Gazania

Gazania linearis (Thunb.) Druce

Synonyms -

Family: Asteraceae

Names:

Other Names:

Treasure Flower

Summary:

Gazania is a perennial daisy with a tuft of basal leaves. The leaves vary from narrowly elliptic and entire to deeply lobed, 5-10 cm long x 3-20 mm wide, dark green on the upper surface and white-hairy on the lower surface. The colourful flower heads vary from yellow to orange or red and are 5-9 cm across. The outer florets have a spreading petal-like blades 3-4 cm long, while the yellow inner florets are tiny and tubular in shape. The fruits are tiny and are topped by narrow scales and hairs.
Native to southern Africa and introduced as a garden plant, it is now a common garden escape found on roadsides and disturbed areas near settlements and refuse areas. It flowers in winter to early summer.

Description:

Cotyledons:

Two.

First leaves:

Leaves:

Rosette of basal leaves.
Stipules -
Petiole - Yes.
Blade - Narrowly elliptical to narrowly egg shaped. 50-100(180) mm long x 3-20 mm wide. Tip pointed. Sides curved, entire to deeply lobed. Base tapering. Hairless on the upper surface, woolly white hairy underneath.

Stems:

Short, tufted. Stoloniferous.
Flower stem - Leafless.

Flower head:

Single flowers on a stalk.
Flower head (involucre) bracts in several rows, narrowly egg shaped and fused in the lower half.

Flowers:

Daisy like, 50-90 mm diameter.
Outer florets sterile with a yellow to orange to red ligule that is often banded, multicoloured and 30-40 mm long.
Inner (disc) florets bisexual, tubular and 5 lobed.
Ovary -
Calyx -
Perianth - Tubular. Lobed on inner florets.
Sepals -
'Petals' (ligules) - Orange to yellow to red and often banded, 30-40 mm long, spear shaped.
Stamens -
Anthers -

Fruit:

Egg shaped, achene, 4 mm long, hairy with a pappus of narrow scales hidden by hairs.

Seeds:

As above.

Roots:

Taproot. Rhizomes. Forms roots at the nodes of the stolons (stems).

Key Characters:

Leaves have a dark green, hairless upper surface and woolly white hairy under surface.
Involucre bracts fused for half their length.
Colourful flowers.

Biology:

Life cycle:

Perennial herb.

Physiology:

Drought tolerant.
Prefers full sun.

Reproduction:

By seed and stolons.

Flowering times:

Winter to early summer in south west WA.
June to December in WA.

Seed Biology and Germination:

Seed is expected to be short lived.

Vegetative Propagules:

Stolons, rhizomes.

Hybrids:

Hybridizes with Gazania rigens and some naturalised populations are probably horticultural hybrids and varieties.

Allelopathy:

Population Dynamics and Dispersal:

Long distance spread by intentional planting. Medium distance spread by dumping of garden refuse and movement of rhizomes, stolons and seeds by earthmoving equipment. Local spread by stolons, rhizomes and to a minor extent by seed.

Origin and History:

Native to South Africa.
Introduced as an ornamental.

Distribution:

Gazania linearis ACT, SA, VIC, WA, NZ and USA.
Gazania rigens NSW, NT, QLD, SA, TAS, VIC, NZ and possibly WA.

Blue = Gazania linearis. Red = Gazania rigens
Courtesy Australia's Virtual Herbarium.

Habitats:

Common on disturbed sites around settlements and at refuse sites where garden waste is dumped.
Coastal areas.

Climate:

Cool temperate, warm temperate, Mediterranean.

Soil:

Sand and well drained soils.

Plant Associations:

Significance:

Beneficial:

Ornamental and widely cultivated

Detrimental:

Minor environmental weed, mainly of roadsides and other disturbed areas.
There is conflicting information on the species or hybrids that are weedy.

Toxicity:

Not recorded as toxic.

Symptoms:

Treatment:

Legislation:

None.

Management and Control:

Grazing normally provides control.
It is relatively tolerant to occasional mowing or slashing.
Increasing shade levels reduces it.
It is difficult to hand weed because all the stem and rhizome material must be collected and destroyed.

Thresholds:

Eradication strategies:

Use a fork for hand weeding to ensure the underground rhizome is removed with the plant. Mowing is not effective unless repeated regularly and close to the ground. Grazing normally provides control. Cultivation is effective but rhizomes will transplant in wet conditions.
Spray plants until just wet with a mix of 50 mL glyphosate(450g/L) in 10 L water. In bushland areas use 4 g of Lontrel®750 plus 25 mL Pulse® in 10 L water to reduce damage to companion plants. 200 g/ha of Lontrel®750 plus 0.25% wetting agent can be used for roadside and overall spraying. The best time to apply herbicides is in autumn or spring, but good results can usually be achieved any time the plants are actively growing.

Herbicide resistance:

None reported.

Biological Control:

Related plants:

Gazania rigens is a very similar species that occurs in the eastern states and in Albany and Gillingarra in WA. The feature which distinguishes Gazania from most other daisies is the white woolly hairs on the under surface of its leaves.

Plants of similar appearance:

Arctotis (Arctotis stoechadifolia) has silvery foliage and brick red, purple orange or yellow flowers. The involucre bracts are free which distinguishes it from Gazania whose involucre bracts are fused into a tube.
Capeweed (Arctotheca calendula) has yellow flowers with a dark centre and free involucre bracts. Like Gazania it also has leaves with a white woolly under surface. It has central black rather than yellow tubular florets.
Flatweed (Hypochoeris radicata) doesn't have woolly white hairs on the underside of the leaves.
Catsear (Hypochoeris glabra) doesn't have woolly white hairs on the underside of the leaves.
Dandelion (Taraxacum officinale) doesn't have woolly white hairs on the underside of the leaves.
False Sowthistle (Reichardia tingitana) doesn't have woolly white hairs on the underside of the leaves.
Variable Groundsel (Senecio condylus was S. lautus) is a native and has yellow flowers with a yellow centre and doesn't have woolly white hairs on the underside of the leaves.
Everlastings don't have woolly white hairs on the underside of the leaves.

References:

Bodkin, F. (1986). Encyclopaedia Botanica. (Angus and Robertson, Australia).

Blood, K. (2001). Environmental weeds: a field guide for SE Australia. (CH Jerram & Associates, Australia). P176. Photos.

Everist, S.L. (1974). Poisonous Plants of Australia. (Angus and Robertson, Sydney).

Harden, Gwen J. (1991). Flora of NSW. (Royal Botanic Gardens, Sydney). Volume 3. P319. Diagram. (Has Gazania rigens)

Hussey, B.M.J., Keighery, G.J., Cousens, R.D., Dodd, J. and Lloyd, S.G. (2007). Western Weeds. A guide to the weeds of Western Australia. (Second Edition). Plant Protection Society of Western Australia, Perth, Western Australia. P98. Photo.

Lazarides, M. and Cowley, K. and Hohnen, P. (1997). CSIRO handbook of Australian Weeds. (CSIRO, Melbourne).

Moore, J.H. and Wheeler, J.R. (2008). Southern Weeds and their Control. (Second Edition). Department of Agriculture and Food Western Australia. P Photos.

Paczkowska, G. and Chapman, A. (2000). The Western Australia flora: a descriptive catalogue. (Wildflower Society of Western Australia (Inc), the Western Australian Herbarium, CALM and the Botanic Gardens & Parks Authority). P162.

Wheeler, Judy, Marchant, Neville and Lewington, Margaret. (2002). Flora of the South West: Bunbury - Augusta - Denmark. (Western Australian Herbarium, Bentley, Western Australia). P507. Diagram.

Acknowledgments:

Collated by HerbiGuide. Phone 08 98444064 for more information.