Crepidotus crocophyllus, the orange crep

Tom Volk's Fungus of the Month for July 2007

by Tom Volk and Jon Palmer

Please click for the rest of Tom Volk's pages on fungi

Crepidotus crocophyllus "Oh no! We went on a foray, and all we found were *%^*@&%&* Crepidotus!
I was so disappointed"

As you might guess from that actual overheard statement, Crepidotus suffers from its misunderstood boringness. So far as I know, none of the species are edible-- but none of them are poisonous either. However, our data are far from complete because almost no one ever tries them! Most (all?) of the species are rather small, delicate, and watery and would cook down to almost nothing anyway. They could be called the "emo kids" of the mushroom world.

However, I am here to tell you that you should be grateful for Crepidotus species. Despite their milquetoast fruiting bodies, the mycelium must really be very hardy and able to withstand dry conditions. Crepidotus usually grows on very old, very rotten logs that dry out easily. Yet it is in these dry conditions that you can often find Crepidotus fruiting bodies. The mycelium must be able to survive these harsh times while it is decaying the wood. Thus, despite its persistent mycelium, the fruiting bodies are pretty delicate and seem to be falling apart. In fact the genus name Crepidotus means "cracked ear." You may recognize the similarity to the word "decrepit," which literally means "thoroughly cracked up." The epithet crocophyllus means "saffron colored gills," very appropriate in this case, at least when the mushrooms are young.

disappointed collector pointing to one of the few oyster mushrooms she foundCertainly Crepidotus crocophyllus is the most beautiful of the Crepidotis species I have seen, although there are said to be some spectacular tropical and subtropical species. It is relatively easy to distinguish because of the saffron-orange color of the gills and the hairy cap, although the hairs may whither with age. The basidiospores are round (globose) and brown in color but are otherwise unremarkable. It's a fun species to find, especially when you turn it over to see the color. It is not known to be edible, but it is not reputed to be poisonous either.

There are many other species, especially in the tropics. One recent study was by Cathie Aime, who did her M.S. thesis on the genus Crepidotus and other members of the Crepidotaceae at Virginia Tech with Orson K. Miller Jr. in 1999 and her Ph.D. thesis in 2004. There are about 150 species worldwide. "Crepidotus now represents those astipitate agarics that possess pigmented spores lacking a germ pore, and usually lacking pleurocystidia. Many brown-spored astipitate genera have been historically confused with Crepidotus, but the presence of a germ pore and/or pleurocystidia in these genera (for example, Melanotus Pat.) readily distinguish them as allies of other families." For more information on the Crepidotaceae, see this paper: M. Catherine Aime, Rytas Vilgalys and Orson K. Miller Jr. 2005. The Crepidotaceae (Basidiomycota, Agaricales): phylogeny and taxonomy of the genera and revision of the family based on molecular evidence. American Journal of Botany. 92:74-82.

Most of the other species of Crepidotus are white to tan and pretty unremarkable. Because of their missing stalk and white color, some collectors can confuse them with Pleurotus, oyster mushrooms. At the right you can see such a disappointed collector, picking up one of the only two oyster mushrooms she got on her collecting trip. At this foray she learned to distinguish Crepidotus species by their frailness and their brown spore print. Sometimes, however, the spore color does not show on the gills until the mushroom is very mature. In such cases the gills would appear white to tan, but if you do an actual spore print by patiently laying the mushroom down on a piece of paper, the spore print would be deep brown. You will recall that Pleurotus species have a white spore print and are usually much tougher. Most of the time oyster mushrooms also have a short eccentric (off-center) stalk. So after all that work in collecting these mushrooms, the disillusioned forayer went home with just a mouthful of oyster mushrooms. I sure hope she found some another day.

It is difficult to distinguish many of the species of Crepidotus without using microscopic characters. In our key below, we have included here eight of the more common species. Jon Palmer made this key a couple summers ago when it was dry and all we found were Crepidotus. In order to accurately key the species we are forced to use microscopic characters, especially basidiospore size and shape. The likelihood is minimal that anyone without a microscope would really want to key these species anyway, but you can try! Good Luck. Let us know how it works for you.

Key to eight species of Crepidotus in North America      by Jon Palmer and Tom Volk

1. Fruiting body somewhat brightly colored (red to orange to yellow), colors may fade with age

     2. Pileus fan-shaped scarlet to cinnabar-red, cuticle dry; gills subdistant, concolorous with pileus; known from Northeastern North America; spores dull brown, 7-10 x 5-6 µm …………………………………….………………………….....…C. cinnabarinus

     2. Fruiting body lacking above characteristics, usually more orange in color….…….3

          3. Pileus ochre-brown convex to fan-shaped often with fibrils or scales; gills crowded brightly colored yellow to orange (at least when young) widely distributed, spores roughened, 5.5-6 x 5.5-6 µm …………………..C. crocophyllus

          3. Pileus fan-shaped and bright orange-tawny; gills subdistant, salmon to dull orange; known from the Southern U.S.; spores salmon-pink, smooth, 5.5-7.5 x 5-7 µm ..……………......C. subnidulans

1. Fruiting body lacking red or orange tones, mostly whitish to ochre (may have orange to brown fibrils or scales)

     4. Minute species, pileus 3/16 - Ύ in.; gills radiating from a central to eccentric point; spores smooth, lance-shaped to elliptical, 6-8 x 3-4 µm ………………....C. herbarum

     4. Pileus typically larger by maturity, 3/8 - 5 in. ………………………...……………5

          5. Cap cuticle gelatinous-elastic and easily peelable, pileus hygrophanous, fibrillose when young becoming smooth with age; spores smooth, 7-10 x 4.5-6 µm; clamp connections absent…………………. C. mollis (= C. fulvotomentosus)

          5. Cap cuticle not gelatinous-elastic and peelable (although sometimes it appears that cuticle is peelable, it lacks the elastic consistency) …………………..……..6

               6. Gills crowded and radiating from point of attachment with substrate (Pleurotus like); pileus white turning pinkish-tan to brown with age, 3/8 - 1½ ; spores 4-5.5 x 4-5.5 µm …….……….…….……….…….………. C. applanatus var. applanatus

               6. Gills NOT radiating from point of attachment ………………………...7

                    7. Spores globose, 5-7 x 5-7 µm; pileus milk-white sometimes with black spots with age; clamp connections present ….....C. maculans

                    7. Spores elliptical, 7-9 x 4-5 µm; reported on Hickory from Tennessee but probably across the Southern U.S.; pileus whitish, fan-shaped, 1½ - 5 in. ………………………………...C. maximus

 A &B = Crepidotus applanatus C=Crepidotus maculans D= Crepidotus mollis.  photos B& D by John Plischke III Here are some of those other species. A & B show Crepidotus applanatus . In A the mushrooms were quite wet, and in B they had started to dry out. They are said to be hygrophanous. Figure C shows Crepidotus maculans, and D shows Crepidotus mollis. Photos B & D are by John Plischke III, who is one of the best mushroom photographers around.

I hope you enjoyed learning about Crepidotus crocophyllus and its relatives. Next time you're in the woods, collect these little beauties and try to key them out. It'll be fun!!

If you have anything to add, or if you have corrections, comments, or recommendations for future FotM's (or maybe you'd like to be co-author of a FotM?), please write to me at my email address

Jon Palmer This month's coauthor is Jon Palmer, my former graduate student. Jon got his M.S. degree with me in December 2006, winning the "Best graduate thesis" award from the University of Wisconsin-La Crosse for 2006-2007. Jon is currently in a Ph.D. program in Nancy Keller's lab at the University of Wisconsin-Madison working on a fungal genetics project with Aspergilllus. This page and other pages are © Copyright 2007 by Thomas J. Volk, University of Wisconsin-La Crosse.

Learn more about fungi! Go to Tom Volk's Fungi Home Page

Return to Tom Volk's Fungus of the month pages listing