III Inundated by higher than normal tides: Most of Rhizophora species

IV Inundated by spring tides:

V Occasionally inundated by exceptional equinoctial spring tides: Bruguiera

Tomlinson (1986) limited mangroves (N.B. Mangal was used in the text instead of mangrove) into 3 groups, viz.:

I Major Mangrove elements

II Minor Mangrove elements

III Associated Mangrove elements

A fairly rigid criteria to distinguish mangroves was used. Mangrove elements are recognized because they possess all or most of the following features:

1. Complete fidelity to the mangrove environment; that is, they occur only in mangal and do not extent into terrestial communities.

2. A major role in the structure of the community and the ability to form pure stands.

3. Morphological specialization that adapts them to their environment; the most obvious are aerial roots, associated with gas exchange, and vivipary or viviparity of the embryo.

4. Some physiological mechanism for salt exclusion so that they can grow in seawater; they frequently visibly excrete salt.

5. Taxonomic isolation from terrestial relatives. Strict mangroves are separated from their relatives at least at the generic level and often at the subfamily or family level. For minor mangroves, the isolation is mostly at the generic level.

The minor elements of the mangal are distinguished by their inability to form a conspicuous element of the vegetation. They may occupy peripheral habitats and only rarely form pure communities.