The members of this robust genus are known collectively as Fountaingrasses, and range from petite to enormous, from frost tender to hardy, and from annual to perennial.
Elephant Grass (Pennisetum purpureum) can reach a height of 7 metres (23ft.) in its native Africa, whereas Pennisetum alopecuroides only grows to 0.6 meters (2 ft.)
As some species of Fountaingrass will not survive cold winters, check which species you have, and if necessary grow it in a container that can be kept indoors during winter.
Many Pennisetum occur in the natural habitats of the Sulcata and Leopard tortoises and all are considered safe to feed, but they do have a reputation for accumulating oxalates
and soaking up nitrates from the soil, so try to grow on a low-nitrogen compost.
Do not confuse with Miscanthus, which is also called Elephant Grass but is a different plant, or with other types of Millet, which belong to the same family but a different genus.