Collection location: El Dorado, California, USA [Click for map]
This specimen is clearly of the same type—perhaps an Amanita species—as my observation 83241. It was growing in soil in a grassy area adjacent to a clump of live oaks. Maximal diameter of cap was 16.5 cm; length of stipe was 16 cm. Cap surface is slightly sticky, probably from recent rain, resulting in some adhering dirt. Wart-like structures on cap surface—presumably universal veil remnants—were white and almost entirely restricted to center of cap. Cap cuticle is tan, with a sort of metallic sheen. There is a thin superficial layer of torn tissue mid-stipe in this specimen, and a couple layers of torn tissue like a volva at the base. Stipe has slight flair to widen just below cap, otherwise straight until widening at base, then tapering to a point. Spore print white.
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The shade of a building, a tree, forest canopy, even a handy-dandy clipboard or field guide or accommodating acquaintance can block the sun. When I was in China, Dr. Yang used one of my reflectors as a sunscreen.
Thanks once again for taking the time for the explanation, I’m convinced! There are apparently more than enough unknowns in the mushroom field that we need to control the things that we can control and collect the best quality samples/observations possible as the foundation…garbage in, garbage out as they say. I’ll dry this sample per your suggestions.
Re: pictures, brilliant sunshine is the rule around here, so I will need to wait for the less common cloudy day to try again on pictures…I see one other sample of the same type growing.
First, you’re more than welcome.
If material in good condition is dried quickly, the cell structure can often be restored by warming a thin section of tissue in a dilute base such as 2-3% KOH or ammonia solution of slightly greater strength. Since in working up a full microscopic anatomy of a species one rarely has fresh material to work with, microscopic studies have developed around dried material. It can throw a monkey wrench into the process when material is not dried well or has not been preserved well (attacked by molds, insects, etc.), but using dried material is the way the science is done in dealing with macroscopic biological organism and the way mycology has gotten done since microscopes became a critical tool in the study of mushrooms. It may seem odd, but the modern methodology of studying Amanita (for example) did not really begin in earnest before the thesis of Dr. Cornelis Bas (published in 1969). The methodology has been revised and extended a little bit since that time by Dr. Zhu-liang Yang and myself. Many papers about Amanita have been published in the last 42 years treating Bas’ thesis as if it were only a key to sect. Lepidella instead of the record of a methodological break through. And, of course, there aren’t very many mycological taxonomists working on any given genus. And, of course, sometimes we make “negative progress.”
And well-dried herbarium material that has been well-identified by a specialist is a very reliable source for molecular studies.
The bottom line regarding drying is that we can’t really do morphological mycology without dried specimens, good photographs, good notes taken on fresh material, good methodology, good scopes, trained people, etc. The hardest thing to find is a trained person with the time to work on a particular issue. Rare, rare, rare.
We can check the stipe tissue and a gill cross-section to see if the specimen really is an Amanita. (Mistakes of that sort do get made.) In the case of the present species, a mature, dried specimen has spores that will (in Melzer’s Reagent) tell whether the present species is in subgenus Amanita (inamyloid spores) or in subgenus Lepidella (amyloid spores). If your material is pantherinoid, then it should have inamyloid spores. We can stain a thin slice of gill and see if there are clamps on the bases of basidia. They shouldn’t be there if the species is pantherinoid. We can measure spores to see if they fit into the size-shape concept for one or more pantherinoid taxa. Then to get to a specific ID it may get fairly hairy especially when we don’t have detailed anatomical knowledge for many “known” species…as can be the case in many places in the U.S.
I really appreciate the photographic advice; I know I’m doing an injustice to these nice specimens with my amateur photography. I have a basic camera but wasn’t using its macro setting capabilities, which together with your detailed suggestions on lighting should help a lot.
Can you explain the value of drying the specimens for ID?
I’d cut the cap into at least 8 pie slices to encourage quicker drying. Likewise the stem should be cut lengthwise at least in quarters for drying.
If you’re camera allows the aperture to be set to a high-numbered f-stop (like at least 16 and preferably 32), I’d suggesting setting the f-stop as high as you can to get the maximum depth of field and letting the camera pick the shutter speed. A tripod or a beanbag will be needed because the exposure will probably be longish. Then I’d suggesting shooting in shade with open sky above you. Don’t use flash. Make little “book covers” out of two sheets of cardboard from tablets of writing paper and cover these with aluminum foil to make a set of three reflectors that you can use to diminish or eliminate any shadow. You’ll need something to lean these reflectors onto so that they reflect the sky’s light into your set up. I think this will suppress the glare, deepen your depth of field (with practice you can get everything into focus), and suppress shadows. This will reduce a lot of the problems with large pale-colored objects. A gray (rather than blue) background will avoid some of the color distortion that is caused by colored backgrounds…in such situations, the eye/mind does/do a lot of stuff that you’d prefer it/they not do when you’re trying to get an accurate mental image of color.
I’d have to agree that the description of the Amanita pantherina group matches this observation well…thanks.
Created: 2011-11-27 10:05:19 CET (+0100)
Last modified: 2011-11-29 05:20:16 CET (+0100)
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