Yes, but their stem nature isn't always very clear. Thus, I'd
prefer to call them phylloid organs (this is a descriptive term not
too much fixed morphologically).
>I am
>also under the impression that the traps of Utricularia are derived from
>"true leaves" (modified leaves, not modified stems like the photosynthetic
>organs on Utricularia).
I think that impression is correct.
>If so, are the traps the ONLY structures on
>Utricularia with a foliar origin? What about the bracts on the scape?
The bracts as well as all parts of the flower are quite "normal",
i.e. of foliar origin. Indeed, the flowers are the only organs of
_Utricularia_ which undoubtedly show it to be closely related to
_Genlisea_ and _Pinguicula_, and Lentibulariaceae is probably
the most natural of all cp families with several genera!
>The floats on some Utricularia (ie. U. inflata) are derived from stem
>tissue, not bladders, I would assume?
The floats are definitely not derived from the bladders. The bladders do indeed represent an end point of differentiation
(like flowers). As far as I know, no other organs (stems, phylloid
organs, inflorescences) are ever formed from bladders or
flowers.
>Does Genlisea have the same idiosyncratic anatomy as Utricularia? ie. are
>Genlisea traps modified leaves, are Genlisea leaves actually modified stems?
No, _Genlisea_ has true stems and (quite) true leaves. But
morphological plasticity is greater than in _Pinguicula_.
>Does this plant also totally lack true roots?
Yes. Roots are replaced here by the trap leaves (evidently
derived from true leaves). Here too, only the flowers prove this
genus to belong to Lentibulariaceae.
Kind regards
Jan