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Diurnal Patterns of Pollen Emission in Ambrosia, Phleum, Zea, and Ricinus

Eugene C. Ogden and Janet V. Hayes
American Journal of Botany
Vol. 56, No. 1 (Jan., 1969), pp. 16-21
Stable URL: http://www.jstor.org/stable/2440389
Page Count: 6
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Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
Diurnal Patterns of Pollen Emission in Ambrosia, Phleum, Zea, and Ricinus
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Abstract

Hourly measu rements of pollen emission were made from cultivated plots of Ambrosia, Phleum, Zea, and Ricinus over the course of several pollination seasons as part of a study of pollen dispersion from known sources. A characteristic diurnal emission pattern was found for each genus Ambrosia pollen emission normally begins an hour or two after sunrise, peaks a few hours later, and decreases through the afternoon. Phleum starts during the night, peaks about 2 hr after sunrise, and declines slowly through the day. Zea emits pollen fairly uniformly during the period from 2 hr after sunrise to about sunset, while Ricinus pollen was collected from several hours after sunrise to late afternoon with a peak in mid-morning. Daily patterns often vary from the seasonal mean in response to changing meteorological conditions.

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