The GWM strain originated as a cross between the Porto Rican strain, and the regular 'A' strain.
There are several isolations (iso) or variations of this particular mushroom in the wild, and all are said to produce subtle differences in appearance and growth patters.
The Iso B produces primarily leuistic spores. which means that any mushroom that may grow from those spores will likely be lacking in pigment similar to an albino. It differs from albino spores however, in that these spores retain their normal color and will drop in abundance.
In the wild the 'GWM iso B' colonizes fast and fiercely. It fruits prolifically and can produce monster sized mushrooms (hence the name). The caps are usually a silver/white/buff, with white stems and some blueing where bruised.
We at Spores101 consider this variety of cubensis one of the most beautiful and well rounded strain of its species. A rewarding find in the wild, and a beautiful study under the microscope!
*For microscopy research only and not available in the US states: California, Georgia or Idaho.