I've never once seen this occur in nay planted tank, with 300 plus species grown to a high level, I think I'd seen it if it was really real and wide spread...........
Terrestrial plants it has been shown, it's never once been shown to occur in any natural aquatic system to date.
And that's the real test and thing folks need to address.
All the talk Diana does is nice speculation, but it's very easy to disprove and test for in aquariums as well as look up research that is applicable to the real world in aquariums.
Ground extract of plants at high concentrations is hardly like the situations we have in our aquariums.
A very simple test to disprove that allelopathy in algae or plant-plant interactions: add some Activated carbon and change every week or two.
You should not see any effect when you add the AC, if you think allelopathy controls algae, then adding AC should cause an algal bloom, but we have never once seen this, so I have to conclude based on the research that's applied, as well as relative simple experiments any aquarist can do, that this does not occur.
You can speculate, but the book offered nothing that shows it does in fact occur in our tanks with live living plants no matter what anyone might want to say about it.
Information is not knowledge.........
Regards,
Tom Barr