This remarkable cactus goes by the common name of Queen of the
night or Orchid cactus. They have large flowers, roughly 10 to
15 centimetres across that bloom only after sundown and wilt by
dawn.  The cactus belongs to the genus Epiphyllum, a name
meaning "upon the leaf" because the flowers are sent out from
the edge of the plant's "leaves" (They are actually stems). The
most common species are Epiphyllum hookeri, Epiphyllum strictum
and Epiphyllum stenopetalum. The first name was given by Adrian
H Haworth in homage to Sir William Hooker, the first botanist to
record the plant, albeit incorrectly, as Cactus phyllanthus.
Native to areas south of Mexico, including Guatemala, Costa
Rica, Guyana and Venezuela, the cactus has found renown around
the world as an ornamental plant. Thus the original white and
yellow petalled flowers now have many colourful variants due to
hybridization with related genera, such as Selenicereus,
Hylocereus, Heliocereus and Nopalxochia.  Apart from the obvious
ornamental and nocturnal