This member of the Cactaceae
family was given
this name by Nathaniel
Lord Britton and
Joseph Nelson Rose in 1909. It is found in
Mexico and Texas, growing in grit with little water and some to lots
of sun. The caudex will grow up to 30 centimetres or more, the
branches will reach for up to two meters. The large white
flowers will appear at night.
The genera name from pene;
'thread' and Cereus another member of the Cactaceae family, as to
plant form. The species name after Josiah Gregg, 1806-1850, an
US-American cactus collector.