Monday, June 13, 2016

Plants parasitizing Fungi parasitizing Plants - Hemitomes congestum

Sometimes our world is stranger and more wonderful than I've found in even fiction - for example, look at Hemitomes congestum.

These plants are flowering now in our yard, near the southern limit of the range of this species. That's good, because they are lovely, and because it is the only part of the plant that ever comes above ground. They don't need more of themselves exposed to the vagaries of above-ground life, as they have no chlorophyll and, unlike the vast majority of plants, do no photosynthesis at all.

With most parasitic plants (think Mistletoe or the Paintbrushes), the parasitic plant connects directly to some other, green, host plant - they tap the vascular system by imitating a branch or a root, as far as the host is concerned. That is not how this plant works.

The roots of Hemitomes are corraloid - a very strange looking affair sort of looking like a woody upside-down cauliflower. It doesn't touch or connect directly to any other plant. Instead, it pretends to be a mushroom. It does this very well, convincing the underground mycelium (the underground and largest part of the mushroom organism)  of the mushroom to give it water, nutrients, and sugars just as if it were a growing mycelium or fruiting mushroom. It is backwards - most times fungi contrive to get nutrients from the roots of plants, but in this case (and a very few others) something went weird, and the flow turned around.

The mushrooms these plants depend on are generally pilfering nutrients from plants in the forest by connecting to their roots. This is generally called mycorrhizal symbiosis, where the fungus essentially barters simple nutrients to the plant root in exchange for lipids and sugars to feed the mushroom. In many cases, this sort of life strategy is a powerful win-win, with the plants getting minerals from a larger area than their roots can cover, and the fungi getting a stable source of food.

Some of the best of the edible mushrooms live this sort of life, including the Chanterelle and the Boletes (Porcini, Butter Boletes, etc...). Few plants have figured out the trick, though. Two others in our area will be flowering soon, and I'll say something about them later. They are wild Orchids, no less!

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