Perhaps the most recognisable of these adaptations are the epiphytes and climbing plants. Epiphytes, plants that grow on other plants, may spend their entire life in the canopy and never touch the ground. They in turn have adaptations to capture water and nutrients such as pseudobulbs for water storage, or vase-like growth habits improving the capture of leaves. Epiphytes are often angiosperms (flowering plants), but also include ferns and lichen, both of which occur readily in cooler rainforest types such as elfin or mossy forest. Importantly, epiphytes are not parasites; they do not take any nutrients from their host plant, although, en-masse, their weight may become problematic. Interestingly, hosts may respond to this problem by excising branches, or by having particularly slippery or peeling bark.
Other climbing plants include the lianas and vines. Lianas, which are actually just woody vines, start life as saplings rooted in the ground and latch onto a host tree. Then they proceed to scramble up their host chasing light gaps, using any number of climbing mechanisms such as thorns, spikes, tendrils, and even downward facing hairs1
. Once reaching the top of the canopy they spread laterally and can make up a significant proportion of photosynthesising leaves. Lianas can be detrimental to host plants by suppressing their growth and competing for light, but at the same time have important roles in providing stability and resistance to the rainforest canopy during strong winds, as well as providing access corridors to any number of animals moving between the canopy and forest floor. Vines also climb host plants in their efforts to reach sunlight, and have leaf and stem adaptations to facilitate this, as well as to capture light in the darkest part of the rainforest where they may live for a period of time.
- Schnitzer, A. & Bongers, F. (2002) The ecology of lianas and their role in forests. Trends in Ecology & Evolution. 17 (5) 223-230.