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Species? Varieties? Cultivars?

Steve wrote:

>When we start to examine the differences between species and varieties
>with the aid of chromosome and DNA analysis, I think we are finding that
>there is a whole lot of grey area and that there really is no clear
>delineation between speciation and varieties. If you were to examine
>canines, you'd find enough variation to suspect there are hundreds of
>species of dog yet these dogs are a single species because they can all
>be bred together successfully. I think that is the definition of a
>species but you biologists will probably correct me.

That's one of the things that is looked at, but there are _many_ species of
animals and plants that can interbreed.  Sometimes the offspring are
fertile, other times the offspring are mules.  I think what we're finding
is that the definition of the word "species" is becoming a very slippery
thing.  It's more an expedient to be able to put a handle on something than
anything else.  

>We aquarists prefer to believe that there are lots of species (or
>varieties) because we are always searching for something new and unique
>and perhaps *rare*! Good news, if aquatic plant breeding becomes as
>popular as creating new cultivars of roses and begonias, we will have no
>shortage of new Sword plants, Ferns and Crypts in the years to come.

That time is now!  Look at all the cultivars we already have at our
disposal, and believe me, there are many more in the wings that have just
to wait until there are enough individuals in propagation to make it
worthwhile to distribute them commercially.  There are more being developed
Karen Randall
Aquatic Gardeners Association