Black mangrove (Avicennia germinans)
Figura 17. Black mangrove ecosystem in La Parguera, Lajas, Puerto Rico.
The black mangrove (Figure 17) tends to be located behind the red mangrove, in sal er and less aerated soils. This species tolerates more strenuous climate condi ons and is associated with poor soils or soils with high salinity.
Main characteris cs: Leaves: The black mangrove’s leaves are smaller than the red mangrove’s, and are lanceolate, with a sharp point at the apex (Figure 18). The dorsal surface (the top side of the leaf) is green, while the ventral surface (the bo om side of the leaf) is yellowish green and opaque (Figure 19). Black mangrove leaves are opposite (begin at the same point on the branch, but in opposite direc ons) and serve as the tree’s salt excretory organs (Figure 18). The salt crystals are deposited on the dorsal surface through stoma. This process ensures that the tree maintains the necessary water it needs for its survival. Older leaves tend to accumulate higher concentra ons of salt before falling off and showing burn spots due to the “magnifying glass” effect created when sunlight is filtered through the salt crystals.
Figure 18. The dorsal side of a black mangrove leaf, presen ng salt crystals.
Figure 19. Ventral (bo om) leaf surface.
The Mangrove Forest: Student Handbook
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