Paragyrodon sphaerosporus is one of the boletes, which are distinguished by their producing mushroom-like fruiting bodies with pores on the underside instead of gills or teeth. If you've been reading my pages, you'll remember that the other group of pored fungi are the polypores. I think we'll first review (or tell you for the first time) "What is a bolete?"

Boletes are a group of mostly mycorrhizal, mushroom shaped fungi, distinguished by their pores. Like gills, these pores are lined with basidia that produce basidiospores, serving to increase the surface area. These are distinguished from the other major group of pored fungi, the polypores, by several different characteristics, as shown in this table:

	Boletes	Polypores
Pore layer	Peels off	Does not peel off
Nutrition	Mycorrhizal, i.e. with a mutualistic association with roots of trees	Wood decay
Fruiting location	Typically on the ground, fruiting from the roots of trees	Typically directly on wood, although may be on the ground from buried wood.
Shape	Typically mushroom shaped	Typically in the form of a shelf or some other shape

So you can see it's usually easy to distinguish between boletes and polypores, although there are a few that will give you trouble by breaking the rules. For example, members of the genus Albatrellus are considered to be polypores because their pores don't peel, even though they are mycorrhizal. Polyporus radicatus and several related polypores without peeling pores almost always grow on the ground, but if you dig down, you can almost always find the piece of buried wood from which the fungus is fruiting. There are also a few boletes, like Boletus mirabilis that climb up on logs to fruit, raising themselves up to get their spores further into the air stream. In fact some mycologists argue that some of these boletes may not be mycorrhizal after all. Fortunately, most boletes and polypores have read the books and follow the rules.

So now you should know how to tell the difference between boletes and polypores. But what of our oddball Paragyrodon sphaerosporus ? Paragyrodon sphaerosporus (Peck) Singer used to be known as Suillus sphaerosporus (Peck) Smith & Thiers, but it is rather different from other boletes such as Boletus edulis, Boletus barrowsii, Gyroporus cyanescens, and Suillus americanus.

One major difference is the shape of the spores. Most boletes have cylindrical shaped brown basidiospores, which means that they are elongated and flattened on the sides, kind of like a can of spray paint. P. sphaerosporus spores are --- well --- spherical. Of course that's where the specific term comes from. Basidiospore characteristics play a major role in distinguishing between genera of fungi, with a different shape usually indicating a different genus. Within a single genus, usually the shape of the basidiospores is the same, but the spores differ in size between the species in that genus. There are, of course, exceptions to this rule, but we'll leave those for another day.

P. sphaerosporus is also different because of its leathery partial veil that covers the pores to protect them as they are developing. As the fruiting body enlarges as the cells of the cap inflate, the force of the expansion ruptures the veil, as shown to the right. By then the basidiospores are mature and can be released to the environment, where they can potentially produce more of the species. There are some other species of boletes that have a partial veil, but none so tough and leathery as Paragyrodon. For example, some Suillus species have a partial veil; this is one of the reasons our Paragyrodon was once called Suillus sphaerosporus. However, Suillus veils tend to be rather slimy, not leathery. Also, the veil of Paragyrodon is attached almost at the base of the stem, so that the immature mushroom is almost shaped like a toy top. Another big difference is that all Suillus species (so far as I know) are mycorrhizal with members of the Pinaceae, especially pines (Pinus spp.). P. sphaerosporus is always mycorrhizal with oak (Quercusspp.), not pine. There are, of course, many other genera of fungi whose members are mycorrhizal with oaks.

Any one of these characteristics is probably not enough to merit construction of new genus, but these major differences indicate that Paragyrodon sphaerosporus does not belong in any other bolete genus. This is why Rolf Singer created the genus Paragyrodon in 1942. In many ways, Singer was far ahead of his time, with a large percentage of his distinctions corroborated by molecular biology techniques, like PCR and DNA sequencing.

Of course, the big question is, "Is it edible?" It's very tempting to eat it because they can be a big mushrooms (20 cm or more across the cap) and is sometimes locally abundant. Well we don't know that for sure because there has been no rigorous scientific testing. However there are anecdotal reports from various people have tried it and survived without ill effects. You're on your own on this one.

For more of the details on the anatomy and history of Paragyrodon sphaerosporus, you can visit Michael Kuo's P. sphaerosporus page at MushroomExpert.com.

I hope you enjoyed learning about the very unusual leathery-veiled bolete Paragyrodon sphaerosporus. It's not very common, but when you find this species there are usually many fruiting bodies. Good luck on your hunting!

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