The secrets of an earthstar mushroom

As you know, this is an earthstar mushroom. Last November I posted my first blog titled “Mushrooms like stars on the ground”. This mushroom is an ectomycorrhizal fungus that has a symbiotic relationship with tree roots such as Pine trees or Quercus trees.

Earthstars are often found on a little cut slope along a forest road rather than inside a forest. Why it happens is not well understood. However, I think that young mushroom can easily emerge out of the underground in the case of a slope, and we can also easily find out them.

The earthstar mushrooms are often growing on the slope along a forest road like this.

This September, I went to observe the earthstar mushroom in the forest where I found this mushroom last year. At this place, there are big pine and oak trees which earthstar mushroom can live with symbiotically. I found several brown puffball mushrooms that emerged out of the ground by half. At that time, I didn't understand what it was. But I thought they might be young earthstar mushrooms prior to splitting outer shell, so I brought them home.

These are the ball shaped mushrooms I brought from the forest.

I thought that if they were the young earthstar mushrooms, they would open up into a star shape if I kept them moistened, so I put them in a glass bottle with a wet kitchen paper towel.

I repeated wet and dry condition in a glass bottle for 12 days. At last, the outer shell of ball-like mushrooms has splitted into a star-like shape.

As I expected this ball-shaped fungus was the earthstar mushroom.

Next topics is the inner structure of this mushroom and its spores. This is the earthstar mushroom that I found at the same forest mentioned earlier in this December. 

I found an earthstar mushroom whose spore bag had not yet opened a center hole, so I took it home.

When I cut the spore bag with a utility knife, I found that it was full of spores as I expected. 

I lined up the cross sections.

I dropped some spores onto an agar plate. They look just like cocoa powder.

I observed the spores at 400x magnification using a small, handheld microscope. Unlike the high-grade microscopes provided at universities and agricultural research centers, I couldn't take sharp photos because this microscope didn't equip with a condenser or anything like that, but according to Wikipedia (English version), they are round spores about 7 to 11 micrometers (about 1/100 millimeter) in diameter.

One more other topic on this mushroom. When I saw the mushroom whose spore bag was torn, and spores were scattered around the bag, I noticed that small, round lumps had appeared in the spore mass. I wonder what this is. 

Magnified photo.

It looked like this. It looked a bit like a balloon.　

I tried examining this sphere, I poked a small one with a tip of a chopstick while looking at it through a magnifying glass, then it disappeared in an instant.

I think this sphere is a raindrop and fungal spores are stick to the outer surface of a raindrop. In general, fungal spores are hydrophobic and do not mix well with water, so I think this is why it ended up like this. In fact, it rained yesterday.