Further to earlier thread about Collared Earthstar Geastrum triplex

[CloudedYellow]

I took the attached today in Nottinghamshire. I believe it is a Geastrum triplex because it was with four others, all with typical collars. This one however lacks a collar and had a smaller spore sac - just under 2cm across whilst the other four where 3-3.5cm across.

Thoughts please




CY

[GerryNick2]

Hi CY

The plot thickens as they say.

From what can be observed from the photograph I am pretty certain you are correct in your assumption that this is G. triplex. The radials of the outer wall are showing signs of splitting crosswise which as the fungi matures will fold under creating in the process the more familiar saucer shape common to G.triplex. There appears to be a paler ring or depression around the raised apical pore which is also characteristic of G.triplex and not usually observed on G.fimbriatum.

Gerry

[CloudedYellow]

Originally Posted by GerryNick2

Hi CY

From what can be observed from the photograph I am pretty certain you are correct in your assumption that this is G. triplex.

Gerry

Thank you Gerry,

Richard aka CY

[cybershot]

Courtesy of Santa Claus I am now in possession of Roger Phillips' Mushrooms book and after reference thereto I have to agree with Gerry (having at first bowled me a googly regarding G. fimbriatum!) that CY's specimen above and those featured in my earlier thread are all G. triplex - Collared Earthstar. It seems evident now that the saucer-like base is created with the cracking of the rays when they bend back under, and is not, as I first imagined, a separate distinct element distinguishing G. triplex.

[CloudedYellow]

Originally Posted by cybershot

It seems evident now that the saucer-like base is created with the cracking of the rays when they bend back under, and is not, as I first imagined, a separate distinct element distinguishing G. triplex.

I am sure you are right, hopefully the above will be undisturbed when I go back tomorrow or Sunday to see how it has changed.

[GerryNick2]

Originally Posted by cybershot

Courtesy of Santa Claus I am now in possession of Roger Phillips' Mushrooms book and after reference thereto I have to agree with Gerry (having at first bowled me a googly regarding G. fimbriatum!) that CY's specimen above and those featured in my earlier thread are all G. triplex - Collared Earthstar. It seems evident now that the saucer-like base is created with the cracking of the rays when they bend back under, and is not, as I first imagined, a separate distinct element distinguishing G. triplex.

Hi David

Apologies for the confusion caused, after further study on the subject of Geastrum Sp. can concur the image you posted is without doubt G.triplex.

Gerry

[cybershot]

Originally Posted by GerryNick2

Hi David

Apologies for the confusion caused, after further study on the subject of Geastrum Sp. can concur the image you posted is without doubt G.triplex.

Gerry

No problem Gerry; when it comes down to ID on macroscopic comparisons of physical characteristics nothing surprises me any more and your initial observations made complete sense under the circumstances surrounding my own inspections and investigations: Even now, armed with the indisputable evidence of Phillips, I still find it hard to believe that my find included only one species in the colony comparing the deceptive attributes of size, colour and nature of the rays at different states of maturity. I suppose the defining factor being the paler ring around the slightly raised mouth of the spore sac evident on all the specimens. What exactly constitutes a 'collar' at the various stages of development seems a less conclusive argument concerned only with the suitability of a common name.

I have enjoyed this, my first, season and appreciate all the help gleaned from this site.

Best regards and Happy New year

David

[CloudedYellow]

Been back to see it today: the apical pore has now opened (maybe due to overnight rain?), there is still a ring around it but there is definitely no sign of a collar - even if the rays were to break off I cannot imagine that a collar would form. I was again struck by the noticeably smaller size.

Is anyone aware of any microscopic differences between fimbriatum and triplex?

Jordan describes the spores of fimbriatum as 'finely spiny and sub-spherical' and triplex as 'warty and spherical' whilst Phillips describes them both as being 'globose' with the former being 'minutely warted' and the latter 'warted'. Both suggest that fimbriatum spores are slightly smaller.

I just looked at spores taken from the above and from an obvious Collared Earthstar - they look the same to me (no surprise there!)

[GerryNick2]

Hi CY

You are right in your assumptions 'size does matter.' the spores in both species are described as being round and warted and of different shades of dark to chocolate brown. Spores of G.fimbriatum are 2.9-3.5 microns G.triplex 3.5-4.5 microns. To detect this you would obviously need a high powered microscope with an accurate calibration scale.

There seems to be a great deal of variation in the extent to which the fleshy upper surface of the rays crack in G.triplex. It is not at all unusual to find some that don't crack at all and thereby are easily confused with G.fimbriatum.

G.fimbriatum is a smaller species both in overall dimensions and the spore sac. Rightly or wrongly I tend use the key feature of the circle around the apical pore to distinguish the two.The best description I have is taken from an american publication " G.fimbriatum (=G.sessile), often slightly darker, with a torn fringed apical pore that is not set off by a circle"

Hope this of some help in your deliberations.

Gerry

[CloudedYellow]

Certainly does. Thank you.

Richard aka CY