Cardon = Pachycereus pringelei, looks like a saguaro, gets bigger.
Senita = Lophocereus shottii, long spines on top, short ones near the
bottom. The monstrose form of this is called the "totem pole cactus".
I am led to believe that the leaf, tendril and pitcher of Nepenthes is
all a modified leaf blade. Imagine a normal leaf folding up to make
a Sarracenia. Now imagine the Sarracenia leaf base unfolding out again
to form a flat leaf with the picher at the end. The anatomy of Sarr
pitchers is different from that of Nepenthes, but it looks like
this sort of thing may have happened. I havn't seen anything written
on it (probably some German did in some old 1920's journal) but watch
some Nepenthes seedlings and see. Ontogeny recapitulates phylogeny?
MJC