Ghosts rise from forest duff

2015-07-13 indian pipe monotropa 018Ghost plant, Monotropa uniflora, is now flowering in shaded woodlands. The species is also known as Indian pipe or corpse plant. Each stem is about finger-high and has a nodding flower at its tip. The plant’s pallor tells the story of its peculiar feeding methods. Rather than using pigments to gather sunlight, the roots are sheathed with fungi from whom the plant gets its food. Monotropa is quite specialized, connecting to a small number of Russula fungi species. The fungi in turn feed themselves by tapping the roots of trees, so Monotropa is indirectly feeding from other plants, using a fungus as the money-laundering intermediary. Whether the fungus gets anything in return from Monotropa is not known. The plant is usually regarded as wholly parasitic.

2015-07-13 indian pipe monotropa 009Monotropa belongs to the Ericaceae plant family, a group that includes heathers, blueberries, rhododendron, and sourwood. These species often live on nutrient-poor acid soil where symbiotic relationships with fungi help the plants to thrive in conditions that are otherwise hostile to roots. Monotropa also favors acidic areas and is often found in deep shade under conifers. It seems that Monotropa took its family heritage and changed it from mutualism to piracy. If so, this is the genus that no-one likes to discuss at the Ericaceae family reunion. Quite why the fungus would put up with its parasite is a mystery. It could be that the evolution of defensive mechanisms has not happened because the tiny Monotropa plant draws so little food compared to the supply that the fungus receives from trees. It is perhaps no coincidence that nearly all non-parasitic Ericaceae plants are shrubs and trees, and only Monotropa is a tiny sprout. The plant’s narrow range of fungal associates may also indicate that only a few fungus species can be fooled. All this has conservation implications: Chris Martine and Alison Hale have recently published a fascinating article suggesting that chemicals from invasive plants such as garlic mustard may disrupt the relationships between Monotropa and its fungi, causing population declines.

The species lives in North America, Asia, and Central America, with large geographic gaps between each population. Recent studies of DNA show that these populations have diverged from one another and have distinctive genetic signatures, suggesting that they might best be regarded as different species. How the species came to have such a distribution is unknown: the dust-like, winged seeds may have traveled by wind or the distribution may be an echo of the ancient geographic connections among these continents.

Five days after the bloom pictured above, pollinating bumblebees have done their work and the red fruit capsules are swelling. The flower’s rain-shedding, bee-welcoming droop has straightened and the fruit points directly to the sky, presumably the better to catch some favorable winds to a neighboring uncolonized fungus, or to Japan.

2015-07-18 monotropa fruit 002

7 thoughts on “Ghosts rise from forest duff

  1. Rosemary Stiefel

    Wonderful pictures! I am an artist living in Highlands, N.C. and paint many things found in the woods. Love your book and your Ramble things. Rosemary Stiefel. >

    Reply
  2. gary phillips

    Great post. I love your attention to detail and The Forest Unseen holds an honoured place on my shelf.
    I’d like to share a caution about the words parasite and piracy; to many of us nothing of the kind is going on. (Fit-root, my grandmother called Indian Pipe, and eye-bright.) The relationship is mycorrhizal and symbiotic; part of a positive neural network that extends to over 90% of all plant families. The Russalas are not fooled or foolish, just participating in an ancient relationship of transmission; one could even say mutual delight.
    thanks.

    Reply
    1. David George Haskell Post author

      Hi Gary, Thank you very much! I hear your words of caution and resonate with their message. My poking around in the literature has found only references to parasitism, but the literature is limited and brings a very particular lens to the world: a powerful lens, but one with limited peripheral or holistic vision. My own thinking on the network is that it is one of great (and vastly underappreciated) cooperation and, yes, delight, but is also the stage for many tensions and ruses. Out of these tensions comes yet more diversity and interconnection. I have for the last few days been puzzling of the very question you raise: if this system is “parasitic” then why do Russalas participate with such gusto? Their hyphae fully wrap the plant roots and penetrate among root cells. Methinks there is more to the story than we know, as is so often the case with fungi and the lives of plant roots.

      Your grandmother’s names are fascinating. I had heard that drops from the plant are good for the eyes, so her “eye-bright” is a wonderful name.

      Thank you very much for your thoughtful and helpful comment.

      Reply
  3. Scott

    “The Plants of Pennsylvania” (copyright 2000) classifies Monotropa in its own family, the Monotropaceae. Has the genus been recently transferred to the Ericaceae?

    Reply

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s