>Nepenthes is a vine. What is its twining habit? Does the stem itself
>entwine
Yes and no, e.g. some forms of _N.veitchii_ are known to clasp the stems of
trees with their leaf blades (let us call the photosynthetically active
part of the _Nepenthes_ leaf a blade or lamina, in order to make things not
even more complicated...).
>, or does it rely largely on the "tendril action" of the "tendril"
This is largely and mostly the case in _Nepenthes_.
>portion on the leaf, between leaf blade and pitcher. (is this properly
>called a tendril?).
Let us call it the tendril.
> Do the leaves on the upper growth generally stay two-ranked (distichous)?
No, not generally. It depends on the species, light, growth conditions, etc.
Kind regards
Jan