354 BOTANY OF CROP PLANTS 



BLACKBERRIES '' 



Only those species are considered in the following keys 

 which have yielded us our important fruit-bearing varieties. 

 The key considers the groups of blackberries as given by 

 L. H. Bailey in "The Evolution of Our Native Fruits." 



Key to Species of Blackberries 



Inflorescences conspicuously loose, the few flowers scattered on long pedi- 

 cels, Rubus nigrobaccus X R. villosus (loose-clustec blackberries or black- 

 berry-dewberry). 

 Inflorescences more compact, the flowers not so scattered along the main 

 axis. 

 Inflorescences leafy, i.e., pedicels subtended by leaves, Rubus argutus 



(leafy-cluster blackberries). 

 Inflorescences entirely or almost leafless. 

 Clusters long. 

 Berries black, R. nigrobaccus (common long-cluster or high-bush 



blackberry). 

 Berries cream-colored or pink, R. nigrobaccus var. albinus (white 

 blackberry). 

 Clusters short. 

 Lower surfaces of leaves white-pubescent; plants i to 3 feet tall, very 



thorny, R. cuneifoUus (sand blackberry). 

 Lower surfaces of leaves pubescent but not whitish; plants i to 8 feet 

 tall, thorny, R. nigrobaccus v&r.sativus (short-cluster blackberries). 



Rubus nigrobaccus. — The tall stems are furnished with strong, hooked 

 prickles. The long-stalked leaves have ovate and distinctly pointed leaflets. 

 Inflorescences are long, glandular-hairy racemes with large, showy flowers on 

 pedicels that stand out almost at right angles. The fruit is firm, oblong, 

 sweet, and aromatic. 



The plant is found throughout eastern United States and northward into 

 Canada. The variety Taylor is the best known. Snyder and Kittatinny 

 are common varieties of the short-cluster blackberries. The white blackberry 

 has greenish-yellow stems and cream-white fruits, and occasionally grows 

 wild. 



Rubus nigrobaccus X R. villosus. — The loose-cluster blackberries are con- 

 sidered to be hybrids between the high-bush or long-cluster blackberry and 

 the northern dewberry. The plants are rather low and spreading and have 

 characteristic, broad, jagged leaflets. 



