One of the popular features along the Rich Lake Trail is our glacial erratic, an enormous boulder left behind by the glaciers over 10,000 years ago. Kids love it because it is huge and easily accessible. Adults love it because it is huge and impressive. Naturalists love it because it is covered with wonderful plant communities, each occupying a niche that meets its specialized needs.

For example, on the western face of the rock there are assorted mosses and liverworts. On the top of the rock, looking rather like a crewcut, is a healthy population of polypody ferns and even a small balsam fir seedling. But along the shady eastern face, ah, one encounters these crazy flat, flappy growths of significant size: rock tripe.

Rock tripe are a kind of lichen, and there are many species of rock tripe around the world. The species that graces our glacial erratic is Umbilicaria mammulata, the smooth rock tripe. Probably the most common rock tripe in the northeast, it can reach diameters upwards of 30 cm – this is a lichen of some significance.

Let’s start our investigation of smooth rock tripe with a look at the name. According to most sources, the English name “rock tripe” comes to us via France, where it is called tripe de roche, literally “rock guts.” I am not a speaker of the French language, but even I can deduce that roche is rock, which means tripe must translate as gut. Some further digging proved me right, for “tripe” is the word used to describe the tissue from the stomach of a ruminant animal (a cow, for example), which is used for food (mmmmm). I grew up with the phrase “tougher than tripe” peppering the family’s lexicon, so I can only imagine that eating real tripe is an exercise in developing the muscles of the jaw. This does not bode well for the edibility of this lichen.

Yet, it turns out that rock tripe is indeed edible. Of course, the palatability no doubt depends on the species in question. For example, in many Asian countries, rock tripe is considered a delicacy and is much sought by connoisseurs. On the other hand, the Inuit consider rock tripe to be a starvation food, eaten only as a last resort. The Cree, however, ate rock tripe as a regular part of the diet, often using it as a thickener for fish broth. Each of these peoples is eating a different species, which one should keep in mind if one is deciding to give rock tripe a try.

Reading through the history of the use of this lichen, I’ve come to the conclusion that the description of the Inuit’s rock tripe best fits smooth rock tripe – a starvation food that you’ve got to be pretty desperate to eat. George Washington’s men filled their bellies with it at Valley Forge in the winter of ’77 – they lived, but didn’t thrive. This could be in part because the lichen can act as a purgative. Or it could be because it’s not terribly nutritious – it will fill you up, but your body won’t get much from it.

Eating rock tripe is not something to be undertaken lightly. For one thing, it is full of bitter compounds and therefore must be soaked and boiled in several washes of water to render it edible. What is often left is this rather slimy mass. Good for thickening broths. It can be roasted, or fried. Personally, I think I’d have to be pretty darn hungry to give it a try.

Let’s revisit the name once more, this time looking at the genus, Umbilicaria. If it looks familiar, it should – think of umbilical cord. See the similarity? Both are derived from the Latin word umbilicus, which means navel – the point at which the umbilical cord attaches. If one takes a close look at rock tripe, one sees that it has a navel, too – right about at its center. It is from this navel that the lichen attaches itself to its rocky home.

I love visiting our rock tripe colony at various times throughout the year, because as the weather changes, so does this lichen. When times are good and there is plenty of moisture, the lichen is soft and pliable, like a piece of good leather. In times of drought, it becomes quite brittle, shriveling up a bit and prone to damage. When it’s in this brittle state, it is somewhat less impressive to the casual visitor, but even so, it is worth checking out.

If you are checking it out on our glacial erratic, please do not pull it off the rock, for, like all plants and animals at the VIC, it is protected. But once you know what it looks like, you can head out and look for rock tripe on the rocks on your own property. And if you decide to sample it, stop on in and let me know what you thought – starvation food or culinary delight.