812. Ampelamus, p. 769. 



Corolla lobes rotate 6943. Gonolobus, p. 770. 



6787. ACERATES Ell. Green Milkweed 



Leaves many, scattered alternately; sepals about 2 mm long; crown of column 0.5-1 

 mm long; hoods 1.5-2.5 mm long, mostly about 2 mm long 1. A. hirtella. 



Leaves opposite; sepals about 3 mm long, lanceolate, acute (narrower and more acute 

 than those of the preceding species) ; crown sessile; hoods about 4 mm long. 

 2. A. viridiflora. 



