Explanation:

 Buttresses are a feature of many trees in all tropical rainforests. They are woody flanged extensions that radiate outwards from the lower part of the tree trunk and often reach large proportions. Most rainforest soil is very poor with all the nutrients available largely remaining at surface level. Because of this rainforest trees have very shallow roots. Some very tall trees have developed ways of obtaining much needed additional support by forming buttressed roots, which grow out from the base of the trunk sometimes as high as 15 ft above the ground. These extended roots also increase the area over which nutrients can be absorbed from the soil.