S.purpurea subsp. purpurea: has long petioles and the pitchers
tend to be longer, though not wider. Infact the opening on them
can actually be slightly constricted.
S.purpurea subsp. venosa: short and fat. It often appears that
there is no petiole and the pitcher is like a funnel going right
into the rhizome. There is of course, it's just very short. Also,
the pitchers tend to be shorter and can be very wide mouthed.
I think venosa plants from New Jersey to North Carolina are the
best looking and easiliest grown. There are venosa plants from
Florida which have lilac/pink petals and go by the name S.
purpurea subsp. venosa var. burkeii (sp?), though I prefer the
Northern S.purpurea purpurea plants to them in terms of the color
of the leaves.
Dave Evans
P.S. the most commonly cultivated are those from between NJ and
NC (SC?).