The common name of a small tree (Brugmansia candida) that was originally part of the Datura genus (The most well known of which is Jimsonweed). The name was later changed when part of the Datura genus was split off to form Brugmansia. Both Datura and Brugmansia are part of the family Solanaceae, which includes tomatoes and a whole bunch of other useful stuff.
They get to be about three meters high here (in Hong Kong) and are brittle, so they don't grow well in windswept areas. Other than that, they're perfect for this climate: hot and humid. They do produce the anticholinergic atropine which can be an extremely unpleasant drug to take.
They are grown, however for their beautiful flowers which are long, white, cones that hang down. The base of the cone tapers out into five points. Very picturesque.
Incidentally, I have observed that extremely bizarre insects tend to live on them. I would hazard to guess that this is because of the chemistry.