Roystonea regia, a Monocotyledonous Tree, Bears Rhizobial Root Nodules

Abstract

The first instance of a monocotyledonous tree Roystonea regia (royal palm) bearing root nodules is reported. They are formed by a Gram-negative bacterium which was tentatively identified as Rhizobium sp. The nodules are formed on younger roots of the tree mostly in the rainy season. Younger plants also become nodulated. Mature nodules are oval to cylindrical in shape, unbranched and loosely attached to the roots which show ability to fix nitrogen.