Knee Roots

One of the most fascinating aspects of a visit to a swamp are these plant formations called "knee roots." They seem to grow in a number of different types of trees. Here is a description of Cypress knees:

A cypress knee is a distinctive structure forming above the roots of a cypress tree of any of various species of the subfamily Taxodioideae. Their function is unknown, but they are generally seen on trees growing in swamps. Some scientists have thought they may help in oxygenation to the tree's roots or assist in anchoring the tree in the soft, muddy soil.

Technically, they are called pneumatophores. Here is a further description of their development. 

Pneumatophores are erect roots that are some form of upward appendage or extension of the underground root system. Because these roots are exposed at least part of the day and not submerged underwater, the root system can obtain oxygen in an otherwise anaerobic substrate.

This particular article, entitled, "Guide to the Mangroves of Singapore, How Plants Cope in the Mangroves, further explains:

In Bruguiera and Ceriops the horizontal roots growing just below the soil surface periodically grow vertically upwards then immediately loop downwards to resemble a bent knee. By repetition, a single horizontal root develops a series of knees at regular intervals. 

The aerial portions (knees) of these roots help in aeration of the whole root which because it spreads so widely, improves anchorage in the unstable mud.

I have always been impressed with the adaptation of plants to the dry deserts of the world, I guess I am learning about areas that have a little more water.