Search found 47 matches

by Mark Powell
Mon Mar 16, 2020 9:56 pm
Forum: Lichens
Topic: K/UV reaction
Replies: 9
Views: 1423

Re: K/UV reaction

When you click on my twitter link (previous post), you will need to scroll down the thread to see the scans of the Bulletin article detailing the K/UV reactions.
by Mark Powell
Mon Mar 16, 2020 9:54 pm
Forum: Lichens
Topic: K/UV reaction
Replies: 9
Views: 1423

Re: K/UV reaction

I wrote a fair summary in the Bulletin and scans of this have been posted on my twitter: https://twitter.com/obfuscans3/status/1207602169828069376 If you need further information, then do let me know. So far, it is still the atranorin and confluentic acid tests that have proved potentially useful (t...
by Mark Powell
Tue Feb 11, 2020 10:52 am
Forum: Lichens
Topic: A problematic Parmelia
Replies: 13
Views: 1881

Re: A problematic Parmelia

I wholeheartedly agree with the tone of Chris and Neil's replies. If anyone has any genuine queries then we can all learn from having them posted on this forum. There are two aspects in particular that I like about airing queries in public. First is the way that so many others can learn from the dis...
by Mark Powell
Mon Feb 10, 2020 5:58 pm
Forum: Lichens
Topic: A problematic Parmelia
Replies: 13
Views: 1881

Re: A problematic Parmelia

It could be a chemical var. without usnic acid but perhaps more likely to be an individual in which the usnic acid colour is less apparent. Perhaps specimens growing in shade (or other environmental factors) leads to them having lower concentration of usnic acid. I have a nice specimen of X. tinctin...
by Mark Powell
Mon Feb 10, 2020 5:02 pm
Forum: Lichens
Topic: A problematic Parmelia
Replies: 13
Views: 1881

Re: A problematic Parmelia

I am going to throw another suggestion into the mix, not a definite identification at this stage. What about Xanthoparmelia conspersa ? Although I would expect X. conspersa to be a yellow-green colour, that does depend on the specimen and the lighting. Mark, when viewed in daylight, does the thallus...
by Mark Powell
Mon Jan 13, 2020 1:22 pm
Forum: Lichens
Topic: Hairy Jelly
Replies: 7
Views: 1330

Re: Hairy Jelly

I tried to key out Juliet's lichen with the new Collemataceae key, assuming that we have decided that it doesn't have any true 'tomentum' and arrived at couplet 40 where we are asked whether it is a) On calcareous soil, brick or mortar b) On rocks or amongst mosses on rocks Scytinium turgidum and S....
by Mark Powell
Mon Jan 13, 2020 12:48 pm
Forum: Lichens
Topic: Hairy Jelly
Replies: 7
Views: 1330

Re: Hairy Jelly

The draft definition of tomentum for LGBI3 has been slightly expanded and is currently as follows: tomentum (-ose), felt-like mat of hyphae; a special case of pubescence in which the soft hairs are matted and usually pressed close to the surface. For reference: pubescent , having soft, short hairs (...
by Mark Powell
Mon Jan 13, 2020 12:58 am
Forum: Lichens
Topic: Hairy Jelly
Replies: 7
Views: 1330

Re: Hairy Jelly

Before I give my opinion on the identity, I am repeatedly disappointed by dichotomous keys. In my experience they are the cause of numerous misidentifications and misunderstandings. Whether they are a necessary evil, I'm not sure. For the moment they are the practical reality so we have to learn how...
by Mark Powell
Wed Jan 01, 2020 8:40 pm
Forum: Lichens
Topic: Xanthoria parietina is C+ red
Replies: 3
Views: 739

Re: Xanthoria parietina is C+ red

I think that I have demonstrated Jack Laundon's C+ reaction in the apothecia of Caloplaca albolutescens (probably identical in this sense to C. teicholyta which he mentions, and he may not have distinguished between them at that time). I will post the extract from Jack's paper, then the apothecial m...
by Mark Powell
Wed Jan 01, 2020 8:33 pm
Forum: Lichens
Topic: Xanthoria parietina is C+ red
Replies: 3
Views: 739

Re: Xanthoria parietina is C+ red

I agree with your quibble in the sense that it would be useful to know exactly what is going on and to describe the phenomenon accurately. Although I have presented my provisional results above, they still need checking further. Either an anthraquinone in Xanthoria parietina reacts red with hypochlo...
by Mark Powell
Mon Dec 30, 2019 11:27 pm
Forum: Lichens
Topic: Xanthoria parietina is C+ red
Replies: 3
Views: 739

Xanthoria parietina is C+ red

I have long been an advocate of using strong bleaches such as Domestos and Parazone. Critics suggested that these were likely to be contaminated by sodium hydroxide and hence might give weak but confusing 'K' reactions in addition to C reactions. In order to reassure myself that such bleaches contai...
by Mark Powell
Tue Dec 17, 2019 7:58 pm
Forum: Lichens
Topic: ?Endococcus on Thelidium decipiens
Replies: 6
Views: 1233

Re: ?Endococcus on Thelidium decipiens

We should perhaps define the term 'interascal filament' in the glossary of the proposed LGBI3. An interascal filaments are any sterile hyphae that occur in between the asci. We are most familiar with paraphyses and periphyses but there are also pseudoparaphyses and others. For the ordinary observer,...