section 9: presence of a volva at stem base
The volva is constituted by the remains of the enveloppe (the "veil") which contained the initial visible part of the mushroom (the spore-carrying part), before its growth. For most fungi, this veil disappears very quickly when the "mushroom" grows, leaving only small traces, if any. For others, a part of it may remain under the form of a volva at the stem base. This volva may be sturdy, in which case it remains as a sheathing "sac" at the base of the stem, or on the contrary very fragile, in which cases it disrupts itself into small pieces soon disappearing.
The volva may take several forms:
- "sac" - it is then quite visible and looks like a little bag sheathing the base of the stem ;
- "circumcised" - it is also visible, and looks like a ridge making a trough or gutter around the stem base (as if the sheath had been neatly cut off);
- "brittle" - it only remains as warts or reams usually quickly disappearing;
In all cases, one must dig around the stem base of mushrooms (especially those suspected to belong to the Amanita or Volvariella groups), to highlight the potential presence of a volva. In order to simplify, a hardly visible brittle volva or the absence of a volva are treated very similarly by the engine. In a same frame of mind, we don't make any difference between the various types of volva. When in doubt choose "I don't know" to avoid taking into account this criterion. The presence of a volva being a very important distinctive feature, we can also impose this feature by checking the "force selected answer to criterion" box. This will exclude all mushrooms which do not conform to the feature from the search results output (eg in this case, exclude all mushrooms which do not have a volva).
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|The volva is here obvious and sheathing (mushroom on a tree). The answer is "yes"||   ||The volva is here circumcised, the "gutter" is clearly visible. The answer is "yes"||   ||We can see here volva remains, which will soon disappear. The answer would be "yes", but we could do with a "no" all the same||   ||We don't see here a sac, or a ridge, there is no volva: The answer is "no"||   |
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|The volva is here obvious and sheathing, (even though the stem base is not bulbous). The answer is "yes"||   ||The volva is here obvious and sheathing. The answer is "yes"||   ||We can see here the ridge and the warts, indicating a volva. The answer is "yes"||   ||We can see here the ridge making a gutter, indicating a circumcised volva. The answer is "yes"|
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