Here’s the final entry in our series, Mushroom of the Month, brought to you by Michael W. Hopping, co-author of A Field Guide to Mushrooms of the Carolinas:  A Southern Gateways Guide — this month it’s Cortinarius argentatus.

Mushrooms in the wild present an enticing challenge: some are delicious, others are deadly, and still others take on almost unbelievable forms. A Field Guide to Mushrooms of the Carolinas introduces 650 mushrooms found in the Carolinas–more than 50 of them appearing in a field guide for the first time–using clear language and color photographs to reveal their unique features.

A Field Guide to Mushrooms of the Carolinas is available now in both print and ebook editions.

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Cortinarius argentatus

Vision is a curious thing. There is seeing, and then there’s awareness of what’s being seen. It’s as if our minds were in the habit of serving us executive summaries, omitting a lot of potentially irrelevant detail. Your co-worker, Alex, seemed tired this morning. What color was his belt? Was he wearing one? The summaries simplify life, usually in a helpful way. But mushroom hunters learn the inadequacy of any summarizing habits we have about fungi. Awareness of color, size, and the presence of a cap and stalk is simply not enough. We need details, the sort of details that may remain invisible until we turn off our mental summarizers.

Take silver-violet, gilled mushrooms for instance. If you’ve never seen such a thing, September is prime time to remedy that. Try deciduous woods with rich soils or moist and shaded landscaped areas. Well-watered lawns are another possibility. This package of season, color, and habitat preference fits a popular edible species, Lepista nuda, aka the Blewit. But not so fast. Blewits share the autumn woodlands with silver-violet members of the genus Cortinarius. Corts can be poisonous. Among the Blewit’s closest lookalikes is Cortinarius argentatus.

The 5-9 cm cap diameter of Cortinarius argentatus is the same as a small to medium-sized Blewit. While Blewit caps tend to be a bit damp and sticky, those of C. argentatus are dry with a silky sheen. Atmospheric conditions can obscure this distinction. Fortunately, two other differences are weatherproof.  Cortinarius argentatus and its cort cousins protect developing gills behind a temporary barrier known as a partial veil. It radially connects the mushroom stalk to the outer margin of an immature cap. When the cap expands toward maturity, the partial veil tears free from the stalk or cap margin, exposing gills that are now ready to drop spores. Oftentimes, a partial veil is a sheet of solid tissue that ends up dangling from the stalk as a skirt. But in most corts, partial veils take the form of radially arranged cobwebs. This style is referred to as—wait for it—a cortina. After the mushroom cap opens, a few cortina threads typically remain attached to the stalk, where they hang limply and acquire a rusty brown coat of spores. Close inspection of a C. argentatus button reveals the intact cortina. On mature stalks, look for limp, rusty threads and/or rusty smudges of spore deposit.

Some gilled species have partial veils; others don’t. Blewits lack a partial veil of any kind. No skirt or cortina threads on the stalk, no ragtag remnants of anything hanging from the edge of the cap. Blewits also have pinkish buff, rather than rusty, spores. A spore print will reveal that.

Too often, wild mushrooms are exiled to a psychological fogbank, ominous, seldom glimpsed, best avoided. That needn’t be the case. If you’re willing to stop and look, observable differences are usually enough to bring a species into focus. Once introduced, other questions arise. How do these guys make their living? What roles do they play in their ecosystem? Have people found them useful and, if so, how? With a little help from a trusty field guide and perhaps a veteran expeditioner, you’ll be safely able to explore a whole new dimension of the natural world.

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Michael W. Hopping, a retired physician and author, is a principal mushroom identifier for the Asheville Mushroom Club. You can read his previous blog posts here.