34 PROCEEDINGS OF THE ACADEMY OF 



produce frondose branches, the numerical order is lost: branchlets 

 push at any indefinite point along the stem. 



In Chamaecy parts spheeroidea, Spach., the American white 

 cedar, the branching is pretty regular at the fourth node, some- 

 times from the second, rarely from the fifth. 



In Chamsecy parts nutpsensis, Spach., the .yellow cedar of the 

 Pacific Coast, the course is the same as in the American arbor 

 vita. 



Sometimes in very stout shoots of this plant the leaves will be 

 in whorls of three. It is curious to note then that the branching 

 is on the odd numbers; either at three, five, or so on; but yet not 

 in a regular graded series as in its normal condition and in the 

 arbor vitaes. I have counted as many as fifteen nodes without a 

 branch, and this absence of order in branching also exists in 

 junipers. In these the leaves are mostly in threes, though still 

 decussate, and the branching takes place at the odd numbers, and 

 is irregular. 



Callitris quadrivalvis has four leaves in a whorl, and here again 

 we have the irregular branching of the junipers. 



The result of these observations is that in a large number of 

 cases the frequency of branching is in company with declining 

 vigor ; that presence of leaves in an opposite pair is favorable to 

 a regularity of branching on even numbers; and that whorls of 

 three or more are associated with irregular branching on odd 

 numbers. 



It is proper to remark that this branching has reference to the 

 growth of one season. There are axillary dormant buds at every 

 node, which may push according to circumstances during any 

 subsequent year. 



In connection with this subject are some observations worthy 

 of note, though not probabby original. As soon as the branching 

 at alternate nodes begins in Libocedras, Thuja, Biota, and others, 

 the frondose character commences. The pair of adated leaves 

 just above the node which bore a branch, is much contracted. 

 These are always on the upper and lower faces, and are known as 

 the dorsal leaves. The next pair of leaves are more developed, 

 more free from cohesion with the axis, and from one of them a 

 branchlet usually springs. These are the marginal leaves. 

 Usually the branchlets, one from a node and from every second 

 node, are alternate with the ones above and below it ; but when 



[June 25, 



