Dec., 1903 .] 
Notes on Nutation of Plants. 
usually uot more than 2o°-3o° east. During dr}- weather the 
amount of nutation was increased b}" watering the plants. As in 
the sunflower, the stem is usually straight by lo o’clock at night. 
Ambrosia artemisaefolia was studied and found to nutate well, 
as reported by Stevens. Ambrosia psylostachya and Xanthium 
speciosura also nutate, considerable movement of the stem being 
readil}- observed during favorable conditions. Helianthus maxi- 
miliani, H. grosseserratus, H. hirsutus, and H. tubersus nutate 
well before anthesis. H. maximiliani is especiall}^ striking on 
Fig. I. Helianthus annuus nutating to the west at 7 p. m. 
Fig. 2. Ambrosia trifida at 7 p. m. Both from Clay Co., Kansas. 
occount of its stout stem and slender, rigid leaves. On favorable 
dat's the nutation is 90° west in the evening and 20° or more east 
in the morning. 
Although Stevens gives Amaranthus as a genus which shows 
nutation, he does not name the species observed. During the 
past summer two species were studied by the writer, namely, 
Amaranthus hybridus and A. retroflexus. The first nutates the 
more prominently both in the morning and evening, probably be- 
cause of its more slender stem. The process is much the same as 
in the sunflowers, but the curve in the stem is not nearly so 
abrupt. However, on favorable evenings the terminal rosette 
faces the setting sun to such an extent that the rays of light fall 
on the broad surface of the leaves at right angles. 
