Does purple indicate oxalic acid in plants?

Because rhubarb stems contain a lot of oxalic acid, and they’re purple. And clover roots are also purple, and develop purple specks in the leaves as they age and their oxalic acid content increases. And dandelions are the same, but not oxalis plants as far as I can tell… though they do have purple root bulbs…

Disclaimers:

  1. Yes, I know they don’t contain oxalic acid as such, but oxalates.
  2. Yes, I know there are other reasons a plant might be purple.

I dunno why this popped into my head, but is there a correlation?

Oxalis not purple ? Or did I misunderstand ?

Ah… right. The kind we get here is yellow with green leaves.

I think it’s this kind, but if not it at least looks like it. I didn’t know they came with different coloured leaves but it only adds to my hunch.

Oxalates are found in rhubarb leaves not so much the stem.

Anthocyanins, are the major purple pigments in plants. Most oxalic acid salts are white.

Interesting question. In plants where purple is not a normal color, purple stems/petioles can be a sign of phosphorus deficiency. I am not sure if this means anything in relation to the OP, but hey.

Hmm… Poke is another semitoxic plant with great purple stems and oxalic acid. Beets have oxalic acid.

But so do cabbage, potatoes and peas.

Pokeberry’s got other toxins as well:

The Aubergine that ate Rangoon, does not appear to contain significant Oxalic Acids according to my quick web search.
But the very green Spinach does as does

from http://www.answers.com/topic/oxalic-acid