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Re: hybrids and correction


Narda:

>One of the ladies said something about so and so being a species and 
>a friend  said "well you know there are no true species in the genus 
>hosta,"

Statements like this are usually intented to be a pun, with just a bit 
of truth thrown in.

In the animal world, species are fairly well defined and the different 
species don't hybridize readily.  In the plant world botantist have 
been trying to define what a species is since the time of Linnaeus and 
have yet to come to a definitive answer.  There are two camps of plant 
taxonomist - the splitters and the lumpers.  The splitters will 
seperate plants into new species on the simplest of differences while 
the lumpers will throw in a large amount of variability into one 
species.

The difference between the animal species and plant species is that 
animals are better adapted at recognizing members of their own species 
because they have sight and various hormones to attract their own 
kind.  Animals also move about, so you don't get the local build of 
variation that can occure in plants.  In plants pollen only traves so 
far and the resulting seeds usually only travel a limited distance.  
Thus, any variation that develops in a plant can only spread slowly.  
Take, for example, a sugar maple tree in Vermont that develops deep 
purple leaves.  That maple tree will only spread its pollen so far and 
the resulting seeds will only fall a few hundred feet away.  A 
resulting seedling may grow a few hundred feet away that is also 
purple, but it will take some time before it matures and is able to 
shead pollen and produce seeds that will further spread the purple 
leaf color.  Now, over a period of centuries all the maples in that 
area may become purple leafed.  A botantist may then come in and see 
all these purple leafed maples and call them Acer saccharum var 
purpurium, but a spliter type may call them a new species, Acer 
purpurium.  

Also, plant species tend to cross among themselves where the species 
overlap resulting in hybrid populations.  These hybrid populations can 
then backcross to the species and the backcross plants can further 
backcross to the species.  By repeately backcrossing a hybrid between 
two species it is possible to bring in traits from one species into 
the other species.  This is call introgression.  It is also confusing 
to the taxonomist because these individuals will have all the main 
traits of one of the species, but also a few traits of the second 
species.  Is this a new species?  

Thus, some people take the extream position and say that there are no 
species, that every plant is an individual.  This is usually said with 
a big grain of salt, but in a way it has some validity behind it.

I have more experience with the daylily species then I do hosta 
species.  Relatively few daylily species were brought over to the US 
and Europe, and I suspect this is somewhat the same with hostas.  It 
is also true with the true lilies.  The daylily species in the US can 
be more or less defined into about a dozen species.  We know what 
these species look like.  However, we are now starting to get some 
daylilies from China and Korea and we have no idea of where they fit 
in.  Part of this problem is that we don't know much about the natural 
distribution of daylilies in Asia, in particular, China.  This is also 
probably true with hostas.  Also, with hostas a lot of the species 
that are in the US and Europe came from gardens in Japan and who knows 
where the original plant came from.  They may have been seedlings that 
were grown in the garden, but their history was lost.  They may not 
even exist in the wild.

There are all sorts of research tools available today that can help 
the plant taxonomist sort all of this out, but these techniques are 
EXPENSIVE to use.  

Joe Halinar

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