Quick Facts

Quick facts

• Originally  from western Europe, the Mediterranean region and north Africa to central Asia, Skeleton Weed (Chondrilla juncea) is a biennial to perennial herb that can grow up to 1.3 metres high
• Produces a rosette of lobed leaves first, followed by erect much-branched, wiry, almost leafless green stems and all parts exude thick milky latex when cut or broken.
• Stems produce many yellow daisy flowers producing thousands of seeds with fluffy white parachutes attached.
• It reproduces and spreads by seed and regrowth from roots and root fragments.
• It is one of the worst perennial weeds of cultivation in Australia, being a serious crop weed especially in wheat growing regions, and once established can be difficult to eradicate.
• It has the ability to reduce crop yields by competing for water and nitrogen, and can seriously interfere with and make harvesting difficult due to its tangled mass of wiry stems.
• Cultivation of infested areas should be avoided,  due to the regenerating properties of cut underground stems as the chopped roots have the ability to re-shoot and establish new plants within and beyond infested areas.
• Integrated long term control is required with herbicides and slashing or mowing, and grazing.

What Does It Look Like?

What is it?

Skeleton Weed (Chondrilla juncea) is a biennial (in its native range) or sometimes a perennial herb in Australia growing up to 1.3 m high with upright, wiry, often tangled, stems. It has a deep taproot (to a depth of 3 m or more) and also has creeping roots (lateral roots from the branched taproot) that can form new plants. The first leaves produced are variable basal rosette leaves (circular cluster), with a petiole (leaf stalk), laying more or less flat on the ground. Rosette leaves are short-lived, oblanceolate (lance-shaped with widest point at the apex), lobed-leaves to deeply toothed, with lobes or teeth pointing towards the base, apex (tip of leaves) obtuse (blunt or rounded; converging edges making an angle of more than 90°). Rosette leaves are 40–200 mm long, 10–50 mm wide, more or less glabrous (without hairs). A single main stem arises from the centre of the rosette, with plants becoming openly much-branched above. This green stem is slender, tough, ribbed and produces milky white latex (this thick, milky sap also occurs in the leaves and other parts of the plant). The cauline (stem) leaves, if present, are few, inconspicuous and widely spaced, without a leaf stalk, up to 100 mm long but mostly much smaller to10 mm.

The flower heads are numerous yellow daisy-like narrow flower-heads, which are solitary, or in clusters of 2 to 3 or occasionally up to 5, in axils (between stem and leaf) of reduced leaves. These heads are widely spaced along the upper stems, shortly stalked or without a stalk. The flowers heads are thin, comprised of 7-15 small yellow ray flowers (florets) and each of these 'petal' like florets is strap shaped, 7-10 mm long, squared at the end and minutely toothed, are surrounded by a group of bracts (leaf-like structures) 9–13 mm long; inner bracts 7–9, linear-lanceolate, glabrous (without hairs) to tomentose (with a dense covering of short, woolly hairs), with prominent midrib and dark apex. Flowers late spring–autumn

The fruits or 'seeds' (cypselas) are one-seeded, cylindrical, 8-10 mm long (including a conspicuous 4-6 mm long narrow beak or column), ribbed, whitish to dark brown, hairless, barbed toward the apex by small tooth-like projections, and topped by a 5-7 mm long white parachute-like pappus (ring) of numerous fine spreading silky hairs (McVean 1966; Cooke 1986; Lander 1987; Lamp & Collet 1989; Murray 1992; Felfoldi 1993; Panetta & Dodd 1995; Holm et al. 1997; Jeanes 1999; Parsons & Cuthbertson 2001; Fletcher et al. 2003; Sainty & Associates 2003; Western Australian Department of Agriculture and Food 2005a, 2007a; Richardson et al. 2006).

Narrow-leaf, broad-leaf and intermediate-leaf forms of Skeleton Weed are recognised in Australia, primarily based on the shape of the basal rosette leaves. The leaves die early back in the flowering period and plants are then virtually leafless over summer, hence the common name Skeleton Weed (Panetta & Dodd 1995; Holm et al. 1997; Parsons & Cuthbertson 2001; Sainty & Associates 2003).

For further information and assistance with identification of Skeleton Weed, contact the herbarium in your state or territory.

Flower colour

Yellow

Growth form (weed type/habit)

Herb

Where it currently grows? Preferred habitat

Skeleton Weed grows in temperate, sub-humid and semi-arid open scrub-lands occurring in dry situations on well-drained sandy to moderately textured, often richer, soils, and does not readily establish on heavy textured soils (Parsons & Cuthbertson 2001). It grows in cultivated fields and crops, especially cereal crops and frequently on fallows, being a serious weed in wheat belt areas with more than 350 mm annual rainfall, it also occurs in pastures, orchards, vineyards, gardens, waste and disturbed sites such as quarry and mine sites, roadsides, railway yards and along railway lines, and on riverbanks. Skeleton Weed has also invaded native ecosystems: mallee shrubland, grasslands, woodlands, grassy eucalypt woodland, scrub heath and coastal sandhills (McVean 1966; Cooke 1986; Panetta & Dodd 1995; Holm et al. 1997; Jeanes 1999; Parsons & Cuthbertson 2001; Western Australian Department of Agriculture and Food 2005a; Richardson et al. 2006).

Are there similar species?

In the vegetative state (when flower stems are absent), Skeleton Weed has very variable rosette leaves that can be deeply lobed to only toothed, thus resembling a number of other weeds that have rosettes of lobed or toothed leaves, such as Cat's-ears (also known as Flatweed; Hypochaeris radicata), hawksbeards (Crepis spp.), Hairy Hawkbit (Leontodon saxatilis) [as Leontodon taraxacoides], Dandelion (Taraxacum cygnorum) [as Taraxacum officinale], Willow Leaf Lettuce (Lactuca saligna), Prickly Lettuce (Lactuca serriola), Capeweed (Arctotheca calendula) and various species of crucifers (family Brassicaceae). Some of these rosette look-alikes also produce branched flowering stems, yellow flowers and/or milky latex. However, Skeleton Weed can be distinguished by a combination of features:

• its extensive branched root system
• skeletal appearance (being highly branched with almost bare wiry stems)
• milky latex in all plant parts
• basal rosette leaves that are more or less hairless, soon wither, and have teeth or lobes that point back towards the plant stem
• no leaves or few or small leaves on flowering stems
• all florets yellow with a 'petal' (strap-like ligule)
• bracts (modified leaves) around flower-heads in 2 rows (the outer being minute), and
• cylindrical fruits with a conspicuous hair-like beak/column that is topped by a ring (pappus) of white bristles (Meadly 1963; Panetta & Dodd 1995; Holm et al. 1997; Sainty & Associates 2003; Western Australian Department of Agriculture and Food 2005a; Richardson et al. 2006).

Skeleton Weed is also related to Chicory (Cichorium intybus), which has purplish sky-blue or rarely white flowers, and Rough Sowthistle (Sonchus asper), which has numerous stem leaves that have spiny, wavy margins (Holm et al. 1997; Richardson et al. 2006).

A Skeleton Weed look-alike key and similar species guides, such as those provided by O'Neil (1961), Fletcher et al. (2003) and the Western Australian Department of Agriculture and Food (2006), may be used to help identify the plant.

Why Is It A Weed?

What are its impacts?

Skeleton Weed (Chondrilla juncea) can form tall dense stands or thickets, and is mainly a weed of cultivated areas, paddocks, orchards, gardens, roadsides, open wasteland and other disturbed sites. It is a serious invader of pastures and cropland, particularly in cereal growing areas in the southern states with major impacts occurring in wheat-growing areas of south-eastern Australia (Cooke 1986; Panetta & Dodd 1995; Parsons & Cuthbertson 2001; Sainty & Associates 2003). Skeleton Weed is a potential threat to large areas of the wheat belt in Western Australia (and other agricultural areas), but eradication efforts have helped to prevent the establishment of large populations so far (Hussey et al. 1997).

Agriculture: Skeleton Weed is a serious weed of cultivation causing substantial losses in cereal crop yield, especially when severe infestations compete with crops. It crowds out crops and is a strong competitor for moisture and nutrients, especially nitrogen (particularly before the crop is sown and in the early stages of crop growth). In Australia and Argentina it is a major problem of wheat fields and can reduce yields by 80% (CABI 2021). Affected crops include Cluster Clover, Cocksfoot, Japanese Millet, Lucerne, Ryegrass, Strand Medic, wheat, and White Clover. The tough wiry stems that often form tangled masses interfere with harvesting equipment by tangling within machinery, choking headers and making harvesting difficult. They can cause significant wear and tear to harvest machinery as well as causing delays through mechanical breakdowns and jamming machinery. Before effective control measures were developed, Skeleton Weed had prevented the harvesting of heavily infested wheat crops leading to cereal cropping being abandoned in many areas. It can also compete and interfere with fodder plants in sown pastures, as well as unimproved pastures weakened by drought or overgrazing (McVean 1966; Lander 1987; Felfoldi 1993; Panetta & Dodd 1995; Holm et al. 1997; Parsons & Cuthbertson 2001; Sainty & Associates 2003; Western Australian Department of Agriculture and Food 2007a). As well as the financial losses resulting from reduced crop yields, there are also costs associated with control and management programs which aim to save farmers from potential greater losses. Skeleton Weed has its greatest economic impact in the cereal phase of the crop-pasture rotation (Panetta & Dodd 1995). It is drought tolerant and can provide useful grazing as the rosette leaves have value as sheep fodder and produce excellent fat lambs. However, once the stem grows and rosette leaves, die it loses much of this value and infested areas yield little fodder in the autumn or winter months (Felfoldi 1993; Panetta & Dodd 1995; Parsons & Cuthbertson 2001; Sainty & Associates 2003). The fibrous flowering stem has been known to cause choking and loss of condition when eaten by dairy cattle (Currie 1936, in Panetta & Dodd 1995).

Native ecosystems: Skeleton Weed sometimes invades native vegetation (including woodlands, grassy eucalypt woodland, open mallee scrub, mallee shrubland, scrub heath, grasslands and coastal sandhill communities), but generally only when areas have been subjected to drought or overgrazing (McVean 1966).

Urban areas: A weed of roadsides and waste place especially in agricultural areas and regional towns.

How does it spread?

Skeleton Weed spreads by seed, pieces of root or sections of underground stems, and by forming new rosettes from tap and lateral roots. Cultivation is a major cause of local spread as underground stems and roots are cut through by farm machinery and equipment and pieces are dragged to uncontaminated areas. These pieces produce fibrous roots and new plants when adequate moisture is available. Continual cropping without stock enhances the establishment and dispersal of plants, as continual fallowing produces a seed bed as well as spreads root pieces. Seed production is prolific, and a single plant can produce 27,000 seeds per year. Seeds are dispersed by wind and aided by a relatively large pappus and small scales and tooth-like projections on the seed apex help the seed to attach to wool, fur, clothing, other fabrics and other materials e.g. sacks. Seeds may also catch in the crevices of, or mud on, machinery, vehicles, railway trucks and boots and may possibly be transported by water. Contaminated wool has been a major means of dispersal in Australia, as well as contaminated grain, hay and chaff (particularly during times of drought when there is large-scale movement of fodder). Road and rail transport are also important, with seeds sticking in mud, tarpaulins and crevices (Lamp & Collet 1989; Felfoldi 1993; Panetta & Dodd 1995; Holm et al. 1997; Parsons & Cuthbertson 2001; Sainty & Associates 2003).

What is its history in Australia?

Skeleton Weed was accidentally introduced to Australia some time prior to 1910, presumably as seed and probably from southern Europe with vine stocks or with animal fodder or bedding. Although it was known to grow at Coursing Park near Wagga Wagga, New South Wales in 1913, it was not identified until 1917 from a specimen collected from infested paddocks at Marrar. It spread rapidly from this area, and much of the Riverina had become heavily infested by 1930 (Panetta & Dodd 1995; Parsons & Cuthbertson 2001; Western Australian Department of Agriculture and Food 2005a).

Skeleton Weed was introduced to Canberra during the 1914-1915 drought (Burbidge & Gray 1979). It was established in Victoria by 1935 (probably spread mostly in fodder from New South Wales and occurring throughout the Victorian Mallee by the 1940s), was in South Australia by 1947, reached the Darling Downs in southern Queensland in 1956, and by 1963 the first patch was found in Western Australia at Ballidu (Cooke 1986; Panetta & Dodd 1995; Parsons & Cuthbertson 2001). It has become an important and widespread weed in southern Australian wheat belt areas with more than 350 mm annual rainfall (Parsons & Cuthbertson 2001).

How To Manage It?

Best practice management

Skeleton Weed (Chondrilla juncea), once established, can be difficult to eradicate. Cultivation of infested areas should be avoided, especially in cultivated crops, due to the regenerating properties of cut underground stems as the chopped roots have the ability to re-shoot and establish new plants. It is also important to prevent plants from seeding. Preventing further spread using quarantine and restriction on the sale and movement of produce and machinery from affected areas will reduce the risk of spread. Farm equipment, vehicles and other objects should be checked and cleaned to prevent the movement of seed or root pieces to uninfested areas. Control is assisted through regular surveillance and public awareness, especially amongst farming communities. Infested and treated areas require regular monitoring (Parsons & Cuthbertson 2001; Fletcher et al. 2003; Western Australian Department of Agriculture and Food 2006, 2007a, undated).

Chemical control:  The deep and extensive roots of Skeleton Weed make it difficult to control with chemical herbicides and successful control can only be achieved with multiple applications. Chemical management, using herbicides often in conjunction with cropping is a valuable control tool (Parsons & Cuthbertson 2001; Western Australian Department of Agriculture and Food 2005b, 2006, 2007a, 2007b, 2007c, 2007d). Please see DPIRD (2021) and the Australian Pesticides and Veterinary Medicines Authority for chemical information http://www.apvma.gov.au.

Non-chemical control: Physical control:  Small infestations of Skeleton Weed can be controlled by hand pulling when the soil is wet. This must be done several times per year for several years but the deep root system may resprout. Plant roots can grow to 1 metre in a single season eventually reach 2-3 meters deep.

Does it have a biological control agent?

YES

When does it grow? (lifecycle/growth calendar)

Seeds germinate after autumn rains and the young plants form rosettes with a developing taproot during winter. In spring, about September, an erect stem is produced from the rosette centre. As the plant grows, the rosette leaves die leaving a virtually leafless much-branched wiry plant that flowers from late spring but mainly through summer and autumn. Seeds are also produced throughout summer and autumn. In autumn, the aerial growth dies and is easily broken off at ground level. One to three new rosettes develop from each rootstock (taproot) in autumn to early winter and these produce flowering stems and flowers in the following spring to summer. New rosettes are also formed on lateral roots, thus increasing spread of the plant. Cultivation at almost any time of the year will stimulate production of new rosettes from the taproot and severed root fragments. Under drought conditions, which limit aerial growth, new rosettes may be produced whenever effective rain is received (Felfoldi 1993; Parsons & Cuthbertson 2001).

Where Is It Found?

Which states and territories is it found?

ACT, NSW, QLD, SA, VIC, WA

What areas within states and territories is it found?

Skeleton Weed is found throughout most of south-eastern Australia (from south-eastern Queensland, through much of New South Wales (especially in the east), the Australian Capital Territory and Victoria (especially in the north; mainly across drier inland areas) into south-eastern South Australia), as well as occurring in south-western Western Australia (Geraldton area to Esperance). It is a serious weed of wheat-cropping areas on the Australian mainland, including almost the entire cereal-growing areas of New South Wales and Victoria (McVean 1966; Burbidge & Gray 1979; Cooke 1986; Lander 1987; Murray 1992; Panetta & Dodd 1995; Jeanes 1999; Western Australian Department of Agriculture and Food 2005a; Western Australian Herbarium 2007; Tasmanian Department of Primary Industries and Water 2008).

Skeleton Weed has been recorded as an occasional weed in Tasmania (Curtis 1963) and was possibly a temporary crop weed on King or Flinders Island (Baker 2008, pers. comm.). There are currently no known naturalised populations of this plant in Tasmania, but it has been recorded as an occasional contaminant of imported agricultural products there (Tasmanian Department of Primary Industries and Water 2008; AVH 2021).

Not recorded in the Northern Territory (APC 2021; AVH 2021).

Where does it originate?

Skeleton Weed originated in Eurasia and its native range extends from western Europe, the Mediterranean region and north Africa to central Asia. It is now found in central Europe, North and South America, Australia and New Zealand (McVean 1966; Panetta & Dodd 1995; Holm et al. 1997; Parsons & Cuthbertson 2001).

National And State Weed Listings

Is it a Weed of National Significance (WONS)?

NO

Where is it a declared weed?

SA, TAS, VIC, WA

Government weed strategies and lists – Weeds Australia

Is it on the National Alert List for Environmental Weeds?

NO

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

Chondrilla juncea

Other scientific names (synonyms)?

Does it have other known common name(s)?

Rush Skeleton Weed, Rush Skeletonweed, Naked Weed, Gum Succory, Succory