Appearance
Most giant puffballs grow to be 10 to 50 centimetres , sometimes to be 90 centimetres in diameter; although occasionally some can reach diameters up to 150 centimetres and weights of 20 kilograms . The inside of mature Giant puffballs is greenish brown, whereas the interior of immature puffballs is white. The large white mushrooms are edible when young.The fruiting body of a puffball mushroom will develop within the period of a few weeks and soon begin to decompose and rot, at which point it is dangerous to eat. Unlike most mushrooms, all the spores of the giant puffball are created inside the fruiting body; large specimens can easily contain several trillion spores. Spores are yellowish, smooth, and 3 to 5 micrometres in size.
The classification of this species has been revised in recent years, as the formerly recognized class Gasteromycetes, which included all puffballs, has been found to be polyphyletic. Some authors place the giant puffball and other members of genus ''Calvatia'' in order Agaricales. Also, the species has in the past been placed in two other genera, ''Lycoperdon'' and ''Langermannia''. However, the current view is that the Giant Puffball is ''Calvatia''.

Status
"Widespread and fairly common, and not considered of conservation concern in the UK. However, it is protected in parts of Poland and considered rare in Lithuania and of conservation concern in Norway."Uses
Puffballs are a known styptic and has long been used as wound dressing, either in powdered form or as slices 3 cm thick. The fungus was often harvested prior to battles for this purpose.It is the main source of the anti-tumor mucoprotein calvacin, which is present only in tiny quantities.
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