Nov., 1904.] 
Twigs of the Common Hackberry. 
215 
A number of nutating plants have been studied by the writer 
in the past and during the present year observations were con- 
tinued on various species which it was thought might show the 
peculiarty. The following six species show a movement of the 
stem tip and terminal leaves when conditions are favorable. 
Chenopodium album L. 
Polygonum lapathifolium L. 
Polygonum pennsylvanicum L. 
Euphorbia hexagona Nutt. 
Euphorbia dentata Mx. 
Iva ciliata Willd. 
The two Euphorbias have a very decided nutation, the curva- 
ture of the stem often being as great as in the Sunflower. 
TWIGS OF THE COMMON HACKBERRY. 
John H. Schaffner. 
Our blackberries demand careful study in the field in order 
that some of the obscurities may be removed which now appear 
in the descriptions of our Manuals. Celtis occidentalis L. is said 
to have “glabrous twigs” and “leaves smooth above.” Celtis 
crassifolia Lam. is said to have “the young shoots puberulent” 
and “leaves scabrous above.” Now, we can find all of these 
characters on different twigs of the same tree. 
So far as Celtis occidentalis is concerned, I have not found a 
Hackberry in Ohio or Kansas that did not have pubescent twigs. 
The tree has two types of twigs; fruiting twigs and twigs which 
bear no flowers. The fruiting twigs have a few scattered hairs 
when young but these usually fall off early. The leaves are very 
glabrous above and of a peculiar appearance. These fruiting 
twigs dry off at the outer ends while the fruit ripens and they are 
then very abundantly detached, a brittle layer being developed 
at the base. Often the twigs come down with the drupes still 
attached. The purely vegetative shoots are usually quite pube- 
scent when young, the pubescence extending to the leaves. In 
most cases the pubescence is persistent on the twigs and the 
mature leaves are quite scabrous or hairy. As one goes west- 
ward the pubescence of the vegetative shoots appears to become 
more pronounced, and one can find trees with very smooth 
fruiting twigs and very hairy vegetative twigs. 
Are there any characters to establish the species, Celtis cras- 
sifolia Lam.? From an examination of supposed C. crassifolia 
and C. occidentalis identified by competent botanists I can find 
no specimens in either set which cannot be duplicated by twigs 
