Gorteria

Gorteria personata

Synonyms - Gorteria calendulacea, Gorteria diffusa.

Family: Asteraceae.

Names:

Gorteria is named after the Dutch botanist, David de Gorter.
Personata is from the Latin word 'masked' and probably refers to the seeds that are hidden in the burr.

Summary:

A small, bristly haired, winter growing annual with lobed leaves that are lighter green underneath than on top. It has yellow and brown daisy like flowers with 8-10 'petals' in spring and sharp, spiny burrs with 3-6 seeds.

Description:

Cotyledons:

Two.

Leaves:

Alternate.
Stipules -
Petiole - broad, flat.
Blade - dark green on top, lighter underneath, 60-80 mm long x 10-15 mm wide. Stiff hairs on both sides. Edges deeply lobed or slightly lobed near the base. Tapers into petiole.

Stems:

Pale green, cylindrical, much branched, spreading, rough to touch, stiff to woody, up to 200 mm high. Short rigid, white hairs.

Flower head:

One to several flowers in a small head at the ends of branches. Bracts,

Flowers:

Yellow and brown.
Bracts - several rows, thick, hairy, sharply pointed and fused to make a woody spiny burr at maturity.
Florets - 8-10 edge florets, sterile with 'petals'.
6-10 disc florets, dark, tubular, 5 lobed with the outer ones female and the inner ones male.
Ovary -
'Petals' - 8-10, yellow, oblong, 5-10 mm long. Tip has 3 teeth.
Stamens -
Anthers - Yellow.

Fruit:

Woody burr with 3-6 seeds. Long springy spines, which wear into sharp needles.

Seeds:

Small, light brown, 3 angled. Pappus of short bristles inside a papery membrane.

Roots:

Slender taproot with many fibrous laterals.

Key Characters:

Yellow daisy like flowers with spiny, woody burrs.

Biology:

Life cycle:

Annual. One seed in the burr germinates from February to July with the main flush of germination just after the break of the season in May. Flowering starts in August and continues until November. Burrs mature 4-6 weeks after flowering and fall off. The plant dies in summer. Seeds won't germinate for a few months after maturity. In the following season other seeds within the burr may germinate.

Physiology:

Reproduction:

By seed.

Flowering times:

Spring in WA.

Seed Biology and Germination:

Seeds won't germinate for several months after ripening.
Seed may remain dormant in the soil for several years.

Vegetative Propagules:

None.

Hybrids:

Allelopathy:

Population Dynamics and Dispersal:

Spread is by spiny burrs attaching to stock, machinery and footwear. It is not competitive with pasture species.

Origin and History:

South west Africa.
First recorded on a roadside between Miling and Moora in WA in 1964 and has spread along the north western edge of the wheat belt.

Distribution:

WA.
Mingenew to Moora to Meckering.

Courtesy Australia's Virtual Herbarium.

Habitats:

Climate:

Mediterranean, sub-tropical and warm temperate at altitudes up to 700 metres.

Soil:

Sandy and gravelly and granitic soils.

Plant Associations:

Open wood lands and shrub lands.

Significance:

Beneficial:

Palatable.

Detrimental:

Weed of roadsides, railways, watercourses, disturbed areas, lawns, crops, pastures wood lands and shrub lands.
Burrs may contaminate wool but are not common in grazed pasture.
It competes strongly with native plants.

Toxicity:

Not recorded as toxic.

Legislation:

Noxious weed of WA.

Management and Control:

Thresholds:

Eradication strategies:

Mechanically remove isolated plants, collect burrs and burn them.
Restrict stock, vehicle and human access to the areas to prevent spread of burrs.
Larger areas can be sprayed with combination of amitrole, atrazine, paraquat and 2,4-D.

Herbicide resistance:

None reported.

Biological Control:

Related plants:

None.

Plants of similar appearance:

References:

A.P.B. Advisory Leaflet No. 66 (1981)9

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). P98. Photo.

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

Parsons, W.T. and Cuthbertson, E.G. (1992). Noxious weeds of Australia. (Inkata Press, Melbourne). P283-285. Photos.

Acknowledgments:

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