WALNUT LEAF WITH PINNAE REPLACED BY STIPULES 



Figure 11. A late-growth leaf of "Royal" walnut, at Bard, California, September, 

 1922, with an upper pair of pinnae replaced by small stipule-like organs. Other leaves 

 of the same tree showed other ipairs or single pinnae replaced in the same way, in- 

 cluding cases of the uppermost lateral pinnae so replaced, which seems to prove that 

 the small stipule-like organs are structural equivalents of the pinnae, and indicates 

 the possible derivation of the pmnac through reduplication of stipules. (Natural size). 



