(;c MASS. EXPERIMENT STATION BIH-LETIN 274 



pubescence of sluK)t and prominence of hud support in the plum. 



Not all the work of. this nature has been confined to tree fruits. Grubb 

 (11) has studied tin- characteristics of the new canes and fruiting canes 

 of raspberry varieties in England; while Winter (28 and 29) presents a 

 kej to the varieties grown in Minnesota based upon presence and posi- 

 tion of glands, form of leaflets, and form, quantity, and color of bristles. 

 Ir! the case of currants, Thayer (;22) has formulated a key using foliage 

 characters, while in his later publication (23) flower, fruit, and foliage 

 characters are used to separate varieties of red and white currants into 

 several fairly distinct groups. Maynard (12) has attempted a classifica- 

 tion of strawberry varieties using position of hairs on the petiole, color of 

 .stipules, color of foliage, surface of leaflet, curvature of the lamina and 

 leaflet, and other plant, flower, and fruit characters. 



Tree Characters 



The varietal characters of growth, bark, bud, and wood are of great 

 value in recognizing varieties from the non-bearing trees. One depends 

 on them in about the same degree as on the leaves. When the trees are 

 dormant they are, of course, the only characters available. M'iule they 

 arc then more distinct than in actively growing trees, yet identification is 

 less positive with dormant trees than with those having leaves. 



Size and Vigor 



The size of an individual tree dejiends mostly on age and on soil and 

 other environmental conditions; yet there are size difl'erences that are of 

 great value in recognizing varieties. Williams is likely to be smaller than 

 most other varieties. Arkansas and Fall Pippin under mo.st conditions 

 niake large trees. Often a stray tree or grouji of trees in the nursery 

 row is betrayed by a size ditference. In the rather common mixture of 

 Staynian and Winesap, the larger Stayman trees often show up in a 

 striking manner. Too much stress should not be placed on size of "tree, 

 however, for trees all of one variety often contain individuals varying in 

 size so as to suggest a mixture. 



Form or Shape of Top 



Trees that are two years old or older show differences in the form of the 

 to]i that are characteristic of the variety. Form de))eiuls largely on the angle 

 formed by the nuiin branches and the trunk or axis of the tree and on the 

 amount of curvature of these main branches. If the branches show little or 

 no curvature, the top is said to be diverymii. Depending on the branch angle, 

 the form may be said to be varroidy divenjituj as in Sutton, moderately di- 

 vertiiiKj as in Northern Spy, or broadh/ diverging as in Staynian. In a similar 

 way those varieties having distinctly curved main branches are said to be 

 iKirro'idii upruri'ind (Wagener), modcrafeli/ upcurvin<j (Red Astrachan), or 

 hrotidhi Ufirurvi)i(i (Gravenstein). 



