Date of this Version
Published in Transactions of the Nebraska Academy of Sciences, Volume 2 (1973).
Vernonia gigantea (Walt.) Trel. ssp. gigantea is distributed throughout the Eastern United States. It ranges from eastern Texas to northern Florida and northward to southeastern Nebraska and southern New York. Vernonia gigantea ssp. gixantea exhibits weak correlation with a latitudinal gradient. Reciprocal transplant experiments were carried out using cloned pairs of plants from different areas of the taxon's range to determine if this correlation is due to genetic differences or to environmental factors. Differences in flowering response between northern and southern populations were noted in the garden transplants. An experimental crossing program was carried out among individuals from different localities in order to determine whether reproductive isolating mechanisms existed among populations.