1897.] NATURAL SCIENCES OF PHILADELPHIA. 203 



The young leaves are folded longitudinally. We can see some of 

 the processes by which nature makes Liriodendron differ from Mag- 

 nolia, but what induces the curving of the petiole in one instance 

 and the straightening in another we have yet to learn. 



Though no reference is made of the fact in descriptive botany, the 

 manner in which the base of the petiole folds over the young bud is 

 distinctive of the genus Rhus, or at least, of many species, for I 

 have not examined all. The folding is so nearly complete that no 

 axillary bud is visible. In the winter, after the leaves have fallen, 

 we see by the cicatrices that it was a fold of the petiole and not an 

 absolute over-growth. The cicatrix is precisely like that formed by 

 the fallen leaf of the Horse Chestnut, and adds another suspicion to 

 a list already by no means brief that there is a closer relation be- 

 tween the natural orders Sapindacese and Anacardiacere than sys- 

 tematists generally believe. Other species of trees, notably the Plane 

 and Yellow Wood, have similar embracing petioles. There seems no 

 physiological advantage in these cases. The young bud must have 

 some protection in infancy, and variety seems an essential part of 

 the order of things. All we can say is that this form of protector is 

 as good as any other. The internal arrangement of the bud in Rhus 

 is interesting: Two bud scales meet face to face, and closely press 

 their edges together. The interior is a cavity, but densely filled 

 with short, soft hair. 



A Sapindaceous plant allied to the Horse Chestnut, Kolreuteria 

 paniculata, a small tree from Japan, has branches interesting from 

 the fact that the petiole disarticulates at a little distance above the 

 base of the petiole, leaving lacunose cicatrices, and giving the branch 

 a singular knobby and rough appearance. Here again the teleolo- 

 gist will be at a loss, and seeing that it is no disadvantage, we can 

 only say that it gives a pleasant variation to the run of life. 



I might offer many illustrations, but enough has probably been 

 said to show how much of interest the winter season may afford. 



