Feb. .5. 1915 Brachysm 393 



the breaking away of the central pith of the joint. The circular fissure is 

 formed just above the shght ridge or rim that connects the base of the 

 stipules, the position being marked in advance, as already stated, by a 

 narrow zone of smooth skin without any of the hairs and oil glands that 

 are scattered over all of the neighboring surfaces. 



The less definite diS'erentiation of internodes and pedicels in cluster 

 varieties often interferes with the formation of a normal circular fissure 

 for the shedding of the abortive buds, which then remain hanging on 

 the plant. The lower side of the base of the pedicel, the side that faces 

 the main stalk of the plant, is found to be more or less confluent with the 

 surface of the supporting internode. The zone of smooth tissue that 

 indicates the position of the fissure, instead of being circular, may extend 

 far down on the internode ; or all indication of a fissure zone may be lack- 

 ing, so that the pedicel appears as a direct continuation of the internode. 

 The result of such malformations is that the blasted buds, instead of 

 promptly falling off, turn brown and shrivel while still attached to the 

 plant. 



The casual observer is likely to suppose that the shriveled buds have 

 been stricken by a blight, and there is often a strip of dead tissue running 

 down on the internode from the base of the withered bud as though a 

 bacterial or fungous disease were extending along the branch. Though 

 often mistaken for a diseased condition, such injuries are merely the 

 mechanical consequences of the abnormal structure of the internode and 

 the failure to form a properly specialized joint between the internode 

 and the pedicel of the floral bud. The formation of the joint is usually 

 indicated, for the death of the epidermis commonly follows a definite 

 line, even when the bud does not drop off. A complete separation of the 

 underlying tissues allows the shriveled bud to fall away eventually, 

 leaving a long scar extending down the internode, instead of a normal 

 circular scar at the end of the internode. (See PI. LVIII.) 



Decurrent pedicels are not confined to brachytic varieties, but are often 

 found in abnonnal individuals of long-jointed varieties, though usually 

 the internodes that have the decurrent pedicels are shorter, and other 

 indications of abnormality may be present. Thus, in connection with 

 the examples of decurrent pedicels shown in Plate LVIII there is an 

 abnormal inequality in the lengths of the internodes, one being about 

 five times as long as the others.' 



MORPHOLOGY OF DECURRENT PEDICELS 



As already noted, extreme cases are sometimes found in which the 

 pedicels are not only decurrent upon the internodes but seem to lose their 



* A somewhat different interpretation of the decurrent pedicels of tlie cotton plant is presented by 

 Prof. Francis I;. Lloyd. (Lloyd, F. U. Abscission, hi Ottawa Nat., v. ;8, no. ,1/4, p. 41-51, 3 fic-; no. 

 S/6, p. 61-75. 1914) 



