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IOWA ACADEMY OF SCIENCE Vol. XXIV, 1917 
all penni-nerved, narrowed at the base, broader toward the 
middle, somewhat undulated, lower surface of leaf with scattered 
Pig'. 70. — Trichomes from young plant of swamp white oak ( Quercus 
platanoides ) ; 1, from stem ; 2, from leaf. Drawn by C. M. King. 
pubescence, persistent on the veins, scattered, occurring singly 
or in clusters of two or three, trichomes long pointed, straight 
Fig. 7 i. — Swamp white oak ( Q. platanoides), scales on stem below leaf, 
early and late, fully formed leaf. Photographed May 1, 1917, by Colburn. 
or curved, cell walls thick, contents brown, upper surface with 
trichomes scattered and on midrib, singly or clustered, soon be- 
