August Nature Almanac: All Hail To The Emperor
By Ruth Carol Cushman with Stephen R. Jones
August 2025
Did you know that Colorado has a state mushroom? Commonly known as “The Prince” or “The Emperor,” Agaricus julius became our state mushroom on March 31, 2025, when Governor Polis signed a bill that had been in the works for four years.
Agaricus julius growing in its native habitat. Photo by G.Sanchezz (WikiCommons, CC BY-SA).
Greg Sanchez, then President of the Colorado Mycological Society, started the momentum to establish a state mushroom. We already have a state tree, a state flower, a state insect, a state mammal, and even a state rock, plus several other state symbols. But not a mushroom. In fact, only three other states (Oregon, Minnesota, and Texas) had such a designee.
A public opinion poll in 2023 favored other mushrooms. Boletus rubriceps (Rocky Mountain or ruby bolete) a relative of B. edulis (porcini mushrooms) arguably the most delicious wild mushroom of all. Cantharellus roseocanus (a chanterelle) is also delectable. And Amanita muscaria (fly agaric) which is a source for psilocybin and can be fatal causing damage to the liver.
For various reasons, these mushrooms didn’t quite fit the bill, and a committee of mycologists chose Agaricus julius. A bill was passed by both the House and the Senate last January and signed into law a few weeks later.
Agaricus julius, first described by Richard Kerrigan in Agaricus of North America (2016), is the Rocky Mountain relative of the West Coast species A. augustus, commonly called “The Prince.” Because collectors identified A. julius as A. augustus for decades, Kerrigan suggested the new mushroom be called “the Emperor formerly known as Prince.”
Our favorite mushroom guidebook, Vera Evenson’s Mushrooms of the Rocky Mountain Region, was published in 2015 before A. julius was even described. Therefore, it doesn’t include our new state mushroom, although it does include A. augustus.
The Emperor, which resembles a portobello mushroom, is found in high elevation spruce-fir forests of the Rocky Mountains from New Mexico to Alaska. When young, this mushroom has pink to pinkish gray gills, which turn brown as the mushroom ages, and is covered with a cottony veil. As the mushroom matures, the veil breaks away from the cap and forms a ring around the stalk (also an attribute of some poisonous mushrooms). The scaley, brownish cap--2 to almost 6 inches wide--can become about the size of a dinner plate. When cut, the flesh stains slightly yellow, and the spore print is brown to blackish brown.
Harvested Agaricus julius. Photo by ColoradoMushrooms (WikiCommons, CC BY-SA).
In the announcement of the state mushroom, Governor Polis said, “Our state mushroom has coloring similar to a portobello, a cherry-almond aroma and it’s delicious." That said, we urge caution in eating wild mushrooms. Our rule is never eat ANY wild mushroom unless you know it well enough to call it by its scientific name and know there are no look-alikes. For many years we harvested and relished wild mushrooms. Although we enjoyed other Agaricus species we never—to our regret—tasted A. julius.
If you go mushroom hunting, August is the prime time of year, especially in high elevation spruce/fir forests. Many cookbooks, as well as the Colorado Mycological Society website, have fancy mushroom recipes, but we prefer them simply sautéed in butter with a bit of onion.
To learn more about mushrooms, visit the annual Colorado Mycology Society Mushroom Fair at the Denver Botanic Gardens on August 10th from 11–5pm (event is free with purchase of Denver Botanic Garden entrance ticket. Tickets are timed entry and can sell out). Experts will be on hand to help with identifications.
You can also visit the Colorado Mycological Society and sign up for one of their forays. Going on a foray with the experts is the best way to learn.
It’s fitting that Colorado, one of the first states to legalize psychedelic mushrooms, now has its own official state mushroom, albeit A. julius is not a source of psilocybin.
Editor’s Note: Before going mushroom hunting, always check the regulations for when and how you can harvest them. In Colorado, no collection is permitted in national parks or monuments and in state parks. A permit is needed for most USFS lands (even for private consumption; often free). Call your local USFS ranger district for details. Collection on BLM land for private consumption is generally permitted. Collection on other public lands (open space, etc) will vary by jurisdiction, check with each entity before harvesting.
Other August Events
Chokecherries, a staple food of indigenous peoples of the mountains and plains, ripen, stimulating the holding of Sun Dances and other sacred ceremonies.
Shorebirds migrating southward stop over at mud flats at Union Reservoir, Stearns Lake, and Sombrero Marsh.
Migrating Pinyon Jays and Sage Thrashers gather in Dowdy Draw and other north-facing foothills canyons.
Monarch butterflies descended from adults who migrated north to Colorado during May and June mate and lay eggs on milkweed plants. Their offspring will comprise part of the autumn population that will fly all the way south to the high mountains of Michoacán to overwinter as adults. In late July, we counted a dozen monarchs along the South Boulder Creek trail originating on the west side of SH 93 south of Boulder.
Young Northern Harriers begin to disperse from nesting sites in wetlands surrounding Boulder Reservoir.
Colorado chipmunks born in late May or June appear above ground.
Gentians are blooming from the prairies to treeline. Look for bottle gentians in the foothills and for arctic, blue, and twisted in subalpine meadows.
Semipalmated Sandpiper on a migration stopover. Photo by Gerhard Assenmacher.
August 2, 2025 - Text edited with updated discussion of harvesting regulations in Colorado.
Nature Almanac is a monthly series by Stephen R. Jones and R. Carol Cushman, along with other guest contributors. Ruth Carol Cushman and Stephen Jones are authors of A Field Guide to The North American Prairie (Peterson Field Guides) and Wild Boulder County: A Seasonal Guide to the Natural World.