title: Phyllotaxis in xanthium shoots altered by gibberellic Acid.
abstract: Gibberellic acid treatment of vegetative Xanthium shoots induced a change in phyllotaxis and almost doubled the rate of leaf production. Phyllotaxis in control plants displayed a 2,3 contact parastichy pattern; that of the treated plants could be approximated with a 3,5 pattern. Thus, the Xanthium apex switched to a new mode of growth and a higher order of phyllotactic leaf arrangement not seen in untreated plants. It may be inferred from these experiments that gibberellic acid plays a role in determining the site of leaf initiation.
authors.forename: R
authors.initials: R
authors.lastname: Maksymowych
authors.forename: R O
authors.initials: RO
authors.lastname: Erickson