Re: Why do roots exist?
The roots of aquatic plants are fully functional!!! Anyone who baldly
states that they are merely for anchoring the plant underwater has a
complete lack of understanding of basic aquatic plant physiology AND
SHOULD BE IGNORED COMPLETELY!
The reality is that rooted aquatic plants acquire the majority of their P
from the sediment via their roots. The same goes for nitrogen. The reason
is that N and P in natural systems are at a much greater concentration in
the sediment than in the water. In addition, aquatic sediments are
anaerobic which means that N and P are either in a more useable form
(NH3-N) or solubilized and more available. The anaerobic sediment also
reduces ferric iron, which is insoluble, to ferrous iron which is soluble
and much more available for plant uptake.
There is also evidence which indicates the presence of a 'transpiration'
stream in aquatic plants. This means that aquatic plant roots absorb
water and can push it up into the foliage, thereby delivering nutrients
to the upper parts of the plants.
Over the past century there have been a plethora of controlled,
repeatable experiments carried out by reputable scientists which clearly
show that aquatic plants grow better on a fertile substrate. In addition,
recent studies have indicated, as mentioned above, that N,P and perhaps
most other nutrients, can be supplied exclusively from the sediment via
the roots (references upon request). Only Ca, Mg and K have been shown to
be essential in the water column. Interestingly, there are even some
aquatic plants which acquire the majority of their CO2 from the sediment!
So, the next time somebody tells you roots are non-functional, just walk
away because they just dont know what theyre talking about.