Pennisetum setaceum 'Rubrum'

purple fountain grass


Pennisetum setaceum 'Rubrum'

(Forssk.) Chiov. 1923

pronounced: pen-ih-SEE-tum see-TAY-see-um

(Poaceae — the rass family)

common names: purple fountain grass, red fountain grass, red-leafed buffel grass

Pennisetum is from two Latin words, penna, a feather, and seta (sæta), a bristle or stiff hair on an animal, referring to the feathery bristles of the flowers of some species; setaceum is also derived from seta, which, I suppose, makes this ornamental grass doubly bristly!

This is a very showy and popular perennial grass from central Africa that grows in dense clumps of burgundy-coloured foliage, with arching purple-pink flower plumes in summer. It is decorative and durable as a landscape specimen or group planting, and also excellent in containers. It also offers good erosion control on embankments.

Apart from its colour, it is very similar to Pennisetum setaceum itself. Both grow to about 1.5 m high. The leaf blades are long and narrow, to 60 cm long and 3.5 mm wide, with small forward-directed teeth on the leaf margins and the upper surface. The flowerheads are up to 30 cm long. The cylindrical seed head has spikelets up to 6.5 mm long, and these are surrounded at the base by bristles mostly 1.5 – 2.5 mm long, with one to 4 cm long. The inner bristles are plumose.

Purple Fountain Grass is a sterile hybrid, but Fountain Grass itself can be highly invasive. It is much used as an ornamental in gardens and along roadsides, and is often found in motel gardens. Once escaped, it can form dense stands that exclude all other plants, and has become an invasive weed in the USA and in South Africa, where it has invaded hot dry sites, and greatly increases the fire risk. It has become naturalized in all the mainland Australian states and territories, less so in NSW than in the other states. The sterile ‘Rubrum’ is a much safer bet. Apart from its inability to spread very far, it is tolerant of high temperatures, humidity, wind, drought, and is even able to withstand light frost.

There is much confusion about the name of this grass, particularly in the USA. For many years some nurseries and references have listed it as a variety of Pennisetum setaceum, either ‘Rubrum’ or ‘Cupreum’, while others have listed it as Pennisetum macrostachys, confusing the issue further. All the native and introduced grasses of North America are now being examined taxonomically for their inclusion in the official Flora of North America, and early indications are that it will be called either Pennisetum advena or even Pennisetum x advena. It is actually thought to be a cross between Pennisetum setaceum and Pennisetum macrostachys (the latter also known as ‘Burgundy Giant’). In the probable new name, advena is Latin for ‘a newcomer or stranger’, so this would be rather a good name for it.


Photographs taken 2010, 2011, Picnic Bay
Page last updated 7th March 2019