Re: folliw up to long roots and stems

Mick Nally <mick at roch-inst_co.uk> wrote, Friday, 12 Apr, 1996: (parts snipped)

>> It sounds like you have good growing conditions for your plants and the
>> swords are a variety that is just too big for your tank.  They may also be
>> a variety that likes to grow emersed.
>Quite possibly, but I also thought it might be an effect caused by not enough
>light. (?)
In general, plants do get longer petioles on their leaves and develop
thinner , but not necessarily larger leaves in response to less light.
Swords under low light conditions, however, are likely to continue
producing underwater leaves, whereas, in good light, some species develop
aerial leaves, which usually have a different shape than the underwater
leaves. One of my books recommends cutting off the big aerial leaves to
'discourage' the plant and make it start producing underwater leaves.
Since plants don't have nervous systems, I assume that the nature of the
discouragement is a general injury type of setback that reduces the size
and vigor of the plant, causing it to make underwater leaves.  In other
words, you gotta keep the swords small to keep them from growing aerial

>> No doubt your Anubias plant that was under the swords needed more light.
>> That is an impressive length of root, but you will probably find, if you
>> were to dig up any of the three plants that have been getting better light,
>> that they had as long or even longer roots.  Possibly your poorly lit
>> rhizome grew those long roots when it was better lit (before the swords got
>> so big) and when it had more leaves.

>I was wondering if this could also be a low lighting effect and the plant
>was diverting its resources into root production rather than leaf production.
>Does anyone know if exagerated root development is related to poor lighting?
>Having said that, I do have 2 Watts/(US)Gal which with plain gravel and no
>CO2 is probably OK; as Paul noted this plant was in a localised area of shade
>due to the monster swords.
I have never seen, in my reading about plants, that they might respond to
low light by growing longer or bigger roots.  It would seem to be
counterproductive for a plant to do such a thing, when it should be putting
its resources into making as much leaf area as possible to intercept as
much light as possible and to get the leaves as near as possible to the
source of light.  In general, plants grow larger and more vigorous root
systems in better light.

Paul Krombholz                  Tougaloo College, Tougaloo, MS  39174