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RE: hybrids
While a complete explantation of taxonomy (the study of speciation, or how
to classify organisms into neat little categories that hopefuly will reflect
the reality of the complex relationships in nature) is rather beyond me, and
probably well outside the needs of this list, I think I can clarify some of
it. Please excuse the long post.
In the classical Mendelian view of species, if two different plants can
interbreed and produce viable offspring, then they are the same species. But
as in many areas of biology, this has proved far too simplistic a view. As
any orchid fancier will tell you, modern hybridizers in that field have
managed to cross not only different species in the same genus, but in some
cases three or four genera. New plants are given bizarre hyphenated names
like Brassio-Laelio-Cattleya to reflect that parentage. Some of these are
stunning, many more that never reach the market probably look like someone's
failed science experiment. And that is an industry that seems dominated by
'amateur' hobbyists.
To be sure, this is unusual, but plants in particular have a much more
complex genetic variability which allows for a lot more playing around by
those developing new strains (either as amateurs or professionals). Not only
hybrids are possible, but polyploidy as well, where instead of the usual
dual set of chromosomes you would expect, there can be 3 or 4 sets or more
(often referred to as diploid or polyploid). These plants are often more
robust, may or may not be viable, and often simply look like larger versions
of their parents. I don't know if anyone is deliberately doing this with
Echinodorus (as breeders of daylilies and irises have done) but this does
occasionally occur naturally, and some of the larger hybrids may have this
genetic trait.
A sport is usually a naturally occurring variation (not just the above
example, but also the occurrence of more or less spotting or marbling on
leaves, variegation, aureate or red(der) leaved forms, fused or lace leaf
forms, or even just a noticeably more robust form.) I suspect that in many
cases an amateur is equally able to spot these as a professional, the
difference being that a professional looking at a seed lot will have a
vastly higher number of plants to choose from. Once it is selected, it is
often referred to as a 'cultivar' (not to be confused with a 'variety' which
botanically speaking usually refers to a distinct wild population with a
specific trait not found in other populations. Unfortunately these two terms
are often used interchangeably in horticulture.)
But if Tropica is growing its plants from tissue culture (as was mentioned),
they are not going to get any of the wide variability of seed grown plants,
only the relatively minor genetic drift (random, ussally very localized
changes in the parents genetic material) associated with tissue culture.
Unless they are doing at least some seed propagation to vary their genetic
stock, they are unlikely to see much of anything in the way of new cultivars
themselves.
While I am also a bit concerned about hybrids or sports becoming weeds, the
fact is that most of the plants we grow in aquariums are not much of a
threat in most of the country, with the obvious exceptions of areas like
Florida and California where the winters are warm enough for the plants to
overwinter. Those that are hardy enough to survive are sadly mostly already
out there. I doubt if hybrids or sports pose a significantly greater threat
to native ecosystems than the straight species.
More to the point is how many people are willing to devote the kind of space
it will require to come up with something truly unique? Large nurseries that
work on the scale of millions of seedlings a year may come up with one or
two worth selecting every few years. This is possible in a field or maybe in
a large greenhouse, but how many of us have the tank space to provide room
for so many plants? The chances of a hobbyist poking along with more than a
few dozen plants or so in his basement are truly amazing. I'm with Dwight,
you can get much more satisfaction from going out and looking for new plants
already out there.
Orchid fanciers (and other hybridizers) often sell lots of unselected
seedlings to clear their greenhouse, taking a chance that the best ones are
the more robust ones that they can easily select out as seedlings. Nurseries
dealing in faster growing plants wait just long enough for them to flower.
This is how the mail order companies can afford to sell you "25 daylilies
for $5!" This is big business in the greater nursery industry, but I suspect
it is not such a big deal in a specialty market like aquarium plants. The
market is just not big enough for the large nurseries to bother with the
extra marketing involved.
I suspect that the odd Echinodorus Marble Queens are simply a partial
reversion closer to the 'normal' genetic traits of the regular species
(genetic drift again.) Sports often 'revert' to wild types if the genetic
trait that we find so admirable is not adaptive to the plant. Variegation is
particularly susceptible to this, since the white (or cream) parts are from
a lack of chlorophyl in that area. Without the extra photosynthes those
blank areas would normally provide, the plant may not be as well adapted and
start producing leaves with more green. As plantlets, the ones with the most
green are likely to grow faster than the others. All green ones will
probably be culled, but others that show less than normal may be included,
especially if the nursery needs to fill its quota of plants from a
relatively short supply. Variegation is the worst about this but as anyone
following the threads on red leaved forms can see other traits tend not to
be as fixed as we would like. Plants can adapt to their circumstances, and
some do so in ways we would rather they didn't.
As to hybrid Apons, didn't someone recently speculate that those 'betta
bulbs' sold in Petsmart and other big chains were a hybrid form? It also
seems to be possible that at least some of the difficulties in identifying
the various crypts may stem from hybridization, either in aqua-culture or in
the wild.
Brett Johnson
Green Man Gardens
bnbjohns @ home . com