African Feather Grass

Pennisetum macrourum Trin.

Family: Poaceae.

Names:

Pennisetum is from the Latin penna meaning feather and seta meaning bristle and refers to the feather like bristles on the flowers, of some species in this genus.
Macrourum is from the Greek makros meaning long and ura meaning tail and refers to the long tail like seed head.
African Feather grass refers to its origin, the feathery bristles on the seed and its grass like leaves.

Other names:

Beddingras (South Africa)

Summary:

African Feather Grass is a robust, rhizomatous, perennial grass eventually forming dense overhanging tussocks up to 2000 mm in height. In many ways these tussocks resemble those of Pampas Grass.

Description:

Cotyledons:

One.

Leaves:

Mostly basal, hard and bristle like.
Blade - Parallel sided, 400-1200 mm long x 4-12 mm wide, sometimes drooping, up to 5 leaves per stem. On emergence the leaf is rolled inwards, but later the lower part of the blade may flatten, leaving only the tip rolled. The upper surface of the blade is a whitish green with prominent ribbing. The lower surface is smooth, a darker green, purple along the edge and at the tip. The ribs on the upper surface and the edges of the leaf bear minute upward-pointing teeth, so that the leaf feels rough if the fingers are run down it. The tip is finely pointed or has a bristle like flexible point. The leaves are tough and harsh and are unpalatable to stock.
Ligule - Fringe of hairs, 0.5-1.5 mm long.
Auricles -
Sheath - Rounded on the back, papery but firm, striped.

Stems:

Densely tufted, erect, cylindrical, unbranched, hairless. Creeping, often stout and strong rhizome.
Flower stem - Erect, up to 2000 mm tall, stout towards the base, hairless but roughened below the panicle.

Flower head:

A narrow, erect, dense cylindrical spike like panicle, 80-300 mm long x 8-20 mm diameter, at the ends of the stems, pale green to straw-yellow to brown or purplish, with prominent bristles 10 mm long protruding from the body of the spike. When ripe the spikelets containing the seed fall away, leaving the bare, roughened stem.

Flowers:

Spikelets - Many, 4-7 mm long, narrowly egg shaped, pale, stalkless, acute tip, smooth and hairless, single or paired near the base of the panicle. Many, roughened bristles underneath that are just shorter to slightly longer than the spikelet and one which is awn like, stouter, 8-15 mm long and appressed to the axis or erectly spreading.
Florets - Lower one empty and reduced to a lemma. Upper one bisexual.
Glumes - Lower one tiny or absent, otherwise similar to upper glume. Upper glume 1-3 mm long, egg shaped or rounded, translucent, 1 or no nerves, pointed tip.
Palea - None on the lower lemma. Narrowly egg shaped on upper floret.
Lemma - Lower one as long as the spikelet, membranous, firm, translucent, 5 nerved, pointed tip, short awn. Nerves sometime purple. Upper lemma similar.
Stamens -
Anthers -

Fruit:

Yellow brown, 5-7 mm long. Hairy.

Seeds:

Enclosed in the fruit.

Roots:

Fibrous roots to 1000 mm deep. Rhizomes, 2000 mm long x 5-7 mm diameter, partly enclosed in sheathing scales, from the surface to 300 mm deep in the soil, roots and shoots form at the nodes.

Key Characters:

Tufted. Inflorescence a narrow panicle, 100-300 mm long, sometimes purplish with bristles rarely exceeding 15 mm long.

Biology:

Life cycle:

Seed germinates in autumn but rarely establishes. About 7 months after germination, young plants that have survived will start to form rhizomes. These elongate and produce new shoots and roots from the rhizome nodes in spring and early summer. Within 3 years a dense clump about 1500 mm round has been produced. The rhizomes grow mainly in spring and summer. Established plants flower from spring to summer and seed is normally ripe by late summer. Over winter the plants are semi dormant. Rhizome fragments moved by cultivation or mechanical control readily transplant.

Physiology:

Established plants are drought resistant.

Reproduction:

Seed and rhizomes.

Flowering times:

October to April in SA.
October to February in Perth.
Spring to summer in WA.

Seed Biology and Germination:

Up to 88% of seed is viable but seedlings are rarely seen in the field.
Over 100,000 seeds per square metre have been recorded.
Maximum germination occurs when seeds are shallowly buried. No establishment occurs from depths greater than 80 mm.
Most seed has little dormancy but a few remain viable for several years.

Vegetative Propagules:

Creeping rhizomes.

Hybrids:

Allelopathy:

Population Dynamics and Dispersal:

Most spread has resulted from intentional planting for ornamental purposes and disposal of garden refuse containing rhizomes and dried flowers.
Established infestations can extend rapidly by rhizome production. If the rhizome is broken and moved by cultivation the growth from these buds will start a new colony. An invaded area generally carries an irregular cover of large tussocks with smaller ones arising as offshoots from the parent plants. Eventually as the plants steadily spread by this process the invading species can completely dominate the original vegetation. Established African Feather Grass plants have the potential to produce large numbers of seeds although seed production varies from year to year. The barbed bristles on the seed husk assist its spread by wind or in the hair or wool of animals. Some spread along roadsides has probably resulted from dispersal of the feathery spikelets by the wind of passing vehicles. Seed is also spread in water and streams.
It rarely establishes or persists in shaded situations.

Origin and History:

South Africa.
Probably introduced to Australia in hay for horses returning from the South African War.
First recorded in Victoria in 1904.

Distribution:

NSW, SA, TAS, VIC, WA.
In Tasmania known infestations are restricted to areas in the Huon and Derwent valleys and has been almost eradicated.
In other states it occurs in fairly discrete and isolated infestations.

Courtesy Australia's Virtual Herbarium.

Habitats:

Mostly confined to road sides and the banks of rivers and creeks, with occasional incursions into pastures. Infestations may also occur on dry and sandy banks and established plants are drought-resistant.
Open sunny areas.

Climate:

Sub humid warm temperate with an annual rainfall greater than 600 mm.

Soil:

Plant Associations:

Significance:

Beneficial:

Ornamental.

Detrimental:

Coarse and unpalatable to stock. Young growth after cutting or burning is sparingly consumed.
Dense stands completely dominate any pasture species, making the infested area useless for grazing reducing access to streams and water.
It harbours rabbits and is a fire hazard.
Weed of wetlands, roadsides, rivers and streams, pastures and disturbed areas.

Toxicity:

May cause nitrate toxicity.

Legislation:

Noxious weed of NSW, SA, TAS, VIC and WA.

Management and Control:

Chemical control is expensive.
Other control measures have generally proved ineffective.
Cultivation must be thorough and regularly repeated for control otherwise infestations will become worse. Rhizome fragments can establish new plants when buried 150 mm deep.
Glyphosate and flupropanate have provided good control.

Thresholds:

Eradication strategies:

Spray plants until just wet with a mixture of 1000 mL of glyphosate 450g/L plus 250 mL of Pulse® Penetrant in 100 litres of water in late spring and autumn each year. Burn or slash tops 8 weeks before or after spraying.
Isolated plants amongst other vegetation can be treated by selectively wiping leaves and stems with a mixture of 1 part glyphosate in 2 parts water.
Fluazifop can be used in sensitive situations where a high degree of selectivity is required.
Plant trees to provide shade over the infested area.

Herbicide resistance:

Biological Control:

Related plants:

Elephant grass (Pennisetum purpureum)
Feathertop. (Pennisetum villosum)
Fountain grass (Pennisetum setaceum)
Kikuyu (Pennisetum clandestinum)
Mission grass (Pennisetum polystachion)
Pearl Millet (Pennisetum glaucum)
Swamp Foxtail (Pennisetum alopecuroides) has a longer seed head, smaller spikelets and smaller bristles.
Pennisetum pedicellatum

Plants of similar appearance:

Pampas Grass (Cortaderia selloana) is similar to African Feather Grass but the shape of the flower head readily distinguishes them.

References:

Auld, B.A. and Medd R.W. (1992). Weeds. An illustrated botanical guide to the weeds of Australia. (Inkata Press, Melbourne). P52.

Black, J.M. (1978). Flora of South Australia. (Government Printer, Adelaide, South Australia). P229.

Hussey, B.M.J., Keighery, G.J., Cousens, R.D., Dodd, J. and Lloyd, S.G. (1997). Western Weeds. A guide to the weeds of Western Australia. (Plant Protection Society of Western Australia, Perth, Western Australia). P62-63. Photo.

Hyde-Wyatt, B.H. and Morris, D.I. (1980) The Noxious and Secondary Weeds of Tasmania. (Tasmanian Department of Agriculture, Hobart, Tasmania). P18-19. Diagrams.

Lamp, C. and Collet, F. (1990). A Field Guide to Weeds in Australia. (Inkata Press, Melbourne).

Marchant, N.G., Wheeler, J.R., Rye, B.L., Bennett, E.M., Lander, N.S. and Macfarlane, T.D. (1987). Flora of the Perth Region. (Western Australian Herbarium, Department of Agriculture, Western Australia). P975.

Parsons, W.T. and Cuthbertson, E.G. (1992). Noxious weeds of Australia. (Inkata Press, Melbourne). P116-118. Photos.

Acknowledgments:

Collated by HerbiGuide. Phone 08 98444064 or www.herbiguide.com.au for more information.