324 HETEROMORPHY. 
the two preceding, it was seen that the spire mceluded 
the constituents of seven ordinary verticils. 
Here also may be mentioned a curious bamboo, the 
stem of which is preserved in the British Museum, 
and in which the internodes, on the exterior, and the 
corresponding diaphragms and cavities within are spiral 
or oblique in direction. 
The root is also subject to the same malformation, 
the inducing cause being usually some obstruction to 
downward growth, as when a plant has been grown 
in a small pot, and becomes, as gardeners say, pot- 
bound. 

Fie. 174.—Showing “pot-bound” root twisted spirally (from the 
‘Gard. Chron.,’ 1849), 
The axial portion of the flower, the thalamus, is also 
occasionally twisted in a spiral direction, the lateral 
parts of the flower being in consequence displaced. 
