DUPLICATION AND COHESION IN THE MAIN AXIS 

 IN CICHORIUM INTYBUS 



A. B. STOUT 



New York Botanical Gardett 



The terms duplication and cohesion may be used to designate a 

 very special type of fasciation which the writer has observed in the 

 variety of chicory cultivated under the name "red-leaved Treviso." 

 The most distinctive characteristic of this type of fasciation is the 

 duplex nature of the main axis. From a single root a double 

 stem arises with the two parts, as a rule, strongly united. The 

 duplex nature is indicated by a pair of grooves which extend in the 

 direction of the long axis and round out the two stem-elements. This 

 is quite well shown in number 5 of the accompanying plate XII. 



This type of fasciation differs from the banded and cone types 

 most usually seen in that here two stem-elements of equal size and 

 rank are clearly in evidence throughout a segment of unequal 

 diameters, giving a symmetry that is bilateral. Also the fasciation 

 is confined to the middle and lower portions of the stem and decreases 

 upwards, the main axis often becoming at its apex quite symmetri- 

 cally simplex. 



I have been unable to find in the literature any reference definitely 

 mentioning fasciation of this particular type. It appears not to have 

 been noted and described even in this rather well-known variety of 

 chicory. 



In the degree and the extent of the duplication there is much 

 variation. The most extreme condition of duplication is seen in the 

 complete separation of the two stem-elements with each perfectly 

 formed and without lesions, as is shown in no. 7 of Plate XII. In many 

 cases the two elements are indicated only by grooves which extend 

 from close to the base of the plant to a height of about three feet. 

 The length of the grooves and the corresponding segment of evident 

 duplication may, however, be reduced to mere traces, as is shown in 

 no. 3 at a or in no. 4 from a to b, as indicated. In a few plants of 

 this strain there is no evidence of duplication and the phyllotaxy is 

 of a single and regular spiral only. 



Each stem-element has its own phyllotaxy in so far as this can be 

 expressed. In the most pronounced duplex condition there are clearly 

 two separate spirals in evidence. The phyllotaxy of one is not a 



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