Morphology of four root types and anatomy of root-root junction in relation gas pathway of Avicennia Marina (Forsk) Vierh roots

Avicennia marina plants not only survive in a stressful intertidal and anaerobic environment, but also continue to shoot and root growth, flowering, and fruiting despite the unfavorable conditions of the oxygen-depleted soil. Internal root aeration is an effective adaptation mechanism that maintains oxygen transport to support growth and development. In the present study, internal root anatomy was investigated in four root types of A. marina by using light and scanning electron microscope to analyze structures, shape, extent of cell and tissue that compiled the roots. This species had four root types, i.e., cable roots, pneumatophores, feeding roots and anchor roots. In the junction area of all root types, there is a transition area of aerenchyma in the region between cortical tissue with longitudinal oriented cylindrical channels and a little loose spongy tissue with no apparent direction of orientation. This area supports the continuation of gas space between the cylindrical channels of one root type to the others by intercellular space on the tissue of this mass tissue.