Jan., 1905.] 
Plants with Nodding Tips. 
267 
PLANTS WITH NODDING TIPS. 
John H. Schaffner. 
In the plant kingdom are to be found many peculiar adapta- 
tions. One of the most interesting is the habit which some 
species have of keeping the growing tip curved downward during 
the period of development or until the stem has attained its 
growth for the season. This 
curving of the tip of the stem 
appears much like the arch 
commonly developed in 
sprouting seedlings but must 
be for a different purpose. 
The nodding of the grow- 
ing tip is strikingly seen in 
such plants as Solidgo can- 
adensis (Fig. 1) and Asimina 
triloba. Some species of a 
genus may nod while others 
show no sign of a curve in 
the stem tip. Thus Gaura 
parviflora nods very strongly 
while Gaura biennis, it ap- 
pears, does not nod at all. In 
most cases the curve is quite 
rigid but in some the nodding 
is merely the result of the 
flexibility of the stem. A 
ding^'^s^’ few species have the tips nod 
at night but become nearly 
straight in the daytime. Whatever the cause or factor which 
induces plants to nod, there is probably no doubt but that the 
habit is a means of protection to the delicate terminal bud. 
Species with Rigid Nodding Tips. 
Salix cordata Muhl. Vitis vulpina L. 
Ulmus americana L. Ampelopsis cordata Mx. 
Ulmus fulva Mx. Parthenocissus tricuspidata(S.& Z.)P1. 
Asimina triloba (L.) Dun. Gaura parviflora Dougl. 
Albizzia julibrissin Boiv. Solidago canadensis L. 
Vitis labrusca L. Erigeron philadelphicus L. 
Species with Flexible Tips. 
Tsuga canadensis (L ) Carr. Juniperus communis L. 
Species with Tips which Nod at Night. 
Cassia chamaecrista L. Euphorbia nutans Lag. 
