According to the ancient Doctrine of Signatures, like heals like.  

What if those historic healers were correct in that assumption, and natural objects could serve as medicine to heal afflictions that occur in similar body parts? 

For example, walnuts might cure brain diseases, sharp thistle plants could ease acute pain, tomatoes would heal heart-related conditions, and so on. Sometimes it was the shape, other times it was the color, habitat, odor or texture of a natural object that helped confer its connections.  

The theory was that God left hints, and astute humans could study, learn and use the natural objects to prevent and treat diseases.  Starting with the Greek physician Dioscorides, and continuing through the 17th century, the Doctrine of Signatures held that God marked natural objects with an indication, or signature, pointing toward their purpose.  

Sometime the match was obvious, as in the case of Lobaria palmonaria. This lichen, which I observed recently in West Tisbury, is also called lungwort lichen, lung moss, lung lichen, oak lungwort and oakleaf lichen, and only needs a glance to confirm its name and its target organ.  

Lungwort lichen is a quite distinctive, foliose lichen found in rich, old-growth woodlands. Its leafy thallus, or main body, resembles lung tissue with its ridges and lobes. When moist, it is a deep green, though it becomes brown and papery when dry.  

Lichens are known for their two-party system, the marriage of an algae and a fungus, each having its own function, but operating together as a unique organism. Lungwort lichen goes further, committing to a threesome of sorts, with the algae and fungus joined by a cyanobacteria, making this lichen a representative of three different taxonomic kingdoms.  

The algal component allows for photosynthesis, the fungus provides structural support and the cyanobacteria fixes nitrogen. What a powerful combination! Find it on trees — including oaks, maples and beeches — and on rocks.   

The sighting of this lichen was a first for me. It is not super-common, preferring areas with aged, established trees, and has declined in some places due to its aversion to air pollution, reduction or destruction of its preferred old-growth forest habitat and its slow reproductive rate. Some sources suggest that it won’t propagate until it is 25 years old.    

Although lungwort has a great many uses, including medicinal, culinary and industrial, leave it alone to encourage its growth and spread.  This lichen actually does follow the Doctrine of Signatures in that it is believed to be a remedy for lung-related conditions, including coughing up blood, asthma and tuberculosis. Past commercial employment includes its use as an orange dye for wool, as an additive to perfumes and for the tanning of leather. Finally, when it was plentiful, its yeastiness was employed to make bread and brew beer. For wildlife, lungwort lichen serves as nest material for chipmunks and some birds.  

Sixteenth-century physician Paracelsus was a disciple and spreader of the Doctrine of Signatures: “Thou shalt know all internal,” he wrote, “by looking at the outside. God does not want things to stay hidden, which He created for mankind’s benefit. ... And even though He Himself hid it, so did He mark upon it outer, visible signs, that are special marks.”    

It is all unscientific lore, of course, especially since there aren’t enough plants in nature to resemble all the parts of the body nor the different invisible maladies; but it is amusing to imagine that you could, for instance, cure split ends with a nice bowl of angel-hair pasta!

Suzan Bellincampi is director of the Felix Neck Wildlife Sanctuary in Edgartown, and author of Martha’s Vineyard: A Field Guide to Island Nature and The Nature of Martha’s Vineyard.