> Which leads me to ask - does a whole genus or family have to be
> deemed carnivorous because it contains carnivorous species? Or
> to put it another way - is it necessary that all species in a genus
> (or genera in a family,) should be demonstrably carnivorous in
> order to classify a/some species as such?
The answer is: NO.
Example: Dioncophyllaceae, only one species of 3 known (_Triphyophyllum
peltatum_) is (part-time) carnivorous, whereas not even the slightest trace
of carnivory (OK, the flowers might *attract* pollinators...) could be
found in the other two.
But whereas in Dioncophyllaceae, the one cp is "complete", in Bromeliaceae
all transitions from non-carnivorous to nearly carnivorous (but never
"completely" carnivorous) can be observed. The "problematic" Sarraceniaceae
do have some "complete" members so it can at least be supposed with some
reason that some cp criteria have been lost by reduction (which is not at
all likely in the bromeliads).
> Oh, and "two of three"? Did I dream it, or didn't someone find
> enzymes in Darlingtonia recently? That would surely make three
> (and tidy up the aesthetically messy situation at a generic level.)
I would be appreciative for any literature reference here (for more than
purely aesthetical reasons).
> If the plants have gone to the trouble of evolving enzymes, I
> should think they must also have developed the means to make use
> of the resultant nutrients. Else what advantage to sustain the
> characteristic in the face of ongoing evolution?
Who knows (maybe Barry)? As I have mentioned already, I do know too little
of the actual evidence to be able to make any useful statement.
> Maybe these are the most unusual plants then! Perhaps there
> should be an _International Non-Carnivorous Plant Society_ devoted
> to the study of wind-pollinated grasses and pondweed :)
Yes, maybe. Would you like to go as a candidate for president of INCPS? 8-)
> (I'd guess most algae fits the bill as non-cp also.)
At least several "algae" (e.g. _Euglena_) are somewhere in the zone between
plants and animals (like fungi), so here we would get these nasty
carnivorous-?PLANT discussions, again.
> Perhaps there's a holocarnivore out there waiting to be found -
> (now that I'd like to see!) Though I dread to think of the
> environmental conditions necessary to promote such a thing unless
> it could arise from albino mutations or somesuch.
Well, and I am one of these old-fashioned/dull guys who think that the
organisms which have really been discovered (and their study) are already
strange and interesting enough...
Kind regards
Jan