| Major Groups > Puffballs & Others > Geastrum saccatum |
|
Geastrum saccatum [ Basidiomycetes > Phallales > Geastraceae > Geastrum . . . ] by Ron Meyers It is surprising that so common a mushroom as Geastrum saccatum seems to lack an accepted common name. It is referred to as the "Common Earthstar," the "Sessile Earthstar," and the "Rounded Earthstar," depending on whose field guide you are consulting. Our Kansas book uses "Common Earthstar," which is appropriate because while we do occasionally find other earthstars here, Geastrum saccatum is by far the most prevalent. Although this mushroom fruits from spring to fall, its muted color and small stature make it easy to overlook, particularly if it is partly covered with leaf litter. But if you do spot one, you will usually find that there are several in the immediate area. My most notable earthstar finding was a strangely shaped “egg” which somewhat resembled a rubber ear syringe (familiar to parents of young children). I was able to “hatch” it in a pot of moist soil and was rewarded with a fresh earthstar. The method of spore dispersal is similar to many puffballs. Spores are ejected through the apical pore by rain drops hitting the spore case or even by wind blowing across the pore. Description: Ecology: Saprobic; growing alone or in groups under both conifers and hardwoods, in humus or leaf litter; normally reported from summer to fall, but we have several spring findings in Kansas. Fruiting Body: 0.5-1.5 cm broad when unopened; partially buried; round; somewhat flattened, with a pointed apex. In maturity the outer wall splits to form 4-9 rays which spread, become star-shaped, and then recurve back under the fruiting body; 2-5 cm broad when opened. Spore case 0.5-2 cm broad; round; paper thin; white becoming grayish brown or brown; stemless; with an apical pore surrounded by a circular groove or halo and a paler area. Rays or arms pink to brown; rubbery when fresh; sometimes cracking when dry; upright at first; later curving back and under. Spore mass white and firm, becoming purple brown and powdery at maturity. Immature Fruiting Body: Like a whitish to yellowish or purplish (see comments below) "egg" up to 6 cm high; when sliced revealing the stinkhorn-to-be encased in a gelatinous substance. Microscopic Features: Spores 3.5 x 5 µ; round; warted; brown. REFERENCES: Fries, 1829. (Smith, 1951; Ramsey, 1978 / 2003; Smith, Smith & Weber, 1981; Arora, 1986; Phillips, 1991/2005; Lincoff, 1992; Metzler & Metzler, 1992; Horn, Kay, and Abel, 1993; Barron, 1999.) Geastrum fimbriatum is a very similar mushroom, but Geastrum saccatum has a more well defined halo. From studying the excellent photograph in Roody's Mushrooms of West Virginia and the Central Appalachians (2003), I believe I would have great difficulty discerning between the two. Astraeus hygrometricus is another earthstar which resembles Geastrum saccatum and used to be placed in Geastrum until separated out by a Cincinnati high school biology teacher, Andrew P. Morgan, for some very technical reasons. Its most distinguishing characteristic is its unique rays, which close under dry conditions and open when rain hits them. Now a paper, "Toward a Global Phylogeny of the Boletales," (Halling, Binder, and Hibbett) reports DNA evidence that the two mushrooms are not even in the same family; Astraeus belongs in the order Boletales, and is closely related to Scleroderma, the false puffballs. Other molecular studies indicate that Geastrum may be more closely related to the stinkhorns, the coral fungus, and the cannonball fungus, than to puffballs like Lycoperdon or Calvatia species. Further Online Information: Geastrum saccatum at MykoWeb |
© MushroomExpert.Com |
|
Cite this page as: Meyers, R. (2004, April). Geastrum saccatum. Retrieved from the MushroomExpert.Com Web site: http://www.mushroomexpert.com/geastrum_saccatum.html |