This quick update will cover our recent project with Dr. Rytas Vilgalys, Professor of Biology at Duke University. Dr. Rytas was kind enough to do some PCR DNA and get an ITS sequence of some of our various collections of Pleurotus that were found growing on pine wood.

Over the past 2 years, James and I have been on the hunt for an oyster mushroom that grows on pine. To explain, I should first give a little background about these particular fungi. They tend to favor deciduous wood, especially poplar trees in Colorado. To most fungi, pine wood isn’t something easy to eat. Coniferous trees contain natural resins that tend to contain chemicals that are quite anti-fungal. This does not mean that fungi cannot eat coniferous wood, it is just quite difficult for them to do. However, Pleurotus are special fungi. They have discovered a quite efficient method of decomposing their substrate, excreting powerful digestive enzymes able to breakdown many different types of freshly cut wood. There is even a type of Pleurotus that can grow on cactus skeletons! The Pleurotus that James and I had found were growing from the cut stumps of pine trees and a spruce log growing at 10,000′ in elevation. These were cultured in our lab in Denver and were eventually sent to Dr. Rytas. He was interested in them because of their unique habitats they were found growing in and was wondering, as we were, if they were a possible new species of Pleurotus. He also received a few control collections of Pleurotus pulmonarius from various locations in the state, growing from cottonwood trees. These were tested against the mushrooms that were found growing on conifers. This testing is basically done by taking known sets of genes from a specific species of fungi and testing samples of DNA against those genes to see if they are similar enough to be the same genetic group (hopefully that wasn’t too over simplified?). Much to our surprise, every specimen came back as P. pulmonarius! It is well documented that P. pulmonarius grows occasionally from conifer, but these specimens also had unique morphological features that were distinctly different, even with indoor grown mushrooms in a controlled environment! Just goes to show that morphology sometimes can tell you very little about what type of fungi you have. We now know that our cultures of oysters collected from these conifer habitats are P. pulmonarius, but have somehow developed a unique set of digestive enzymes to deal with the oils in the wood that tend to inhibit fungi.

The reason James and I are extremely interested in pine loving oysters is because the Rocky Mountains are plagued with a pine eating beetle that is destroying our forests by the entire mountainside. The general way to deal with this problem (due to the extreme fire danger it creates) is to cut down the infected trees and pile them in large piles. They are used mainly for fire wood, but the pine loving  mushrooms would decompose the wood much faster, creating larger soil depth. Paul Stamets has a discussion in his book, Mycelium Running, about the honey mushroom and its method of creating a deeper humus depth. Many of these plagues, whether they be a fungus or an insect, may look very disastrous to the environment to humans. This is only because of our perception of time. The trees that once stood as a forest are now decomposing, increasing the potential of the forest to create more life. As soil depth increases, the forest can house more and more plants. We would like to make these Pleurotus part of the solution to this large problem we are facing today.

Now that we have received our spring rains, the Colorado mushroom season has begun. I have seen quite a few Coprinus comatus around the city, but if you look in your local riparian areas you may come across the infamous oyster mushroom, Pleurotus pulmonarius in most cases, growing on dead or dying deciduous trees and stumps. Pleutotus pulmonarius is the most common species in lower elevations, favoring cottonwood trees. Colorado also has a couple other species, Pleurotus populinus probably being the next most well known. It is found growing on aspen and has more delicate ‘shelves’. Another species, Pleurotus dryinus has also been found in Colorado. It is usually has less of a clustering habit, longer and larger stems, a mostly centrally attached stem and a very distinctive cap. All oyster mushrooms have a very distinctive shape, sometimes growing in fans that are shaped closely to an oyster shell. They also are known to have a slight shellfish odor, making the common name ‘oyster mushroom’ very fitting.
To make sure you have a Pleurotus species take a spore print. Put a mature mushroom cap on a piece of white paper and with your finger, moisten the cap with a little bit of water. Then put a glass over top of it to reduce air flow around the cap so the spores fall off of the gills and onto the paper. Leave it over night until the next morning. You should be left with a gray or gray/lilac spore print.
James and I have been finding quite a few oysters out already, as the weather is permitting them to fruit. They are just beginning as most of the logs we know have large amounts of mushrooms have yet to show major signs of fruiting. Nonetheless, there are still pounds of mushrooms already out and ready for picking!
Below is a gallery featuring some of the oyster mushrooms we have found in the past few days. Bert, the newest member of Amateur Mycology is shown above with a particularly large cluster of Pleurotus pulmonarius I found on a cottonwood stump yesterday in Boulder. He brought us to a couple other oyster mushroom spots as that were very interesting! Stay tuned for an Amateur Mycology Video Magazine episode featuring our early oyster hunts!
P.S. No morels seen yet, but we will keep you posted. Still to early.

Yesterday, James went out and found a Polyporus squamosus, the dryad’s saddle, fresh and still in button stage. In February we found some Flammulina velutipes fruiting on our oyster and enoki stump in Littleton, however, also known as the winter mushroom, Flammulina velutipes can be found in almost every month of the year. This morning I went out to my earliest Coprinus comatus spot in the front yard, and sure enough, there were 4 mushrooms! Now 4 mushrooms may not be very many, and this particular spot is watered by the sprinklers in the mornings. But every year they pop up in this spot, mushroom season has officially begun. If you search wetter areas, in particular places in the city where they have just turned on the sprinklers, you should have a good chance of seeing some fungal life. Pleurotus, Flammulina, Coprinus, and maybe few Agaricus should be around. Another good place to start looking is around creeks and rivers along wetter areas, especially spots with a good seepage. We will keep you updated on the progression of the Colorado season as it goes along. Morels should be popping up within the next month, along with all of our early spring fungi. If you haven’t already, check out my post on Morel habitat for more information. Asparagus should also start sprouting up soon as well! Good luck out there and happy spring!

Our trip was a blast. It was very nice to be looking for mushrooms so early in the year compared to what we are used to out here in Colorado. However, the drought conditions in Texas made searching for them a little more difficult than in years previous. We learned that last year’s Morel season was the best they had seen in 15 years. Had we known this, we would have probably waited to go out to Texas until a different year to look for Morels specifically. So we switched gears and searched for city mushrooms in heavily watered areas. This technique gave us some good success. We found quite a few different genera most all a little past their prime, but there were a good handful of edible and living samples that we brought back and cultured on Thursday of this week. I will give you a better summary of the mushrooms we found in the next article.

If you would like to see some of the samples of fungi that were found in Texas last week, make sure you attend the Colorado Mycological Society meeting this coming Monday at the Denver Botanic Gardens. The meetings start at 7pm and usually wrap up around 9pm. We will be displaying dried samples of Ganoderma, Pleurotus, various Polypores, Earthstars, Lentinus, Lactarius and a few others that were found last week in Austin, Athens, White Oak, and San Antonio. We will also be displaying a few fruiting grain jars of Pleurotus columbinus as well as bags of oyster mushroom spawn made with green techniques.

On another note, our Pink Oyster mushrooms came from Kauai Fungi yesterday for our project that we are doing at a few botanic gardens. Kauai Fungi was kind enough to donate a spawn bag of their tropical variety of Pleurotus djamor to our project. We plan to do a fungi demonstration inside a tropical conservatory. We also just acquired a culture of the Golden Oyster, Pleurotus cornucopiae. I think the two fruiting together would be stunning.

The bags of oyster spawn we made before we left for Texas are starting to form primordia! (primordia are baby mushrooms) This means they are already eaten through their substrate and are starting to want to fruit! We expanded them 12 days ago, so this says to me that our ‘Cold Pasteurization’ concept works just as fast as standard pasteurization methods! Stay tuned for a detailed description of this project, from start to finish, within the month! The bags of spawn are destined for Jackie’s Farm for expansion and fruiting, and if you take one of our seminars this summer, coming to a backyard near you!