The Carnivorous Plant FAQ Field Trip Report -

Eastern Oregon carnivores in 2006

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I am fascinated by the purplish-black color that is sometimes seen in Utricularia bladders. Under a microscope it is possible to see how the dark pigment is produced in the tissue of the bladder walls. Sometimes the coloration is red, sometimes purple, sometimes black, and the difference in color is presumably primarily an issue of concentration. I frequently read accounts of Utricularia which say the bladders may blacken because they are filled with prey. I think these accounts are misinterpretations of the pigmentation.

Why do these plant do this? And why is it the case that in some habitats, Utricularia bladders of the same species are not purplish at all?

Incidentally, I also found U. minor plants growing in the same particularly leech-festooned waters, although I do not have any photographs of them.

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Revised: October 2007
©Barry Rice, 2005