Public Description of Geastrum saccatum Fr.

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Name: Geastrum saccatum Fr.
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Description status: Unreviewed

Taxonomic Classification:

Domain: Eukarya
Kingdom: Fungi
Phylum: Basidiomycota
Class: Agaricomycetes
Order: Geastrales
Family: Geastraceae

Diagnostic Description:

From Ponce. (1968) (public domain):

Unexpanded basidiocarp ovate with a point up to 4 mm. long, or with a
rounded umbo, half-exposed or superficial, 2-3 cm. wide, 3 cm. high,
with the mycelium attached to a basal point, becoming expanded when 3
cm. wide; exoperidium split to about the middle into 5-9 pliable,
thin, expanded or revolute, equal, acute rays, leaving the base
saccate; when open, the rays can attain a width of 1-2 cm.; fleshy
layer brown, adnate, frequently rimose; outer layer ochraceous buff or
cinnamon buff, spongy-felted, with very little adhering debris; when
dried, irregularly rimose or pulling off over considerable areas; with
a prominent umbilical scar in the middle of the base where the
mycelium was attached; endoperidium sessile, 0.5-2 cm. in diameter,
globose, glabrous, brown, partially enclosed by the saccate base of
the exoperidium; peristome conic, fibrillose, delimited by a circular,
raised or depressed line, silky, paler or more brownish than the
spore-case wall; gleba umber or paler; columella indistinct, or a
pseudocolumella present; spores globose, 3.4um in diameter, globose,
verrucose, with hyaline or yellowish warts (there are many
poorly-formed spores in mounts); capillitium 4um, pale yellowish to
brownish, very thick-walled, tapering, undulate, often cracked, some
threads having ramifications at the ends, 4um diameter, incrusted with
much debris.




Solitary or in small groups, sometimes gregarious, on rich humus,
often around old stumps; epigaean.

Look Alikes:

This species has been confused with G. fimbriatum in many herbaria as
they have the same exterior aspect and are of equal size and
shape. However, the mouth of G. saccatum is surrounded by a silky
peristome limited by a groove, the button is pointed and free of
debris, and presents a definite scar in the lower part where the
mycelia was attached. Further, the spores of G. saccatum are more
rugose and the capillitium is wider.

Geastrum saccatum differs from G. indicum only in size, the latter
being usually larger. The smallest forms of G. indicum and those of
lageniform habit in the two species are difficult to separate. The
presence of spores of different size and of abundant debris in the
gleba of G. saccatus also help to separate these two species.


Geastrum saccatum (Fr.) Fischer, Nat. Pflanz. 2(7) : 73. 1933.
Geastrum saccatum var. cinereum Stanek, Fl. CSR, B-l: 493. 1958.
G. saccatum var. wichanskyi Stanek, Fl. CSR. B-l : 494. 1958.
Geaster saccatus Fr. Syst. Myc. 3: 16. 1829.

Description author: Joseph D. Cohen (Request Authorship Credit)
Description editor: La Monte Henry Piggy Yarroll

Created: 2009-12-12 17:36:58 CET (+0100) by La Monte Henry Piggy Yarroll (piggy)
Last modified: 2013-11-30 20:37:55 CET (+0100) by Joseph D. Cohen (Joe Cohen)
Viewed: 203 times, last viewed: 2018-11-20 11:40:23 CET (+0100)