Observations on the Nutation of Helianthus annuus

John H. Schaffner
1898 Botanical Gazette  
IN the year i890 Kellerman2 reported some observations on the nutation of the sunflower, in which he concluded that, contrary to an almost universal popular belief, the heads of Heliannthzus annuus do not turn with the sun, facing toward the east in the morning and gradually moving westward until evening. He considered the belief mainly traditional, although he found some movement through a very small space, but rarely if ever through a space approaching a half circle. He suggested, however,
more » ... gested, however, that nutation might be more marked in the head previous to anthesis. Having been a firm believer in the supposed nutation, and recalling numerous instances which seemed to support the belief, the writer desired to ascertain for himself the true facts in the case and also the conditions which may have given rise to the traditional belief. Accordingly a long series of observations were made in Clay county, Kansas, during the summers of i896 and 1897, extending in both years from June to September. The summer of I896 was especially favorable for the study, there being a more abundant and luxuriant crop of this characteristic western weed than usual. The western variety of Hel/azt/us ayinuus differs considerably in many anatomical characters from the common cultivated variety which was not included in the study. The observations of the second season were entirely a confirmation of those recorded during the first. 'Contributions from the Botanical Laboratory, Ohio State University. 11. 2Observations on the nutation of sunflowers. Trans. Kan. Acad. Sci. I2: I40-T iX 8In0-Qn0. 1898] 395
doi:10.1086/327699 fatcat:kj7mjxyuefevfbdfaexrtqs5ma