north american native orchid journal - at The Culture Sheet

Folsom: A CASE FOR EVOLUTION
Casual observation can often notice
differences in related species. Spiranthes
cernua—a compilospecies—show gene
flow or influence, from the basic diploid
species that are found within its range. In
the Northeast, Spiranthes cernua shows a
marked influence of S. ochroleuca and in the
Midwest of S. magnicamporum. Spiranthes
diluvialis, an allotetraploid species derived
from S. magnicamporum and S. romanzoffiana
has evolved into a solid, wide-ranging
species that although still rare, often
occurs now where neither ancestral parent
may be found (Sheviak, 1984).
Lastly, alien species have arrived
whether having been borne in on storm
winds or hitchhiking a ride in cargo from
far off lands or brought to our shores as a
garden plant. An example in Florida is
Zeuxine, the lawn orchid, our only annual
orchid, and has seeded in all over the place
but does not drive out native species.
Zeuxine has been documented to have
arrived in lawn seed from the Far East in
the 1920s. Another example would be
Oeceoclades maculata, the African spotted
orchid with its beautiful mottled leaves.
This species started to appear about 25
years ago and has now insinuated itself
through central and southern Florida. It is
S. diluvialis
assumed it first arrived as wind-borne seed from Africa and has
also colonized several islands in the Caribbean. Further north
Epipactis helleborine, the broad-leaved helleborine, has been known
in North America for more than a century after it was first seen
near Syracuse, New York. It is now found throughout most of
temperate North America and shows a decided fondness for
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