Trees with Straws:
Black Mangroves
The Black mangrove’s real name is Avicennia germinans. Just like other mangrove trees, they also provide a home for fish, birds and other wildlife as well as protect the coast and the coral reefs. The Black mangrove got its name because of the colour of its wood, dark brown to nearly black. The wood is heavy, strong and hard and is used in some countries in construction or for charcoal and fuel. The bark of the Black mangrove has tannin, a substance used to tan leather products.

Black mangroves grow in muddy or sandy soils further inland than the Red mangrove. Ground that is always wet does not have much oxygen in it. The roots of land plants need oxygen to help the plant grow. If the roots can’t get enough oxygen, the whole pant dies. But Black mangrove has special parts that help them to live in the marshland. They have unique roots called pneumatophores. These roots are aerial roots that stick up from the ground like drinking straws. They help bring extra oxygen to the tree. If the pneumatophores are flooded by water for too long or buried under sediment, the mangrove will not get oxygen and die. Oil pollution also kills mangroves when the oil sticks to the pneumatophores and stops the plant from getting oxygen.

Black mangroves also produce seeds with mangrove saplings. They are not pencil-shaped like the propagules of the Red mangrove. Instead, they are small and oval. But they can also float for long periods before the sapling roots.

The Black mangrove has narrow, egg-shaped shaped leaves with pointy ends. Although the leaves are dark green, they are often whitish. This is the salt that the tree pushes out its system. All living things on our planet need fresh water to survive. Mangrove trees have adapted to their salty environment by being able to turn salt water into fresh water and pushing out the salt through the pores in their leaves.

CONTINUED: The White Mangrove »