September in the garden means picking the last of the peppers and setting out napa cabbage seedlings. Then someone hands you a bag of dried seogi that came down from the mountains, and you go looking for a place to plant it — and your hands stop. Those black threads laid over the japchae (stir-fried glass noodles) at a wedding feast: that's seogi. Only seogi isn't a crop you put in a garden bed.
There Is No Seed
The Korean name carries the word for mushroom — seogi-beoseot — but this is no mushroom. It's a lichen, a fungus and an alga living as one body. It sends no roots into soil; it fastens to bare rock at a single point and spreads from there. Its home is the high mountain cliff, where fog and dew come often, and it grows only while it is wet — once it dries, growth stops and it simply endures. It does best between 10 and 20°C (50–68°F) and survives from 0 to 25°C (32–77°F). Cold, it handles well. It grows so slowly that a rock stripped once stays bare for years. So leave the sowing line on your calendar blank, and write gather in its place.
What You Can Actually Tend
Don't make plans to raise seogi at home and harvest it. It's far too slow, and you can't move a cliff face and its mountain fog into a backyard plot. But if your garden has a stone wall or a few large rocks, try leaving whatever lichen has settled on their surfaces alone. A scrub brush or a spray of cleaner wipes out in one pass what took years to take hold. Keep water from pooling around the stone, and leave it a spot that gets shade and moving air together. That's the whole of the tending available to you.
Season, and How to Get It
The gathering season is summer and fall; in the Northern Hemisphere, most of what comes in is picked between July and September. It grows wild in the mountains of Korea, China, and Japan. Even what turns up at market was never farmed — it was pried off rock. Gathering is cliff work, and it's dangerous. Buying it already dried is safer than going after it yourself. And if you do meet it on a mountain, don't clear the patch out. Take only what you need and leave the rest. That rock will take years to go black again.
Soaking and Slicing
Soak dried seogi in lukewarm water until it softens. Then work through these in order.
- Pull off the navel at the center of the underside — the tough point where it gripped the rock.
- Rinse until no grit is left, then squeeze out the water.
- Slice it into the finest threads you can. Cut thick, it chews tough.
- Dress it lightly with nothing but sesame oil and salt, then turn it briefly in a dry pan to drive off the moisture.
Prepared this way, the black threads go over japchae or get worked into tteok (rice cake) dough. For sinseollo — a tableside hot pot where ingredients are arranged over broth and simmered — and for jeongol (a shared hot pot), add it at the very last moment so the strands keep their texture. The black doesn't bleed even in boiling broth, so it stays its own color against yellow jidan (thin egg-crepe strips) and red silgochu (slivered dried chili). Keep the seasoning light and it won't fight the other ingredients.
The Old Record, and What's in It
The Donguibogam, the classical Korean medical compendium, lists it in the vegetable section as seogi (石耳). It calls the nature of the plant cold, while noting that others describe it as neutral, and gives the taste as sweet and the plant as nontoxic. It places its origin on the rock cliffs of famous mountains, and adds that some people call it yeongji (靈芝). The yeongji meant there is not what we call the reishi mushroom today. Seogi means ear of the rock.
On the chemistry side, there have been repeated reports of gyrophoric-acid-type lichen acids and polysaccharides isolated from lichens in the genus Umbilicaria, along with measurements showing that the composition differs from species to species. That is as far as it goes: compounds separated and identified, not effects confirmed in the body. At the table, what you can reasonably count on is the dietary fiber behind that chewy texture, and the minerals lichens accumulate. The old medical text's descriptions don't line up with how we judge these things now, so we don't carry them over as health claims.
Today, set a handful of dried seogi in lukewarm water. Pull the navels tonight and slice it fine, and sometime this week you'll have a black ribbon to lay across japchae or a round of tteok.
Sources: Donguibogam, vegetable section, seogi (石耳) · National Institute of Forest Science · Korea National Arboretum, Korean Biodiversity Information System
