Ask Sam: How is this SpoOOoOoky Plant Feeding Itself? | New Hampshire Public Radio

Ask Sam: How is this SpoOOoOoky Plant Feeding Itself?

Oct 30, 2020

SpoooOoOOOky!
Credit Flickr Creative Commons | liz west

Sam Evans-Brown is the host of NHPR's Outside/In podcast and radio show. Do you have a question for Sam? Call 1-844-GO-OTTER or email outsidein@nhpr.org.

Sarah from Andover, New Hampshire, asks:

I have a question about a very spooky plant the ghost plant, Monotropa uniflora. I teach high school biology and typically we teach plants as being autotrophs, as in they take sunlight and convert it to sugar. However, our ghost plant here in New Hampshire does not have chlorophyll, which means it’s not photosynthetic and it’s stealing its energy and nutrients from its host tree. So are ghost plants considered an autotroph? Or a heterotroph?

Ok, ok, ok, so that’s a little biology vocab 101: autotrophs make their own food, heterotrophs eat stuff. You’re a heterotroph, your dog is a heterotroph, that mold on the sour cream in the fridge is a heterotroph, but your houseplants are autotrophs. 

It’s very possible that you’ve seen the ghost plant, or ghost pipe, or corpse plant or indian pipe (all names for the same thing) in the woods and not even realized you were seeing a plant. I have seen them on plenty of walks, and had guessed it was a weird mushroom. 

But it’s not.

I took this question of the ghost pipe to the senior research botanist of the Native Plant Trust, Arthur Haines. He was unequivocal. 

“It’s a heterotroph,” he said, “and we could further classify it as a myco-heterotroph. In this case they’re deriving their nourishment from fungi that are mycorrhizal on the roots of trees.”

So this spoooooky plant is actually more like a vampire: it’s a parasite. It’s stealing nutrients from the networks of underground fungi that have co-evolved with trees. 

They lost their chlorophyll because over time as they got better and better at stealing nutrients from fungus, because evolution started selecting for ghost plants that were more and more corpse-y, since chlorophyll is energy-intensive to produce.

Now, this gets to something that has been described as a kind of science party trick by Radiolab's Lulu Miller. In her new book, Why Fish Don’t Exist, she points out that any definition of fish that you choose will have exceptions. There are creatures like the lungfish, which is actually more closely related to four-legged animals than other fish. 

Similarly if you were to google the definition of plant, almost every one of the simple definitions you find say: plants are things that use photosynthesis to make their own food. 

But clearly, this is a plant.

“It’s a flowering plant, it has an ovary, it produces a fruit, it has leaves stems, roots… it has literally everything that most, if not all plants have,” says Haines, “When we look at the full diversity of the plant kingdom, we can’t use possession of chlorophyll as a meaningful way to describe all plants.”

Maybe this is a stretch, but perhaps we can use this very spooky plant as a way to discuss how sometimes our definitions are generally too restrictive, and don’t allow us to see the true diversity that exists in all living things?

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