These species are covered in three keys: the puffballs and earthstars in the Key to Lycoperdaceae and Geastraceae, the earthballs in the Key to Sclerodermataceae, and the stalked puffballs in Woody Desert Fungi.
The Key to LYCOPERDACEAE and GEASTRACEAE covers the puffball genera Bovista, Calbovista, Calvatia, Disciseda, Lycoperdon, Mycenastrum, Myriostoma, Vascellum, the earthstar genus Geastrum, and for convenience the earthstar genus Astraeus. Sphaerobolus, the cannon-ball fungus, is presently in Geastraceae, but it is considered instead under BIRD'S NEST FUNGI. Earthstars have two layers to the spore case, of which the outer splits in star-like fashion to expose the inner layer. The star-like limbs can curl back to act like feet, sometimes doing so only in wet weather and closing again when weather is dry.
The SCLERODERMATACEAE key covers Scleroderma, Astraeus, and Pisolithus.Earthballs (Scleroderma) differ from puffballs in having a thicker, hard to tough outer rind, and when the spore mass becomes dark, it remains firm rather than becoming soft. There is no sterile base.
The WOODY DESERT FUNGI key discusses stalked puffballs (Tulostoma, Battarrea, Chlamydopus, and Phellorinia). The original Tulostoma key only considers 10 species. More than 30 Tulostoma species are now documented from the Pacific Northwest: these species are listed, but the Tulostoma key needs revision.
These groups have in common that they do not forcibly discharge their spores. The spore mass develops inside the fruitbody and becomes powdery with maturity. After rupture, the wind is able to blow the spores to other locations.
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