Amelanchier 



ROSACEAE 



531 



The species is variable in the shape, size, and juiciness of the fruit. The 

 common form has fruit which is nearly dry and is smaller than the juicy 

 form. 



Newf. to Mich., southw. to Fla. 



3343. AMELANCHIER Medic. Shadblow 



[Wiegand. Amelanchier in eastern North America. Rhodora 14: 117- 

 161. 2 pi. 1912. Wiegand. Additional notes on Amelanchier. Rhodora 

 22: 146-151. 1920.] 



The species of this genus are known to hybridize and because of this 

 fact the determination of specimens is often difficult. K. M. Wiegand, 

 who has made the most exhaustive study of the genus of anyone in the 

 United States, has named nearly all of my specimens which include several 

 hybrids. He says for accurate determination "collections should be made 

 from the same plant at flowering time just as the petals begin to fall, 

 at the time when the fruit is half grown, and at the maturity of the leaves. 

 Mature ripe fruit is nearly worthless. The mature leaves are not absolutely 

 necessary, but the other two collections are indispensable." The follow- 

 ing key is adapted from his publications : 



Teeth of leaves coarse (on average leaves 3-5 (6) per cm); veins conspicuous, usually 

 straight, parallel and close together, short intermediate ones few or none; sum- 

 mit of ovary woolly; sepals revolute from the middle at the time when the petals 

 fall; leaves rounded, obtuse or subacute at the apex. 

 Petals 7-10 mm long; sepals 2-3 (4) mm long; racemes erect or nearly so; leaves 

 oval-oblong; veins usually becoming irregular just before reaching the margin; 

 stiffly upright shrubs 0.3-1.2 m high, growing in colonies (not in clumps) from 

 rhizomelike bases; margins of leaves serrate to below the middle. .1. A. humilis. 

 Petals 11-20 mm long, narrow; sepals 4 mm long; racemes more or less drooping; 

 leaves oval-orbicular; upper veins, in typical specimens, running straight to the 

 apex of the coarse, spreading, sharp teeth; scrawny, slender, often arching 

 shrubs, 1-2.5 m high; stems solitary or few together; margins of leaves serrate 

 nearly to the base. (See excluded species no. 311, p. 1059.) A. sanguinea. 



