Bui. 1038, U. S. Dept. of Agriculture. 
PLATE VII. 
Epidermis and Sections of Pecan Leaves. 
A.— Epidermis of a healthy pecan leaflet collected before sunrise and stained with iodin to show 
the retention of starch in the guard cells, x 540. B.— Vertical section of a pecan leaflet, show- 
ing a calcium oxalate crystal aggregate. X 420. C— Vertical section of a young pecan leaflet 
collected just after emergence from the bud, showing the differentiation of the palisade tissue at 
this early stage of development. Killed in Carnoy's fluid; Fleming's triple stain used. X 540. 
D.— Horizontal section of spongy parenchyma at the margin of a yellow spot, secondary stage, 
stained with iodin to show the presence of starch in the green periphery but a smaller quantity 
or total absence of starch toward the center of the yellow area. X 540*. Photomicrographs by 
the writer. 
