SIX MISUNDERSTOOD SPECIES OF AMANITA* 
By GEORGE Е. ATKINSON 
Cornell University 
Recent monographs of the Amanitas have not lessened the 
obstacles in the way of recognizing the species of this difficult 
genus. On the contrary, they have introduced certain elements 
of confusion. This is evidenced by a compression of the number 
of species in regions where there has not been an opportunity of 
studying living plants but only dried material has been examined. 
In quite restricted localities where intensive studies have been 
made there has occurred a lively splitting process resulting in 
the multiplication of species based to some extent on trivial char- 
acters, the result of environmental and growth influence. I wish 
here to call attention to several of the species which have been 
misunderstood. 
Among the pure white Amanitas in the eastern United States 
there is one species which is easily recognized from all the others 
usually on sight, but with certainty after a microscopic examina- 
tion. This is Amanita bisporigera.t It is a species with a white 
volva with apical dehiscence and a prominent limb. The pileus 
is smooth, viscid, and glistening white. The stem is pure white 
and slender. The basidia are constantly two-spored. The spores 
are globose or subglobose. 
Its nearest ally is a similar white species with four globose 
spores to а basidium. This four-spored species is a robust plant, 
interpreted in this country by some as Amanita verna, by others as 
a white form of А. phalloides.t Amanita bisporigera is dis- 
* Illustrated by lantern slides. 
T Amanita bisporigera Atkinson. Bot. Gaz. 4 
i Amanita Шашы, is placed іп Amanita ius by Murrill (Mycologia 4: 
240. 1912; and N. Am. Fl. то: 70. 1914), although тя, enia from the 
typical Amanita phalloides of Europe. Coker (Coker, W. C., The Amanitas of the 
Eastern United States. Jour. Elisha Mitchell Sci. Soc. 33: LE pl. 1-69. 1917) 
places Amaniia bisporigera as a synonym of Amanita "verna." This four-spored 
white Amanita of North America was also interpreted by me as Amanita verna (see 
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