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meio BY 
88 Structural and Physiological Botany. alee >. 
-cuncial gestivation corresponds to the 3? phyllotaxis. The 
spiral itself may either be a right-handed one, ze. running 
from the left below to the right above, or conversely a left- 
handed one. The law thus indicated is not, however, 
“ , fl z 
= dV / 
SN "a 
a K S 
Fic. 139.— Verticillate leaves of the | 
madder, Rubia tinctorum. 
Fic. 138.—Decussate leaves of the 
scarlet pimpernel, Axagadllis 4 
arvensis, with axillary flowers. Fic. 140.—2/5 phyllotaxis of the oak. 
always easy to recognize in practice. Of the leaves of 
grasses, for example, one half follow a mnght-handed, the 
other half a left-handed spiral. 
The spiral arrangement — 
is often obscured by the leaves standing in a fasciculate 
