rarity

[Anita Cholewa]

Regarding rarity of plants, Tom made a good point -- it is
relative.  Unfortunately, since the government and natural
heritage programs maintain lists of "rare plants" it does
become important to define it otherwise.  As botanists I think
most of us do consider rarity in terms of abundance or in terms
of extremely limited habitat (in the sense of the habitat being
found in only a few locations).  The rare plant programs on the
other hand frequently include plants as rare because the habitat
is or has become fragmented even though the number of plants may
be high (e.g., Cypripedium candidum is on our state "concern" list
because the original habitat is now limited but the numbers of
individuals of the orchid is quite hight) or even though the
number of habitat fragments may be high (but widely scattered).
I guess it really is relative, as Tom said, to why rarity is being
considered in the first place.  A statistician once told me that
there really were no rare organisms; we just weren't sampling correctly!

Anita

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