As the rainy season is (finally) getting started in Southern California, you may notice mushrooms popping up around town. Mushrooms vary a lot in form—from small, delicate caps to large, marshmallow-like masses. They can also vary in function, from breaking down organic matter to sharing nutrients with host plants. All mushrooms, however, play an important role in healthy ecosystems.
Below is a short introduction to the 10 most commonly seen mushrooms in Southern California. As always with fungi, be careful with identification, and reach out to an expert or check out our resources below for more information. You can also add mushroom sightings to iNaturalist, especially the Fungi of San Diego County and Fungi of the California Floristic Province projects, and expert identifiers can help you determine the mushroom species you’ve seen.
The above diagram will help you explore mushroom anatomy which will help you improve your mushroom ID skills. Illustration credit: Mallory Hammond.
This mushroom is often called "the most commonly eaten toxic mushroom in North America" because it looks remarkably similar to a number of other button and field mushrooms. It is distinguishable by its green spores (a rarity in local fungi) and the smooth white cap on top covered in small brown scales. The cap goes from rounded (convex) to flat as it ages, and the gills on the underside range in color from white to green/gray. The stem (technically called a “stipe” when referring to mushrooms) is straight with a ring near the cap. It breaks down dead or decaying organic matter (called saprobic) and can often be found on lawns. Photo credit: Rachel Allingham.
Western Hardwood Sulfur Shelf is one of the most commonly seen fungi in Southern California for a reason: it's large, bulbous, and bright orange/yellow. It is related to the famous "Chicken of the Woods" (Laetiporus sulphureus), but the group of related species, also called a clade, were split into distinct species in 2001. The various species can be distinguished by location and host plant. Our local species L. gilbertsonii has yellow pores, grows on hardwood trees as opposed to conifers, and is primarily found on the West coast of North America. When dried, it can appear brown or pale white. Photo credit: Ariel Hammond.
Known to glow in the dark (bioluminesce), these fungi are a true delight to behold. The unusual coloring of bright orange with olive undertones (especially in the gills) means that a single cap can be described as yellow, orange, red, olive, purple, and brown all at the same time. They typically have red and/or orange fibrous streaks on the caps, and edges may appear "burnt" or dark red, brown, or black. Found near tree roots or stumps, they may reappear in the same spot annually. A true California original, they are endemic to and widely distributed throughout the California Floristic Province. Photo credit: Ariel Hammond.
One of the most commonly seen fungi in the world, this bracket fungi grows off of tree stumps and logs and displays bands of color across the cap. It is mistaken for Turkey Tail (Trametes versicolor) so often that one of its common names is "False Turkey Tail." Hairy Curtain Crust is much smaller than Turkey Tail and has many distinctive hairs on the cap, which is why the word "hirsute," meaning "hairy," is in the taxonomic name. The colored stripes on the cap range from white/cream to orange/yellow to gray/green/brown. This species can withstand dry environments for long periods of time and will refresh after rain. It can also be parasitized by another fungus called Golden Ear (Naematelia aurantia) which looks like yellow jellied curds! Photo credit: Ariel Hammond.
Tiny and fuzzy capped with unique “split” gills underneath, this is also one of the most commonly seen mushrooms in the world. Like Hairy Curtain Crust, dried specimens may last for years on a host plant, only to revive with water. The gills are white/pink/grey/brown colored and release white spores. They tend to grow in clusters on both hardwoods (oaks, maples, sycamores, etc.) and conifers, and are occasionally seen on non-tree plants. This fungus is a great example of the importance of looking at all sides of a mushroom to identify it, since no other fungi species is known to have gills quite like this one. Photo credit: Ariel Hammond.
Also called the "Petty Fieldcap," this little brown mushroom (0.4-1.2") is seen most often in disturbed habitats, such as grassy lawns or mulched areas. The cap is smooth (occasionally sticky), begins rounded and flattens with age, and is described as cream/yellow/tan/brown at different stages of maturity. The gills also go from cream/yellow to brown as they age. One distinctive feature is the extremely thin stem which lacks a ring around it. The mushroom is saprotrophic, breaking down dead or decaying organic matter. Photo credit: Alan Rockefeller.
With their rose-pink gills, smooth white caps, and preference for growing on lawns, Stubble Rosegill can be a fairly easy mushroom to identify when they are young. As with many mushrooms in the Agaricales order, the caps begin rounded and then flatten as they age. In this species, the gills eventually turn a dark brown due to their brown spores. It can also be distinguished from similar looking button-type mushrooms by the tiny brown spots on their caps. Photo credit: Alan Rockefeller.
This cute mushroom is also called “Sunny Side Up” due to the characteristic dark yellow center of the cap. It is a fan of grassy areas and manure, and so delicate that it can fall apart, dry up, or get eaten within hours of fruiting. As opposed to other fungi caps that darken with age, this species begins with a vivid yellow/orange color and turns pale as it matures. The gills, however, operate in reverse, beginning yellow and browning with age as the fungus releases its brown spores. Photo Credit: Alan Rockefeller.
This iconic fungus can be misidentified due to a couple of similar-looking species (especially Hairy Curtain Crust). Turkey Tail is a bracket fungus that grows out of decaying logs and dead tree stumps, breaking down organic matter and lignin. The name "versicolor" means many colored, and this fungus displays bands of different color ranging from cream to brown, though blue is a distinctive color for this species. It grows in overlapping layers and is distinguished from Hairy Curtain Crust by its larger size and the underside (hymenium) of the fungus: it has spongy pores underneath as opposed to a thin, crust-like texture. Photo credit: Shahan Derkarabetian.
Formerly called Psathyrella candoleana, this mushroom makes up for its small size by growing in large groups. Often found in grassy lawns and urban areas, it is distinguished by the asymmetrical cream/yellow/tan cap that often has tiny white bits stuck to the edge (margin). These tiny pieces are remnants of the veil that encapsulates the growing young mushroom before it breaks open to reveal the specimen inside. The gills change from white/cream/gray to purple/brown as they mature due to the purple/brown color of the spores, while the stem is typically a bright white. Photo credit: Alan Rockefeller.
Posted by Ariel Hammond, Director of Research Library and Archives.
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