05/16/2024
Prosthemium neobetulinum (formerly Asterosporium betulinum)
This strange black fungus can be found growing all over Chicago. It grows on river birch trees (Betula nigra). We’ve found it on MOST of the broken river birch branches we’ve scooped off the ground. It’s usually growing right where the branch snapped, and doesn’t seem to grow much further up the branch.
Oddly, this fungus hasn’t been collected in the United States since the 1930s. We have a collection from Graceland Cemetery being DNA sequenced to confirm the ID for our collections.
It seems plain to the naked eye, but has an insane micro-morphology. The conidia (asexual spores) are stellate, or, star shaped. The 4-pronged conidia are fairly unique and very photogenic. We’ve observed the conidia to soak up lactophenol cotton blue, staining the tips of the prongs.
Our friend was kind enough to lend us his nice microscope and micrography setup for the summer. That’s where we got these cool pics!
The sexual form of this fungus has never been observed. So, it either always reproduces asexually, has an unknown morph, or, the sexual morph is already known but the relationship between the two (one) has never been noted.
Regardless, it’s one of the cooler fungi we’ve found in Chicago and shows that sometimes a closer look can unveil a long-hidden message from the mushroom world.
Comment on this post if you’d be interested in a beginners fungal microscopy workshop!
______________________________________