US Botanic Garden

Two flowers of Aristolochia littoralis, a native of Brazil.

The red inflorescence of a hohenbergia (bromeliad family).

This is a Brazilian member of the melastome family, probably a tibouchina (same genus as the "princess flower" grown a lot in California).  This one was close to the entrance of the greenhouse.

Melastomes usually have distinctive leaves, with a few parallel veins running from the petiole to the leaf tip, connected by net veins at right angles to them.