The Beaked Earthstar, Geastrum pectinatum?

[John R]

Thank you to Mike Cruse for leading us to this fine earthstar.

The macro characteristics fitted with those reported for G.pectinatum (small vertical lines underneath the spore sac and a small collar below stem plus the “beaked” apical pore). Wikipedia entry

Spores were spherical with small warts. Spore size was 4.6 – 4.7 um (excluding warts). Fits with FoS.

Size and characteristics of fruit body also seem to fit – except – ours only has 5 pointed rays on base rather than the reported:

7-8 FoS
6-9 Buczacki
6-12 Philips

If anybody has any thoughts or an alternative please let me know.

Cheers,

John

[Doug]

John according to the Kew book unless it has a collar at the base of the globular structure it must be G. pectinatum. If it has a collar it should be G striatum

[Tom Kirby]

Yes. From the pic it looks like G.striatum. There should be pronounced lines (striations) beneath the collar.
Best,
Tom

[John R]

Thanks Doug – I don’t have access to the Kew book unfortunately.

Below is a close up of under the spore sac.

The wikipedia entry for G. pectinatum (admittedly possibly not the most reliable source of information) says

“The tough and membranous endoperidium comprising the spore sac, purple-brown in color and 0.5 to 1.5 cm (0.2 to 0.6 in) tall by 1 to 2.5 cm (0.4 to 1.0 in) wide, is supported by a small stalk—a pedicel—that is 3–4 mm long by 7–10 mm wide and which has a grooved (sulcate) apophysis, or swelling. This ring-shaped swelling is made of remnants from a tissue called the pseudoparenchymatous layer.[16] When fresh, the pseudoparenchymatous layer is whitish in color, thick and fleshy; it dries to become brown to dark brown while shrinking and often splitting and peeling.[13] “

[John R]

Measurements fit with G. pectinatum as far as I can tell. Endoperidium diameter 1.4 cm (not shown).

[John R]

Some good images of G.striatum here showing a wide collar under the spore sac

http://www.hlasek.com/geastrum_striatum.html

[Doug]

That must be the thickened ring like zone rather than a collar which is well illustrated in the attached photos. So G. pectinatum looks good to me.

[Tom Kirby]

….except, of course, I am completely incorrect (and this from the man who appeared on TV with a whole host of G.striatum…and who converted his kitchen in to a photographic studio so that Paul Foster could photograph said species in minutiae). The striations are ABOVE the collar.
Tom

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