This months featured images explore the world of the fungus.
Mushrooms and Toadstools, in fact many sorts of fungus, are visible in the fall particularly after a period of wet weather. To the unaided eye the typical toadstools appear in a wide variety of different shapes and colors; tall and thin like the Ink caps on the left, or squat and wide like the Honey Mushroom on the right.
There are many ways to tell the different types of mushroom apart. The shape, size and color are obvious clues, but may not be sufficient to correctly identify the mushroom. Since there are both poisonous mushrooms, and mushrooms that are very tasty and edible, it can be very important to be able to correctly identify a mushroom. There are many features that we can use to identify different fungi, apart from the shape, size or color of the cap. Other useful clues include where it is growing and on what; some fungi have an association with a particular species of tree for example, others grow in meadows. Different fungi fruit at different times of the year, which can also help with the identification. Many differences can more easily be seen with the aid of a microscope.
Underneath the cap most mushrooms have an array of Gills like those shown on the left. These radiate from the position where the cap is attached to the stalk of the mushroom. In some mushrooms the gills are separate from the stalk. Some others have attached gills, or gills which are not attached all the way. This can also be a clue to identification. Other groups of mushrooms do not have gills at all. The bracket fungus and the Turkey-Tail fungus (which are both found on trees) have pores underneath their caps. So do a family of fairly large mushrooms called the Boletes, one of which is shown here on the right. The gills and the pores both give the fungus a very large surface area from where it can release a very large number of spores. These spores are the mushroom equivalent of the seeds of a plant. They travel on the wind, and if they find a suitable site they will be able to start growing into a new mushroom.
Since the spores are very small - about 10 can fit end-to-end across the width of a human hair - they can be seen best in a Scanning electron microscope. The images seen there do not show the color of the spores, but the surface texture. On the left are some spores from one gill of the Honey Mushroom. This complete image is less than the width of one hair, and there are about 100 spores here. So for the whole gill there would be 5-10 million spores. Each Mushroom has more than a hundred gills, so they can produce an enormous number of spores. If they all found a good site to grow in then we would very quickly be covered in mushrooms.
The other image is of a Turkey-tail fungus which appears on dead trees. It does not have gills but produces spores on the inside of its pores. This pore is quite old and has released all of its spores.
Below are three more SEM images from the Turkey tail fungus. We have cut the fungus in half where it is connected to the tree to see how it is attached. In the first two images the sloping lines to the right of the image are walls in the structure of the tree. The spongier mass to the left is the meat of the fungus. It is composed of lots of individual threads or hyphae, which also extend into the wood. The third image shows a higher magnification of the root-like hyphae running through the wood.
All of these were found in a couple of mushrooms. Just imagine what other mysterious things we might have found on different mushrooms. Better yet, next time you find a mushroom, cut off the stalk and put the cap cap-side-up on a piece of paper. After a couple of hours you will have a spore print (it helps to cover the mushroom to keep any drafts from blowing the tiny spores around as they fall from the mushroom to the paper). See what color they are, count how many gills the mushroom has. Find a mushroom book and try to identify it.
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Last Update: 10/28/96