Good afternoon team. This week's mushroom is Melogramma gyrosum, formerly known as endothia radicalis, and commonly known as the orange hobnail canker. There isn't too much information available on this fungus, and it's been taxonomically reclassified a few times which further convolutes research, but it's certainly distinct looking and fairly common in the park. This specimen was found on limbs that were pruned out of an oak on the west lawn in the Ramble on 1/21/2021. It's also on the pruned limb of an oak east of where the gill runs into the lake.
M. gyrosum is found in the Eastern US and Europe. It seems to fruit in the fall and is seen throughout the winter because of its conspicuous orange color. It is thought to be a plant pathogen that infects a variety of hardwoods - predominantly oaks (Quercus) - but, per Daniel Atha of NYBG, there isn't conclusive evidence that it is a pathogen so for that reason I won't suggest as such. Daniel suggests that it could be an "opportunistic symbiont" that appears at the site of infection and feeds on necrotic tissue, possibly even isolating the necrosis and helping to clean said infection. Nonetheless, wherever you find M. gyrosum you can infer that the host tree is dealing with an ailment. Whether that's due to previous injury/infection or the fungus itself we cannot say for certain.
Enjoy the gorgeous spring weather this week,