ARRANGEMENT OF LEAVES UPON THE AXIS. 195 



nodes between the highest and lowest be undeveloped, these 



leaves will arise from the same point of the branch, still growing, 



however, in their proper directions ; so that a complete circle of 



leaves, resembling that of the leafy parts of a 



regular flower, will be produced ; this is called a 



whorl or verticil. In some instances, however, it 



would perhaps be more proper to consider these 



as leaflets, parts of one leaf; or as so many 



leaves upon one node of the stem. Of such, an 



example is seen in Fig. 75. There are some FlG . 75 . 



plants which exhibit the true spiral arrangement, 



as their regular mode of growth ; others in which we constantly 



find the leaves opposite ; and in some they are always ver- 



ticillate. 



304. But there are many species, which present differences 

 in the arrangement of the various parts in the same individual, 

 according to the circumstances under which each part has been 

 developed ; and it is by such examples that we are able to dis- 

 cern the connection between the several modes of growth. Thus, 

 in the Rhododendron, we find the leaves sometimes opposite, 

 sometimes alternate. In the Honeysuckle, the leaves are natu- 

 rally opposite ; but the pairs are broken up, and the leaves car- 

 ried to a distance from one another, by anything which causes 

 an increased development of the stem ; just as when any leaf- 

 bud (which has the young leaves arranged in a series of whorls, 

 one above or within another) is elongated into a branch. On the 

 other hand, in the Strawberry, the leaves which are usually 

 alternate, become opposite or whorled at intervals. It is to be 

 remarked that, when leaves are opposite, the several pairs are 

 not in a line with one another above and below; but each is at 

 right angles to the next ; so that, if the internode between two 

 pairs were undeveloped, a whorl of four leaves would be pro- 

 duced. Again, when one whorl is developed near another, their 

 leaves do not issue from corresponding points in the stem, but 

 are arranged in such a manner that the leaves of one arise from 

 what seem to be the intervals of those of the other, so that the 

 whorls are alternate to each other. The knowledge of this fact 



