THE WILLOWS OF OHIO. 283 



FRAGILES, CRACK WILLOWS. 



Trees, originally introduced from Europe and though now 

 freely escaped, still largely planted and often found growing in 

 tows (except the Weeping Willow). The bark of the medium- 

 sized branches is smooth, and yellow or greenish as distinguished 

 from the rough brown bark of the Amygdalenae. The leaves of 

 all the species are glaucous beneath and without stipules unless 

 very young. The catkins are borne with the leaves on lateral 

 branches; the stamens are normally only two; the capsules 

 glabrous and green, in flower at least, like the Amygdalenae but 

 unlike the other diandrous willows. 



The Fragiles are clearly intermediate between the polyan- 

 drous tree-willows and the diandrous shrubs. But among them- 

 selves their relationships are not so clear. By hybridisation and 

 the importation of various horticultural varieties the group is 

 very much confused and consists of many very closely similar 

 forms. It has been the despair of many Botanists and one finds 

 more mistakes in the determination of this group than in any 

 other. 



Key. 



From habit. 



Growing in clumps. 



Bark of branches green. 5. fragilis. 



Bark of branches yellowish green or yellow 5. alba. 



Large trees, not in clumps. 



Branches long, drooping. 5. babylonica. 



Branches not pendulous. 



Large branches and trunk disfigured by many ad- 

 ventitious twigs, a tall tree with a central 

 shaft, branches yellowish. S. alba. 



Without many adventitious twigs, a low broad 

 topped tree without a central shaft, branches 

 green. 5. fragilis. 



From leaves. 



Leaves with a marginal vein, reticulations very fine, vena- 

 tion irregular, leaf narrow, acuminate, often strikingly 

 falcate, sharply serrate. 5. babylonica. 



Without marginal, reticulations not so fine, venation regu- 

 ular, leaf broader, not acuminate nor falcate. 



Plate IV. Salix fragilis. 



Leafy twig tpyical of our American form; the single broader leal re- 

 sembles more closely the European form; natural size; caj su!e enlarged 

 three times. 



