Plant Growth at Iguassu by Dr. Philip Scott

Perhaps you are asking yourself... What are the students learning as they walk through Iguassu? or What is Dr. Scott pointing to in all of these photos??? Well, our traveling science professor has graciously published some of what we learned today here on the blog so that our readers can learn as well. Please enjoy the informative blog entry below written by Dr. Philip Scott.....

The 'Dos Hermanos' waterfalls we visited on the Lower Circuit on the Argentina side of Iguassu Falls provides all sorts of possibilities for plant growth. All around it, air humidity is around 100% most of the time. This can be a perfect habitat for water loving plants of course, but also for those plants living on others, be it on their trunks or upper branches, taking advantage of height to gain on light. These plants are known as epiphytes! All they need is a 'foothold' provided by their roots and they can grow way above the relatively dark tropical forest floor.

Such is the case of this set of healthy bromeliads happily growing on a falling branch close to the waterfall spray rising from Dos Hermanos. Bromeliads come in a variety of forms and sizes and are part of decoration in modern cities and shopping malls around the world. They are able to collect water between their leaves and gradually absorb it as needed in times of less rainfall. However, this characteristic provides and ideal place for mosquito larvae development. As so, they have been torn down in many tropical countries so as to diminish mosquito populations.



Begonias, also very present around waterfalls, are delicate plants living among rocks and forest litter (dead leaves, branches and decomposing organic matter present on the forest floor). Their characteristic shiny ear-shaped leaves are easily recognized. The larger size of its leaves help the plant 'collect' sunlight, by exposing more area. Their shape allows for an 'easy drip' system which gets rid of excess water present in such places as close to the waterfalls.




These small epiphytes have lens-like shapes, which 'concentrate' the suns rays, compensating for their position in shaded areas... The 'lens' is made of water stored in the leaf. Other epiphytes found during the course of our trip included delicate ferns and many types of orchids.

Another way of overcoming the general lack of sunlight in the lower levels of the tropical rainforest, is to climb/scramble to the forest canopy, as exemplified by these intertwined branches of a vine or liana. Once the vine have reached the tree tops, it will spread its leaves and develop fully. These vines can store significant quantities of water, and so be used by travelers to quench their thirst in case of need.

All of the above examples show genetic plasticity, which is Nature's way of ' moulding' life forms to adapt to different and sometimes difficult environments.