Growth Responses Induced by Brassins (fatty plant hormones) in Bean Plants1

A single application of 10 μ g of brassins to a young internode of a ‘Pinto’ bean plant accelerated growth of the treated internode and of other internodes above and below the treated area. The treated internodes grew longer overall and thicker in some areas than comparable untreated ones. These responses involve both cell elongation and cell division. The treatment also caused marked changes in the vascular anatomy of leaves above the site of application.