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Pennisetum alopecuroides = Cenchrus purpurascens

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Cenchrus purpurascens

Swamp Foxtail

Pennisetum alopecuroides (L.) Spreng.
Cenchrus purpurascens Thunb.

Pennisetum alopecuroides, commonly known as Swamp Foxtail or Fountain Grass, belongs to the grass family Poaceae.

Pennisetum alopecuroides distributionAs the common name reveals, P. alopecuroides naturally occurs in moist conditions in flats below watercourses and in boggy areas. Its distribution ranges from tropical Queensland to the south of New South Wales mainly along the coast.

P. alopecuroides is a tufted or clump forming grass, that means, it does not spread by underground shoots. It has graciously arching leaves that grow to 80 cm long and bears feathery mostly purplish flowerheads on 60- 100 cm long erect stems. The inflorescence can be up to 14 cm in length and resembles a foxtail, hence its common name.

The slender arching leaves create a linear texture and scale that contrasts other growth forms and adds character to every garden or landscape.

P. alopecuroides changes its appearance and colour throughout the growing season showing an interesting aspect even when the peak flowering time of other plants has ceased. Usually the plant turns yellow in autumn after flowering. The grass has a luminous or translucent character, particularly when the sun stands low in the sky.

This ornamental grass is frost hardy to about – 7° C and grows in most soils even poorly drained soils. It is best grown in full sun or nearly so.

P. alopecuroides will propagate well from fresh seed and a most unified germination can be achieved if the seeds are soaked in water before sowing.

It will take one to two weeks for complete germination. The seedlings can then be pricked out into pots for further cultivation until they are ready for planting. It is important to keep the soil moist during cultivation of the seedlings.

Division of the root is another effective method for propagation. The root is cut up into sections containing several shoots and potted or possibly planted out in the garden bed. This method is to be used if identical reproductions of cultivars are wanted.

Both methods are preferably done in early spring, although the seeds can be sown all year if the temperatures for germination can be realised.

Warning  – P. alopecuroides is known to strongly self-seed. Therefore it is advisable to cut off the flowerheads before they shed their seeds and not to plant the grass near bushland. It has the potential to be invasive in some areas.

Advice from South Australia
Grass weed experts in South Australia have expressed concern about its introduction into that State because:

  • P. alopecuroides could be planted outside its range and become more widely naturalised.
  • P. setaceum (a weed from Africa) could be sold and distributed as P. alopecuroides as if it were native. This may already be occuring.
  • P. alopecuroides could prove not to be native to Australia.

The grass is a vigorous grower but responds well to fertilization. The Botanic Gardens use a standard slow release fertilizer low in phosphorus in the potting mix or liquid fertilizer during cultivation.

Once the grass is planted out it generally does not require fertilization as too many nutrients may suppress inflorescence production. The plants are maintained by cutting back the old foliage in early spring by about two thirds of its length.

Flowering time is in summer from January to June. The inflorescences are valuable in flower arrangements.

P. alopecuroides can be used in many garden situations such as rockeries, bogs, near ponds and as groundcover.

Text by Petra Wilhelm (Botanical Intern 2003)

References

Flora of Australia Volume 44, Poaceae 2 (2002). Melbourne ABRS/CSIRO Australia

Romanowski, N. (1993) Grasses and Bamboos and Related Plants in Australia.

Sharp, D. & Simon, K. S. (2002) AusGrass: Grasses of Australia. ABRS Identification Series.

Wrigley, J. & Fagg (1996) Australian Native Plants. Propagation, cultivation and use in landscaping.

Darke, R. (1999) The colour encyclopedia of Ornamental Grasses

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