1920] 



DORSEY &• WEISS— PETIOLAR GLANDS 



393 



but since they vary independently on either side of the petiole, 

 their relative position appears to be only incidental. 



Variation in gland position and number 



In horticultural literature, glands have been described with 

 respect to color, type or shape, size, number, and position. In 



Selected instances 



TABLE I 



JSTRATING METHOD OF 



JG DATA AND SHOWING VARI- 



ABILITY OF GLANDS (a) ON DIFFERENT LEAVES WITHIN A VARIETY, (b) WITH 

 REFERENCE TO POSITION ON PETIOLE OR LEAF BASE, (c) WITH REFERENCE TO 



1 



DIFFERENT VARIETIES, AND 



(d) WITHIN SAME VARIETY DURING DIFFERENT SEASONS. 



No. BORNE ON 



Abundance X Wolf 



no. 35 



BURBANK 



BurbankXWolf no. 



Peti- 

 ole 



Leaf 







1914 



IQI7 



IQI4 



191 7 



1914 



1917 



O 



O 



15 

 27 



28 



38 



35 



37 

 1 



40 



33 

 16 







IO 

 16 



32 



. , 



45 

 45 



44 



25 

 28 



52 



44 

 45 







I 



O 



2 



O 



1 



I 



O 



34 

 29 



1 



6 



8 



9 



8 

 29 



25 



1 



65 



47 

 18 



1 



20 



17 



25 



63 



9 



33 

 48 



6 



I 



I 



I 



2 



I 



3 



^■^ 



2 



O 



219 



39 

 4 



188 

 10 



67 

 45 

 33 



141 



49 



1 



161 



2 

 2 



2 



5 



1 



2 



3 







3 



O 



11 

 3 



2 



55 



33 

 12 



33 

 24 



9 

 2 



3 



1 



8 

 6 



4 



3 



I 



x 



3 



2 







4 



O 







7 



3 



1 



2 



1 



1 

 1 







4 



I 



1 





1 



I 



W 



4 



2 







s 



O 











5 



I 











s 



2 











s 



3 











6 



O 







2 















1 





i 

 { 



Slands on 



petiole 



Glands on leaf . 



604 

 143 



491 

 187 



919 

 321 



SOS 

 349 



525 

 220 



437 

 202 



the plum the globose form is the prevailing type, and the true 

 reniform type is found so seldom that little attention has been 

 given to shape. The color of the mature glands in the plum is 

 dark brown; and since these studies of number and position were 

 made on mature leaves, color characters were also not recorded. 



