I love where I live. The four seasons, the incredible hiking opportunities, the unique geology and of course, those Great Lakes. Western New York never disappoints, but every year at around this time, I have a tough time. Everything seems to have the same color and literally everything looks the same. The plants remain dormant, most mammals are still sleeping, and the first fungi to fruit are still months away. Dreary is an understatement, but us students of the forest floor must remain calm and keep learning, for the growing season is around the corner! It is times like these at which I reminisce about my hiking adventures and think about some of my favorite fungal encounters. One of my favorite organisms is from the genus Leccinum. Unfortunately, little genetic work has been carried out in the United States on this genus, so to identify the organism down to species, especially on the East Coast is nearly impossible (right now).
My first encounter was incredibly exciting. Hiking through a mixed hardwood/coniferous forest in Western New York, I stumbled upon a dense stand of white pines. I had a really good feeling before entering the stand, and was hopeful to unearth some ectomycorrhizal fungi. Prior to stumbling across this congregation of pines, the fungal foray was exceedingly fruitful. The hike had already attained a legendary status with the insane amount of species I found. I was so glad to have shared this adventure with my close friend Justin, who is not a mycophile, and my loyal dog Stella. I love it when people outside of the field get excited about finding mushrooms, and it was actually my friend Justin who spotted the first Leccinum individual.
In a 30-meter by 30-meter plot of forest floor within this stand of white pines, there were about 300 Leccinum mushrooms! Their fruiting was so aggressive! I’ve seen patches of mushrooms that exceeded this number of individuals, but members of this genus grow extremely robust! Biomass wise, this was the heaviest patch of mushrooms I’ve ever encountered, even to this day. Sights like this make me feel like Alice in Wonderland. I could only imagine the quantities of resources these fungi and pines shared. Seeing this sight, I was reminded of how important the mutualisms that take place beneath the forest floor are. The same interactions that largely go unseen.
In several articles posted on this website I mention how plants offer a sugar reward to their fungal counterpart in return for scant soil nutrients like nitrogen and phosphorus. The fine hyphae these fungi have can maneuver around the variable soil environments, fitting into tiny spaces to locate these rare macro and micro nutrients. Up to 20% of the plants products from photosynthesis is allocated to the organisms living amongst its roots! This clearly shows the importance of this mutualism. But sending nutrients to the host plant is not the only service these fungi provide. More and more research is being published that reveals how mycorrhizae enhance drought resistance in their host plant.
A study carried out in 2017 by Dachuan Yin, Ruiqing Song, Jinyu Qi and Xun Dengshow the importance of ectomycorrhizal fungi establishment on pine seedlings during periods of water stress. These researchers found that mycorrhizal colonization was significantly higher in plants facing drought conditions, compared to well-watered conditions. Additionally, they found that the plants with the fungal symbiote experiencing drought conditions grew better than plants in well-watered conditions without mycorrhizae. The sapling stage is the most difficult period these immature pines will ever face, but with the help of their mycorrhizal symbiote, they can withstand periods of drought. Fungi, like the Leccinum mushrooms I found aid plants both nutritionally, and from a water limitation standpoint as well.
The rust-brown bolete mushroom I located in that stand of pines is without a doubt a Leccinum species. Most mushrooms in this genus have small, blackened rigid projections on its stipe called scabers. Many species of Leccinum have the same reddish-brown cap, and although they have been described in great depth throughout Europe, their taxonomy in North America, especially on the East Coast is not up to date. The specimens I found on that glorious hike look strikingly similar to the widespread European species called Leccinum aurantiacum, but it is very likely that this is a different species altogether. Experts are simply calling this Leccinum species Leccinum sect. Leccinum.
So even though the taxonomy of this species is a huge mess, it is one of my favorite forest floor inhabitants. I don’t even know the exact species, but it was truly love at first sight. Remembering my first encounter with these mushrooms brings me so much joy, and fills me with excitement for the fungal forays to come. These amazingly robust mycorrhizal mushrooms not only provide their host plants with nutrients root hairs have a hard time accessing, but water during periods of drought. By aiding trees during their most vulnerable sapling stage, species like these will allow forests to function during these modern times dominated by human disturbances.