Re: Allelochemicals, roots and competition

Subject: Allelochemicals, roots and competition
> > From: krandall at world_std.com (Karen A Randall)
> > > Yet A. mad. will
> > > continue to show very slow growth even with trimming back th
> > > neighbours. 
> > 
> > I'm not at all sure that what you are seeing in this case is 
> > competition.
> OK, but competition is a good possibility tho? What other 
> possibilities are you thinking of?

A. madagascariensis is such a difficult plant that there are too 
many possibilities to guess at.  The growth pattern you describe 
is pretty typical of what it does when it's not happy.

I've heard lots of stories of people having long term success with 
ONE mad. lace plant.  I have yet to hear of anyone who was 
CONSISTENTLY able to keep them going.  I know of a Kmart that had 
one that grew so large for so long, in colored gravel, no 
fertilizer, over head (not on the tank) cool white lighting, that 
they were able to divide it regularly and sell pieces.  The point 
is, however, they were never able to repeat their success with 
another plant.  When I meet someone who has had _repeatable_ and 
sustainable results, I will want to examine there methods very 

I admire you in your persistence, and wish you the best of luck.  
But I think it's too soon to decide what's working and what isn't. 
 There are just too many variables.  

> > I agree with you completely here.  In fact, I have read severa
> > reports of success where the plants were kept either as a sing
> > specimen, completely by itself, or else in a monoculture.
> And to me this suggests that the plant does not fare well in
> a competitive situation. I don't think it's light that is the
> limiting factor and it may have something to do with the other
> plants which are present or in my situation, it may be that 
> the plant doesn't recover well after being moved or disturbed.
> Anyone who has had "success" with the lace plant either alone
> or in combination with other plants in crowded or uncrowded
> situations could please comment further.

I point back to my previous comments.  I have heard of people 
having very good luck with _a single specimen_ over long periods 
of time.  So far, I haven't heard of anyone being able to repeat 
the experience on more than a completely random basis.  I wish 
this were not the case, and I hope you have the time (and the 
$$<g>) to stick with the project long enough to figure it out.  
Just make sure you don't jump to conclusions. ;-)

> I'd like to pick this up again with Charley's next comments
> where he makes some interesting points.

> > John's comments may be correct as far as they go, but dismiss 
> > fact that _many_ of the plants we use in the aquarium are 
> > (completely or in part) _not_ root feeders, and their needs mu
> > be met as well. 
> Yes, but John was talking about rooted plants. ;-)

John was responding (if I remember correctly) to a post about 
aquarium plants and fertilization in general.  I'm sure there are 
some aquarists who keep only root feeding plants, but I don't know 
> Substrate fertilization might be worth considering as a 
> method of limiting nutrients available to algae and some 
> of the fast growing water feeders. Also, unlike in nature, 
> in a tank we have high concentrations of nutrients in 
> the water whereas in nature these tend to be available only
> at the roots especially the micro-nutrients. As well,
> nutrients in the substrate will also tend to go into the
> water solution with time and there should be no shortage of
> nitrogen or phosphates since these originate from the food
> and fish wastes. It also might be interesting to see how
> it would work in a plant only tank!

I actually have trouble keeping viable colonies of floating plants 
going in my tanks. (Duckweed, Salvinia, Riccia etc.)  But I have 
no measurable nitrate or phosphate either.  Even Water Sprite I 
have to watch closely.  If it starts to lighten up, I know that I 
am not dosing heavily enough with trace elements.

I don't know many people who fertilize with phosphate or nitrogen, 
so I assume (perhaps wrongly) that John was talking about micro 
nutrient supplementation.  I wouldn't purposely add nitrogen or 
phosphate to the substrate either.



Subject: Allelochemicals, roots and competition

> > From: Charley Bay <charleyb at hpgrla_gr.hp.com>

> > Getting back to the "first day", some individuals *can* releas
> > while others (if they exist at a very low NPP for a significan
> > portion of their lives) will never release even though an 
> > infinite amount of space, light, water, and nutrients are 
> > available.
> Sounds like A. mad.
> > However, most plants are "capitalists", and perform the curren
> > year's mitosis and cell expansion completely dependant on the 
> > year's nutrient availability.  They can best take advantage o
> > (capitalize on) nutrient availability, but can be very stresse
> > a "false start" on nutrient supply for the year falls short of
> > plant's later needs for completion of the cell expansion proce
> Upon first putting a new bulb into a tank, it grows like crazy
> putting out big new leaves. I think these leaves are the ones
> that the plant needs to have functioning for its photosynthesis
> factory to produce and store food reserves, or to continue growi
> If at this stage, you practice pruning and there is a sufficien
> supply of nutrients, I think it would keep on sending up new lea
> If, however, you move it (as I have done) I think you disrupt
> the roots too much and the plant just doesn't recover. It just
> doesn't have that second wind that even in a new environment
> with plenty of nutrients and light, it doesn't seem to "release"
> It could be that it would release, if there wasn't allelochemica
> or root competition preventing that. From what you say, however
> I suspect it's just that the plant is one of those which does no
> recover well from a change in the environment which might allow
> it to continue new rapid growth.

I like this hypothesis much better.  I would explain why so many 
of these plants are unsuccessful no matter _what_ is done with 
them.  It could even be that _when_ they are collected is critical 
to their long term survival.

Karen Randall
Aquatic Gardeners Assoc.
Boston, MA