title: The pattern of development of Anabaena in the Azolla-Anabaena symbiosis.
abstract: The development of Anabaena in the leaf cavities of Azolla (probably A. filiculoides) was studied. After the alga is installed in the cavity, heterocyst frequency rises to a maximum (20-30%) about 12 leaves from the apex, then remains constant until the leaf senesces. The size of vegetative cells of the alga increases with cell width apparently increasing linearly with increasing leaf age.
authors.affiliation: Department of Plant Biology, University of Newcastle upon Tyne, Ridley Building, NE1 7RU, Newcastle upon Tyne, U.K..
authors.forename: D J
authors.initials: DJ
authors.lastname: Hill