The effect of gibberellic acid on the germination, growth and development of Trifolium repens L

1. Gibberellic acid had no effect on the germination of six species of small-seeded legumes. 2. Seven varieties of Trifolium repens L. plants were treated with gibberellic acid and their responses determined. All varieties showed an increase in petiole length and individual leaf area due to an increase in cell numbers; a decrease in stolon numbers and length was also noted. The total leaf area per plant remained unchanged. Total dry weight, shoot dry weight and root dry weight were each significantly reduced. 3. The stolons lost their normal diageotropic response and became negatively geotropic and it is postulated that the stoloniferous habit may be due to a gibberellic acid/indole-acetic acid interaction. 4. Because treated plants of Wild white clover closely resembled untreated plants of Ladino clover it is postulated that endogenous levels of gibberellins may play an important part in the development of varieties and in the evolutionary process as a whole.