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Trunks and Stems

Given the high level of precipitation in rainforest habitats, soil is inclined to erosion, which can lead to the toppling of vegetation. To increase stability, many rainforest trees have trunks that widen significantly at the base, in a wavy mass of ribbons that may stretch many metres away from the trunk and stand several metres high. This particular type of trunk base called a buttress, has a significantly larger surface area about its base increasing the stability of the plant in the soil. An alternative to this is to produce a stilled or prop root system, in which secondary roots grow obliquity from the main bole toward the ground, much like a witches’ broom.  Again, this increases the amount of contact between the plant and the ground, increasing the stability of the plant and the soil.

Buttress roots provide extra stability in the rainforest - Zoe-Joy Newby

Massive buttress roots provide stability to this rainforest tree - Zoe-Joy Newby

Stilt roots seen frequently on vegetation at Lord Howe Island - Leahwyn Seed

A stilt root system developing on a Pandanas tree - Zoe-Joy Newby

Buttress roots on Spurwood Dysoxylum pettigrewianum in lowland tropical rainforest - Rob Kooyman

Buttress roots on Yellow Carabeen Sloanea woolsii in lowland tropical rainforest (Nightcap National Park) - Rob Kooyman