Mangroves can be a challenge to know. But it is a fun challenge to look at them closely and get to love their subtle differences.
For years I have been vexed by how to tell the two common Cedar Mangroves (Xylocarpus) apart and recently I decided to take a CLOSER look. Happily there was flowering material (not like that helps a lot actually).
Then I found that the two actually may have some very distinctive features even if they are not in flower.
The first feature that is used is the bark. X. granatum has smooth bark while X. moluccensis has fissured bark.
Smooth bark of X. granatum
Rough bark of X. moluccensis
The leaflets of X. granatum are thicker, and have a more tapering base, and are wider towards the tip, while X. moluccensis is thinner and has a rounder leaflet base, and somewhat ovate to eye-shaped leaflets.
X. granatum leaflet
X. moluccensis leaflet
In the individuals I looked at, X. granatum also had sort of a level or slightly depressed midrib on the upper side of the leaflets, while X. moluccensis had a slightly raised midrib.
X. granatum also has the base of the trunk extending into a plank-like buttress, while X. moluccensis has pneumatophores (breadthing roots) that stick out from the mud.
In terms of their flowers and fruits, those of X. granatum are also larger.
Another species, Xylocarpus rumphii, also occurs in Northern Queensland and I will see this in Australia sometime. This species supposedly has almost heart-shaped leaflet bases.
