BRIEFER ARTICLES 
THE NUTATION OF HELIANTHUS.’ 
In a former contribution? the writer presented the results of 
extended observations on the nutation of the wild variety of He/an- 
thus annuus. Considerable subsequent study in the same direction 
has fully confirmed the statements 
made at that time. It was, how- 
ever, impossible to present satis- 
factory illustrations of the plants 
in the field, no camera being at 
hand when the observations were 
made. Since there seems to be 
some skepticism as to the fact of 
nutation, it was thought desirable 
to add a few more recent studies 
and some photographs showing 
the actual appearance of the plants 
in the field. 
During the summer of 1898 a 
series of observations was made 
in Columbus, O., on the common 
cultivated variety. The cultivated 
Sunflower behaves very much like _ Fic. 1.—Cultivated Helianthus annuus 
the wild one, except perhaps that at 6 P.M, three plants showing the sone 
it appears somewhat less striking W@td nutation, one 
in its reactions. The growing dees? gts es 
Plants nutate from 60° to go° west in the evening (figs. 1,2), and 
om 50° to 70° or more, east in the morning (fg. 3). At night 
the leaves droop and the tips point downward. : 
When anthesis begins nutation ceases and the heads are tilted 
toward the east or northeast (fig. g). Not only the main terminal 
heads but also some of those on the side branches take this position. 
VII. 
*Contributions from the Botanical Laboratory, Ohio State University. 
* Observations on the nutation of Helianthus annuus. Bot. GAZ. 25 + 395-403: 
197 
