204 THl-: PLANT WORLD 



The formation of these new plants in this manner is not 

 spasmodic or exceptional, nor are they fugiti^■e in their na- 

 ture. Under certain conditions they are produced in such 

 numbers as to entirely overshadow the number of seedlings; 

 and they as frequently grow into maturity, producing a plant 

 which, if the origin were not known, would not unlikely be 

 considered a varietal type, in point of habit. Ihe mature 

 plant which had its origin as a seedling, has a single trunk, 

 usually ten or more, sometimes 20-30 centimeters in length; 

 the mature plant produced vegetatively has a very short trunk, 

 or a group of separate ones more or less coalesced by growth. 

 The character of the root system is even more distinct. In 

 the seedling, the tap root may at once be distinguished, while 

 in the form nf root origin there is no tap root. After the new 

 shoot has appeared, the portion of the mother root lying 

 between it and the parent plant retains its small calibre, and 

 fmally dies away from the new growth. Ihe distal portion, 

 however, becomes functionally a tap root, but with its axis 

 at first nearly at right angles to the axis of the new shoot., 

 This position is maintained in spite of secondary changes, and 

 enables one to recognize an individual of root origin even at 

 maturitv- V^ery occasionallv adventitious roots arise from the 

 basal portion ot the new stem, thus adding later elements 

 to the system which ma\ more or less obscure the condition 

 described, and this furnishes a rare exception to the general 

 rule that the guaxulc is unable to produce roots from the stem. 



"I he ratio of the number of new plants arising as seed- 

 lings and of those arising as root-shoots \aries with the 

 habitat. Both forms may be found in any situation, but the 

 retonyos are much more numerous on stony slopes, often A-ery 

 much outnumbering seedlings. The reverse relation is seen 

 in more level places. Thus, at the foot of a low ridge, I have 

 founii as many as thirty small seedlings in a square foot, and 

 larger ones scattered about relati\-elv thickly. A zone of this 

 character could be traced along the ridge. Just above this 

 zone, another could be made out in which the retoin'os were 



