174 The Ohio Naturalist. [Vol. II, No. 3, 



Several varieties of the cultivated grape, Vitis labrusca L,., 

 were observed to prune themselves to a limited extent by the 

 formation of transverse joints, corresponding to the leaf nodes, 

 in the same way as was described for Ampelopsis cordata j\Ix. 

 This is also true for the common riverside grape, Vitis vulpina 

 L., which prunes itself quite extensively. It is probable that all 

 of our wild grapes possess the process of self-pruning, although 

 no further observations have been made ou this point by the 

 writer. 



In this place it may be well to call attention again to the for- 

 mation of joints and cleavage planes in certain geophilous, her- 

 baceous plants. These are especially remarkable in Psoralea 

 floribunda Nutt. and Psoralea argophylla Pursh., and similar joints 

 are no doubt formed in many other such plants. 



As is well known, the American mistletoe, Phoradendron 

 flavescens (Ph.) Nutt., joroduces numerous joints, which from 

 herbarium specimens appear to develop cleavage planes and thus 

 prune off branches. The same appears to be true also to a more 

 striking extent in the European Viscum album L. The writer 

 has had no opportunity to study these plants in the field, but it is 

 probable that the whole family of Loranthaceae would afford an 

 interesting study along this line. 



It is curious that, in so recent a work as Bailey's Cyclopedia of 

 American Horticulture, no mention is made of the remarkable 

 process of self-pruning in the article on artificial pruning. The 

 subject is practically dismissed by the statements that "nature 

 prunes," and that "dying and dead branches in any neglected 

 tree-top are illustrations of this fact." But no reference is made 

 to the formation of cleavage joints and the cutting off of green 

 branches, nor the perfect manner in which the scars heal over in 

 many trees. The writer believes that horticulturists should 

 study these processes with great care, since these natural phe- 

 nomena will probably indicate fundamental principles which will 

 be well worth considering when an attempt is made to approach 

 the subject of artificial pruning in an intelligent manner. 



Ohio Tumble: Weeds — The following plants should be added 

 to the list of Ohio tumble w^eeds, as given in the Ohio Nat- 

 uralist I : 129 : 



Baptisia australis (I^. ) R. Br., perennial, frequently acts as a 

 tumble weed, although it does not seem to develop a special 

 .cleavage joint in the stem. 



.Solanum rostratum Dunal., annual, makes a good tumble weed. 



:Sisymbrium altissinunn L,., Tumbling Mustard, has been 

 reported from eastern Ohio by L,. D. Stair. — J. H. S. 



