Autumnal Daylight Weather and Camphor-Weed Dispersal in the Georgia Piedmont Region

Abstract

1. The advancement into new areas by Heterotheca latifolia throughout much of the Georgia Piedmont coincides generally with the combined velocities of all the winds along the directions of the prevailing wind patterns. Camphor-weed does not occur in the mountains partly because the winds have not carried it there as rapidly as winds have moved it into the south and southeast. 2. Within the habitat the achenes generally fall within 30 m. of the parent plant, and most of them fall within 15 m. Wind gusts greater than 12-14 miles per hour and turbulent updrafts carry some seeds aloft, however. Dissemination occurs best on clear days that are abnormally windy and dry, that is, with winds of more than 12 miles per hour and a VPD greater than 10 mm. Hg. 3. The daytime weather at Athens, Georgia, and Spartanburg, South Carolina, is quite similar, except for the direction of the wind patterns. Specific weather data associated with seed dispersal have been summarized for this autumnal season. Early afternoon weath...