upheavals (Hurricanes, etc)?  Seems like an asteroid would cause a wealth of 
upheaval...  But then again isn't this a relatively old species?  Aldrovanda
is known from fossil records and is very similar.
What if the southeast remained a haven for Venus Flytrap for a few million 
years into the future (instead of turning into trailer parks and beach 
resorts)?  What forms might have evolved?  Giant traps?  Vines?