Salix Nigra and Salix Amygdaloides. 431 
which I have classed as pure, might be contaminated with 
nigra, but for the fact that those most stipular are also most 
glaucous, most glandular, and most frequently fragrant, char- 
acters entirely absent from nigra. The leaf-shape of the 
mixed forms follows the various forms of parents, often a 
compromise between the two. The veining appears most 
strongly affected by nigra. 
Issued April 17, 1894. 
