Quick Facts

Quick facts

• False Yellowhead (Dittrichia viscosa) is an erect to spreading, much-branched, aromatic camphor-scented, sticky, soft-wooded perennial sub-shrub or shrub 50–150 cm high, 1 metre wide.
• It produces clusters of yellow flowers in dense flower-heads borne on branches  of the main flowering stems and further flowering branches of these.
• It produces large numbers of seeds and is spreading rapidly along roadsides and walking trails in south-western Western Australia.
• It favours disturbed habitat, like roadside and most degraded land subject to disturbance, and areas particularly after fires.
• Preventing the further spread of False Yellowhead is cheaper and easier than all other control options.
• Control of established infestations can be achieved by physical and chemical means, and should be conducted before flowering occurs in summer.
• If you see this weed, contact your state or territory weed management agency or local council. Do not attempt control without their assistance

What Does It Look Like?

What is it?

False Yellowhead (Dittrichia viscosa) is an erect to spreading, much-branched, aromatic camphor-scented, sticky, soft-wooded perennial sub-shrub or shrub 50–150 cm high, 1 metre wide with many glandular and non-glandular hairs. Leaves are without a leaf stalk, 25–100 mm long x 8–30 mm wide, linear (very narrow in relation to its length, with the sides mostly parallel) – oblong ( length a few times greater than width, with sides almost parallel and ends rounded) or linear – oblanceolate,  (lance-shaped about 4 times as long as broad, broadest point at the apex) to elliptic (oval-shaped with the ends pinched together), apex acute (sharply pointed; converging edges making an angle of less than 90°), base sub-amplexicaul, (partially stem clasping) margins without teeth or finely toothed with teeth pointed forward or not. Leaves are pubescent (downy; covered with short, soft, erect hairs ) with glandular and non-glandular hairs. Leaves arranged alternate on the branches

The flower heads are yellow daisy-like clustered in heads, in pyramidal panicles (an indeterminate inflorescence in which the flowers are borne on branches of the main axis or on further branches of these), on flower stalks (peduncles) 5–10 mm long. Individual flower heads are 15–20 mm in diameter, are composed of tubular yellow florets (flowers with strap-like petals) 6–8 mm sometimes 12 mm long. A flower head is surrounded by a group of bracts (leaf-like structures), ranging in size from 1.5–8 mm long. The outer bracts are glandular (have glands), hairy particularly on margins. The  inner bracts more or less glabrous (smooth with out hats). After flowering, individual flower heads produce several hairy, one-seeded fruits

The fruits or 'seeds' (cypselas) are about 1.5–2 mm long with about 15–25 bristles at the base (the pappus) (CRC 2003; FloraBase), pappus 5.5–6.5 mm long (VicFlota 2016)

For further information and assistance with identification of False Yellowhead contact the herbarium in your state or territory.

Flower colour

Yellow

Growth form (weed type/habit)

Shrub

Where it currently grows? Preferred habitat

False Yellowhead usually prefers, but is not restricted to, high rainfall areas. It can be found on both clay and sandy soils. In southwestern Western Australia it is found in areas of medium to high rainfall (i.e. where rainfall exceeds 400 mm per year). It is more reliant on moisture than the closely related Stinkwort (Dittrichia graveolens), which is a weed of grazing land and roadsides of much of southern Australia. In southwestern Western Australia nearly all records of False Yellowhead are from highly disturbed sites: road verges ), firebreaks  and walking trails. Of the three records from bushland, all are from disturbed sites in swamps (Lake Seppings, Mount Manypeaks, and a creek line and swamp at Emu Point) (CRC 2003; DPI).

Are there similar species?

Similar to a related annual species, Dittrichia graveolens (Stinkwort)

Why Is It A Weed?

What are its impacts?

False Yellowhead (Dittrichia viscosa) is on the Alert List for Environmental Weeds, a list of 28 non-native plants that threaten biodiversity and cause other environmental damage. Although only in the early stages of establishment, these weeds have the potential to seriously degrade Australia's ecosystems (CRC 2003). A weed of roadsides, railways and disturbed areas.

False Yellowhead, like Stinkwort (Dittrichia graveolens), can cause health problems in humans and animals. In humans the oil on the leaves and stems causes contact dermatitis, resulting in itching and blistering skin especially if handled when in flower, with some people are allergic to the aromatic oils.

Agriculture: Taints milk and meat but not usually grazed by stock. May not impact well managed pastures but could invade bare areas, or degraded and poorly managed pastures.

Native ecosystems: Infestations of False Yellowhead would detract from the aesthetic and natural values of bushland and could reduce its tourism appeal. The costs of management (e.g. clearing from railway lines or walking trails) would also be significant (CRC 2003).

Urban areas: Known to invade park and garden in Western Australia, and a weed of roadsides.

How does it spread?

False Yellowhead spreads by seed. Seed dispersal is aided by the hairy pappus, an arrangement of hairs at the top of the seed, which catches the wind or can assist flotation. Seed can also be spread during soil movement (e.g. in road making or road grading) or when attached to machinery (CRC 2003).

What is its history in Australia?

Originally from the Mediterranean region, it is not clear how False Yellowhead was introduced to Australia but it may be a garden escape. It was first recorded in Albany in 1955 and has since spread throughout southern Western Australia. It is occasionally found in swamps but mainly occurs in highly disturbed areas such as roadsides, railway lines, fire breaks and walking trails (CRC 2003).

How To Manage It?

Best practice management

False Yellowhead (Dittrichia viscosa) can be controlled by physical and mechanical means, and herbicides. Older plants with flowers treated with herbicide may produce seed, so may need to be treated by mechanical means. Plants with flowers that slashed or mown may also produce seed and need to be bagged and dumped, or put in heaps and burned to prevent seed production and subsequently dispersal and spread in the area. Timing is important to kill or manage plants to prevent seed set. Seeds are viable for extended periods able to endure many years of dormancy if deprived of light. Because there are relatively few False Yellowhead infestations, it can be eradicated before it becomes established, and it is highly recommended that any new outbreaks should be reported immediately to your state or territory weed management agency or local council. Do not try to control False Yellowhead without expert assistance. Control effort that is poorly performed or not followed up can actually help spread the weed and worsen the problem (CRC 2003).

Chemical control: False Yellowhead can be sprayed with herbicide. In Western Australia spraying some roadside infestations of False Yellowhead has been encouraging with good kill rates helped by the clumping of plants, although it has been important to spray before seed set. Occasionally, applying herbicide to the stump has been used to treat larger plants. (CRC 2003)

Please see the Australian Pesticides and Veterinary Medicines Authority for chemical information http://www.apvma.gov.au 

Non-chemical control: Physical control: Before False Yellowhead flowers, isolated plants or small patches can be hand-pulled (wearing gloves), or use a fork to remove plants, minimising soil disturbance. Follow-up manual weeding of previously sprayed patches of any False Yellowhead plants is recommended to minimising disturbance to the soil and reducing the likelihood of germination of False Yellowhead weed seeds in the soil seedbank.

Does it have a biological control agent?

NO

When does it grow? (lifecycle/growth calendar)

In Australia, flowering takes place between December and April. Germination generally takes place following rainfall and can be quite prolific when fire or mechanical disturbance creates bare ground. Under laboratory conditions, False Yellowhead seeds have been shown to undergo a deep dormancy, which is broken by a lack of light. Seeds of the closely related Stinkwort (Dittrichia graveolens), are viable for about three years (CRC 2003).

Where Is It Found?

Which states and territories is it found?

VIC, WA

What areas within states and territories is it found?

False Yellowhead is well established on the south coast of Western Australia, having spread from Albany to Mount Barker and Denmark, some 40 km to the north and west respectively. There are established remote populations at Walpole-Peaceful Bay, 60-80 km west of Albany, and at Mount Manypeaks, 60 km east of Albany. An isolated population has also been recorded on a train track at Yarloop some 350 km north-west of Albany and 125 km south of Perth. This infestation was possibly spread by seed carried by a train (CRC 2003).

It has also been recorded Victoria naturalised in a degraded Eucalyptus camaldulensis woodland on a golf course in Glenroy, a suburb in northern Melbourne VicFlora (2016)

False Yellowhead has the potential to be a serious environmental weed, particularly in south-western Western Australia and areas of similar climate in southern and eastern Australia (CRC 2003).

Where does it originate?

False Yellowhead is native to southern Europe (including France, Portugal, Spain, Greece, Albania, Bulgaria and Italy) through to Turkey and the Middle East (Israel, Jordan, Lebanon, Syria and Cyprus). It is also found in northern Africa (Algeria, Egypt, Libya, Morocco and Tunisia) (CRC 2003; GRIN).

National And State Weed Listings

Is it a Weed of National Significance (WONS)?

NO

Where is it a declared weed?

VIC, WA

Government weed strategies and lists – Weeds Australia

Is it on the National Alert List for Environmental Weeds?

YES

Government weed strategies and lists – Weeds Australia

Is it on the Agricultural Sleeper List?

NO

Government weed strategies and lists – Weeds Australia

Names And Taxonomy

Main scientific name

Dittrichia viscosa

Other scientific names (synonyms)?

Cupularia viscosa (L.) Gren. & Godr.

Erigeron viscosus L.

Inula viscosa (L.) Aiton

Does it have other known common name(s)?

Aromatic Inula, Sticky Fleabane