Please do not re-click a link while waiting for a page to load. (It’s slower and degrades site speed for all users.)
To get images for machine learning, see MO Images for Machine Learning


Original Herbarium Label: Arrhenia acerosa f. latispora Favre
Identified from the MO posting by Dr. R. Greg Thorn – 2016-12-01
Growing on Dicranum scoparium

Species Lists


Gill margin
Gill margin
Gill margin + ?cystidium
Spores 7-8 × 5-7 µm
Spores 7-8 × 5-7 µm with cotton blue

Proposed Names

-21% (2)
Used references: MycoBank current name
87% (1)
Used references: On Dec. 1, 2016 Dr. R. Greg Thorn wrote:
“Quite likely then you have the ‘var. latispora’, although Funga Nordica does not recognize it as distinct. They give the spores as (5-)6-9.5(-11) x (3-)4-6.5(-7), subglobose, … Definitely not Hohenbuehelia.”

Please login to propose your own names and vote on existing names.

= Observer’s choice
= Current consensus


Add Comment
Dyes and other reagents
By: Rocky Houghtby
2016-12-07 10:56:41 CST (-0500)

Cause the cells of the specimen to deform, and sometimes rupture. Water is isotonic, and will generally provide the best medium for accurate measurements. However, if the measurements of a type description were performed using a specific solution, the same solution should be used when comparing your collection, at the very least in addition to measurements made in water.

Oluna’s microscopy and documentation are world class.

Apologies for our Czechlish
By: Oluna & Adolf Ceska (
2016-12-07 10:35:49 CST (-0500)

You put the piece of a gill flat on the slide with the gill edge facing you. In the microscope you will see the edge being up. Oluna insists on doing all the measurements in water without any dye.
Adolf (Oluna’s audio mouse)

Thanks Oluna. Amen to all of that.
By: Martin Livezey (MLivezey)
2016-12-07 07:22:13 CST (-0500)

…especially the part about not often finding basidia with spores attached…and not finding whole cystidia to measure. I don’t quite understand why the gill edge would be down (pointing away from the objective) if it is the gill edge we are examining, but maybe I mis-interpret your suggestion. Gill edge down might be useful for examining the side of the gill, right? In either case, I will try following your instructions exactly. It is not a big change from what I am doing. I almost always use red dye to stain. I just got a version of cotton blue from Anna Gerenday

Preparation of the slide
By: Oluna & Adolf Ceska (
2016-12-06 21:49:15 CST (-0500)

is not difficult. With the fine-pointed tweezers and under the dissecting scope, select a single gill and tear a piece of it off. Transfer it into a very small drop of water on the slide. Under the dissecting scope, rearrange the piece of the gill in such a way that the edge of the gill is down. If it is still floating, either remove some of the water or push the piece of the to the margin of the drop. Make sure it is not moving, when it is on the slide. Place the cover slip carefully on the top of it, tap it very lightly with a finger or a pencil eraser to remove bubbles. Add carefully water from the edge of the slide to saturate it, but not too much. Use empty eye drop bottles for water (not large pipettes!), they work the best. You can add the water when it starts drying up from the edge of the cover slip.. In order to see/measure the whole basidia or cystidia, you have to squash it more. I do all the measurements in water. I add the Melzer, cotton blue, household ammonia (instead of KOH) to the slide after I do the measurements.
I use water instead of immersion oil only for spores smaller than 5 µm. Adolf takes spore photos with 60x objective and a handheld camera set to the edge of the optical zoom. Let me know if you have any problems. Good luck. Oluna
P.S. Not often you will get basidia with all the spores attached.

I have no suggestion of ID
By: Martin Livezey (MLivezey)
2016-12-06 06:16:40 CST (-0500)

but I do of the microscopy technique. I know you use water instead of immersion oil between the objective and the cover slip. You appear not to think much of the use of dye – cotton blue below is the one of the first use of dye by you that I remember. The photo of the basidium is particularly interesting, and one that I have not been able to reproduce in most of my attempts. Did you section the gill with a razor? Do you press on the cover slip or simply let it float?

I wish you were right!
By: Oluna & Adolf Ceska (
2016-12-01 16:13:14 CST (-0500)

I am just corresponding with Dr. Greg Thorn who is questioning our identification.
P.S. Martin Livezey’s comment refers to the myxomop’s wrong identification when he called this MO observation Hohenbuehelia tremula (Schaeff.) Thorn & G.L. Barron.
P.P.S. The Achilles Heel of MO “naming” is that any MO user can change other MO users’ names by crossing out the original ID and “deprecating” it. IF YOU HAVE ANY SUGGESTION OF A DIFFERENT ID, please, MAKE IT AS A COMMENT, not by changing the original name.

Beautiful observation! Thank you.
By: Martin Livezey (MLivezey)
2016-12-01 16:05:59 CST (-0500)

First observation of this species on MO!