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18-06-2019 16:55

Chris Yeates Chris Yeates

Bonjour tous a recent collection of damp leaves o

17-06-2019 16:18

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A small group of Perithecia on rotten (salix?) woo

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tiny discomycete on Glyceria
Chris Yeates, 18-06-2019 16:55
Chris Yeates
Bonjour tous

a recent collection of damp leaves of Glyceria maxima has numerous, generally rather scattered, pale sessile ascomata.

The margins are "fringed" rather than hairy, and under the microscope can be seen as projecting marginal cells, a considerable number of which are swollen up to 4.6µm and contain vacuolar material (hyaline >possibly very pale straw colour).

Asci 30.3-39 x 4.9-5.9µm; "Psilachnum guttules" not seen; although difficult to see I think there were croziers (see image); apex blue in Lugol's.

Ascospores mostly staight, narrowly clavate, with a few small mostly polar guttules, 7.2-8.7 x 4.8-5.7µm.

I think this is Psilachnum eburneum (Pezizella eburnea). The absence of a guttule in the asci may well be due to stage of development. Dennis in CMI Mycological Paper 62 (1956) makes no mention of the vacuolar content at the hair apices, but I suspect this was due to him working from dried material (this v. content disppeared when Lugol was added to the mount). An image of Stip's seems to show similar content in the apical cell: http://www.helotiales.nl/english/Species/Psilachnum_eburneum.htm

Any comments welcome

Merci

Chris
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Hans-Otto Baral, 18-06-2019 18:04
Hans-Otto Baral
Re : tiny discomycete on Glyceria
Hi Chris
Dennis almost never reported any VBs in the paraphyses or hairs. And yes, it is surely a Psilachnum and probably P. eburneum from my memory. P. acutum has more lanceolate, far protruding paraphyses.
Zotto
Chris Yeates, 18-06-2019 19:53
Chris Yeates
Re : tiny discomycete on Glyceria
Many thanks as ever Zotto,

I didn't post an image of the paraphyses, I realise. But they were narrow and non-protruding.

LG

Chris
Hans-Otto Baral, 18-06-2019 20:50
Hans-Otto Baral
Re : tiny discomycete on Glyceria
Ah they were all hairs. I remember hairs and paraphyses +/- cylindrical in eburneum, but in chrysostigma they also vary between cyl. and sublanceolate.
Stip Helleman, 18-06-2019 22:27
Stip Helleman
Re : tiny discomycete on Glyceria
P. lateritio-album has lanceolate hairs with VBs but they seem considerably longer (at least in my collection a few weeks ago) but your Frbs. looks younger.

cheers,

Stip
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Hans-Otto Baral, 19-06-2019 09:28
Hans-Otto Baral
Re : tiny discomycete on Glyceria
Yes, this is similar but hairs longer and also paraphyses strongly protruding.