10 



MASS. EXPERIMENT STATION BULLETIN 4LS 



Most leaves show some degree of folding, but the amount and type differs 

 with the variety (Figure 5). With some plums, the leaves are usually flat as in 

 Hall. Broad U-folding as in Bavay is very common while narrow U-folding as 

 in Stanley is sometimes found. With some varieties, the upward folding of the 

 leaf seems to be more characteristically V-shaped as in Albion although the 

 dilTerence between U-folding and V-folding is sometimes not uniformly distinct. 

 De Montfort leaves are often saucer-folded while a reverse-saucer folding is 

 characteristic of some varieties such as Burbank. The Bradshaw fold as shown 

 in Figure 5 is very distinctive. It has been the experience of the writers that 

 leaf-folding is a very useful character in identification work. However, it should 

 be emphasized that such a character is profoundly influenced by environmental 

 conditions and much experience is necessary before one can know how much 

 dependence to place on it at any particular time or place. 



Figure 6. Leaf Tip. 



1. MONARCH — mucronate: 



2. YELLOW GAGE — acute: 



5. PEARL 



3. MONITOR — acuminate; 



4. LOMBARD — twisted; 

 reflexed. 



The leaf tip may be of considerable value (Figure 6). Commonly, the tip is 

 acute as in Yellow Gage, but it may be mucronate (very short and abrupt) as 

 in Monarch, or acuminate (long- pointed) as in Monitor. Some tips are charac- 

 teristically twisted as in Lombard or reflexed as in Pearl. Sometimes the point 

 of the tip is a useful character. For example, the point is sharp in Shropshire 

 and dull or round in English Shropshire. 



The leaf margin in plums is rarely even or without any waving as in Monitor 

 (Figure 7). With some varieties, as Albion, the waving is coarse; while with 

 others, as German Prune, it is fine; and many varieties show medium waving. 

 Also, there is wide variation in the amount of aqy kind of waving. This will 

 vary from slight to much and is an important feature to observe along with the 

 type of waving. 



