6 MASS. EXPERIMENT STATION BULLETIN 401 



Windsor; while a few varieties such as Gov. Wood, Seneca, Gil Peck, and Early 

 Rivers have heavy pubescence (Figure 7). Upshall (6) lists Black Tartarian, 

 Lambert, Napoleon, and Windsor along with Gov. Wood as having heavy pubes- 

 cence; but the writer has found these four varieties to have consistently less pubes- 

 cence than Gov. Wood and has frequenth' made use of that difference in separat- 

 ing Gov. Wood and Windsor. Pubescence should be determined only on young 

 leaves as it tends to decrease in amount as the leaves become old. 



On the petiole will be found glands which are also very valuable characters of 

 identification. They may vary In size, shape, . color, number, and position. 

 Glands also should be observed on the fairly young leaves as they tend to become 

 shrunken and discolored when the leaves are old. Size and shape vary from small 

 and almost globose as in Yellow Spanish to large and reniform as in Gov. Wood. 

 Gold has an irregular-shaped gland, frequently with a "tail" on the lower end of 

 it. In color the glands may be greenish yellow as in Gold, light as in Yellow Span- 

 ish, pink to reddish as in Schmidt, or red as in Gov. Wood. Glands on the very 

 small young leaves may have somewhat different color than they will have after 

 the leaves have grown to approximately full size. 



The number of glands and their location on the petiole are other characteristics 

 of the variety. Several varieties typically have 2-3 glands; in Schmidt and Victor 

 they are on the petiole near the base of the blade, in Napoleon they are some- 

 what farther away from the base of the blade, while in Yellow Spanish and Gold 

 they are well below the blade on the petiole. Gov. Wood has a moderate number, 

 3-4 somewhat scattered, while Seneca has 4-5 or more, scattered along the petiole 

 (Figure 8). Furthermore, a variety having several glands will frequently show 

 both large and small glands on the same petiole. The writer has not found the 

 character of gland position, i.e., opposite or alternate, to be constant enough to 

 merit its use in identification work. 



Color of the Young Tip Leaves 



If observed while the shoot is making active length growth, especially in the 

 first half of the growing season, the color of the very small young leaves at the tip 

 of the shoot is a valuable character for recognition. During active growth the 

 tip leaves of Gold and Lambert will be light green with only a tinge of red color 

 at the most; Yellow Spanish will be yellowish green; Napoleon will be dull 

 reddish; while Bing will be distinctlj' red. On Rockport the light red color is 

 usually confined to the margin of the folded young leaves. This one character 

 alone is sufficient for accurate separation of Bing, Napoleon, and Lambert, which 

 are frequently found mixed; but it cannot be emphasized too strongly that this 

 character is of value only during active shoot growth. As the tip slackens growth 

 preparatory to the formation of the terminal bud, these color differences disappear. 

 Varieties differ also in the type of green color found in their expanding leaves 

 back of the very tip. Immature leaves of Gov. Wood are light yellowish green, 

 while those of Windsor are darker green in color. 



Leaf Pose 



Leaf pose or the general position taken by the leaves on the upper part of the 

 shoot is characteristic of the variety. Leaf pose involves the amount and t\pe of 

 folding of the blade, the angle of the petiole, and the amount and type of reflexion 

 of the petiole and midrib. In Giant and Napoleon the petiole angle is only mod- 

 erately wide and yet the leaves stand out fairly straight because of a reflexion at 

 the junction of the petiole and midrib. Giant leaves are essentially flat while 

 those of Napoleon are quite folded so that the lower surface of the leaf is in 



