Abstract
In an experimental field study of wind versus insect pollination in Baccharis spp. of Brazos County, Texas, achene production was examined under three different treatments: 1. Paper bags that allowed no pollen entry (closed condition); 2. Mesh bags that allowed only wind transported pollen to enter (mesh condition); 3. Tagged branches that were open to both wind borne pollen and insects carrying pollen (open condition). Three plants at each of two locations were subjected to each of these conditions. The unit of analysis was the individual plant, with six replications. The closed condition was used to control for the possible occurrence of apomixis. No achene formation occurred under the closed condition. Seed production under the wind only, mesh condition, varied from less than 1% to 54%. In the open condition, where insect visits were also possible, achene production ranged from 4% to 65%. The relative contributions of wind and insects to pollination were calculated for each plant. Baccharis spp. in Brazos County, Texas show evidence of amphophily-the ability to take advantage of wind or insect bome pollen, depending upon local conditions.
Griffin, Glenda Patricia (1997). Pollination in the genus Baccharis (Asteraceae): the role of wind and insects. Master's thesis, Texas A&M University. Available electronically from
https : / /hdl .handle .net /1969 .1 /ETD -TAMU -1997 -THESIS -G75.