Geastrum triplex

Today we feature the fungus Geastrum triplex, commonly known as the saucered or collared earthstar. These images (image 1 | image 2) were taken recently at the State Botanical Garden of Georgia and uploaded to the Botany Photo of the Day Flickr Pool by Hugh Nourse (aka Hugh and Carol Nourse@Flickr). Thanks for sharing, Hugh!

Geastrum triplex, of the Geastraceae, is an earthstar fungus. The earthstars are comprised of the genera Geastrum, Astraeus, and Myriostoma. Earthstars are modified puffballs that have a thick outer skin that splits into star-like rays (Geastrum saccatum was featured on Botany Photo of the Day in 2011). The rays, after splitting, often curve to expose the spore case (inner skin) for spore dispersal. Some earthstars are hygroscopic, though, most geastrums (including Geastrum triplex) are not. After the rays split, the central region of Geastrum triplex often (not always) breaks loose to form a broad cup or saucer around the flattened spore case. The spore case of the saucered earthstar is not elevated on a stalk (like others in the genus), and holds powdery, brown spores that are round and warted.

Geastrum triplex is a saprobic (feeding on dead or decaying matter) fungus that is widely distributed across North America. It grows alone or in groups in forest humus, often under hardwood trees. This species (like all earthstars) is noted to be difficult to find when immature because individuals are inconspicuous, and often develop underground. If you do happen to find this fungus when it is young (white inside), it is considered edible according to Mushrooms Demystified by David Arora. When they are older (and easier to find), they are apparently often too tough and fibrous to eat.

Geastrum triplex
Geastrum triplex

9 responses to “Geastrum triplex”

  1. Knox M. Henry

    Very interesting and intriguing. If the spores are within the flattened spore case, how do they disperse?

  2. Dianne Saichek

    How big are these? I don’t see anything I can recognize in the pictures to grok their size. Help!!

  3. Taisha

    Knox, the spores are held within the spore case. When the spore case is under pressure it releases the spores via an apical pore, much like puffballs. After the spores are released, they are dispersed by wind or water. Check out this great YouTube video clip from BBC’s “The Private Life of Plants”.
    Dianne, The fruiting body of Geastrum triplex can be 3-10cm broad, and the spore case 1-3cm wide.

  4. Hugh Nourse

    I am somewhat humbled because some who have seen this picture question my identification because it does not look like any of the photos on line with this name. We are currently trying to get a mushroom expert to verify its identification.

  5. Bonnie

    Your fungi photos are the best! This puffball looks like it comes from another planet. Probably not Mars, though.

  6. Sara

    CAKE! with ice cream!
    Lady fingers/cake/ice cream on top!!!
    What do you mean it’s a mushroom?
    Beautiful photo. If this little beauty is only 3 cm (less than an inch) then I can see why it is easily missed.

  7. Julie Gorka

    What a great-looking little fungus! Here in North Carolina I get some earth stars in my garden, but I don’t see them until they are plain, brown, and flat, just as mentioned. I don’t know if they are the same kind as the ones in the photos, but now I’m curious and will watch more carefully.
    Thanks for the interesting post!

  8. Kris

    Sara, that was my first thought, too. 🙂
    Great pictures!

  9. Hugh Nourse

    One of the mushroom experts has viewed the photos, and has replied that the identification is correct.

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