Skeleton weed

Chondrilla juncea L.

Family: - Asteraceae.


Chondrilla is from the Greek chondros meaning gristle and refers to the wiry or gristly stems.

Juncea is from the Latin name for rushes, Juncus, and refers to the rush like stems.

Skeleton weed refers to the skeleton like appearance of the stems.

Other Names:

Gum succory (USA)

Naked weed (USA)

Rush Skeletonweed (USA)


A yellow flowered, wiry stemmed, perennial forb with an extensive root system and rosette leaves with backward pointing lobes.



Two. Oval. Tip round. Base tapered. Short petiole. Hairless.

First leaves:

Oval. Tip round. May have small teeth on edges.


Green but often with a purple tinge. Forms a rosette that tends to die off before the plant flowers in summer. Exudes a white milky sap when broken. Wither and fall off in summer.

Stipules - None.

Petiole - Short winged leaf stalk.

Blade - Light to greyish green. Lobes usually point backwards. Tip round to pointed. Sides toothed. Base tapered. 40-200 mm long by 15-45 mm wide. Older rosette leaves are more deeply lobed than younger ones. Hairless or with a few rigid hairs.

Three forms occur which can only be accurately identified by enzyme tests. In the field, the shape of the tenth or later leaves can usually distinguish them.

Form A - Narrow leaf form has lanceolate leaves, with narrow widely separated lobes, relatively entire margins and a pointed leaf tip.

Form B - Intermediate leaf form has oblong-elliptical with triangular lobes with serrated margins and an acute leaf tip, but not as pointed as in the narrow leaf form.

Form C - Broad leaf form has elliptical leaves, that are slightly indented with lower lobes that are scalloped with relatively entire margins and a spade shaped leaf tip.

Stem leaves - Alternate, smaller, 1-60 mm x 0.5-3 mm, hairless, widely spaced. Edges maybe toothed. Fall off as the plant matures. Occasionally there are no stem leaves.


Greyish green, erect, stiff, wiry, smooth or striped, almost leafless, tangling, solid with pithy core, up to 1250 mm tall and usually 600-900 mm tall. Usually a single stem that is many branched toward the top to form a large panicle. Branches are often tangled. Leafy bract at the base of each branch. Usually has dense downward pointing bristles near the base with the upper parts hairless and smooth or with a few stout hairs. Exudes a white milky sap when damaged.

Flower head:

Narrow cylindrical, 9-13 mm long by 2.5-5 mm wide. At the ends of branches or in leaf axils. Maybe single or in groups of 2-5 heads on a very short stalk or none.


Yellow, bisexual. 9-12 flowers per head, all with 'petals' (ligulate).

Bracts - 7-9, green, slightly tapering, inner bracts that are initially sparsely hairy near the edges and later smooth. Tip usually obtuse. A few, much shorter outer bracts at the base.

Ovary - Receptacle flat, without bracts (naked).

Petals - 'Petals' yellow with white streaks underneath, 10 mm long, strap like, with a square and toothed tip.

Stamens -

Anthers -


Achene. Dark brown to pale, tapering cylindrical, 3-4 mm long (8-10 mm including the beak), 5 angled, longitudinally ribbed, striped and near the tip it is rough to touch and scaly with short pointed outgrowths. Upper scales elongated and fused into a tiny 5 toothed crown around the long, narrow beak that is 4-5 mm long. Pappus at the top of the beak has many rows of silky, bluish white, simple or barbed bristles or hairs that are 5-8 mm long and arise from a cup like base.


Cylindrical, 3-4 mm long. Pale. Striped.


Extensive, long, slender, taproot system, 5-10 mm diameter, often to a depth of over 3 metres. Slender horizontal roots may form 100-150 below the surface. Crown is simple or branched. Exudes a white milky sap when damaged.

Key Characters:

Wiry, almost leafless stems. Yellow flowers. Backward pointing leaf lobes.


Life cycle:

Perennial or biennial rhizomatous herb. Germinates autumn/winter. Forms a rosette about 200 mm wide in winter and develops a long thin taproot up to 1000 mm deep. The rosette tends to die off as wiry stems elongate in spring to form a tangled mass with neighbouring plants. Flowers usually occurs in summer and autumn. Individual flowers are only open for one day. In autumn the stems die back and are easily broken at ground level. 1-3 rosettes then arise from each rootstock in the autumn to flower in spring to summer. Rosettes also form from lateral roots. Cultivation or damage to the roots results in the formation of rosettes from the taproot or root fragments at most times of the year. In Australian conditions individual plants often live for many years.


Optimum conditions for growth include;

High summer temperatures for flower and seed formation.

Summer rainfall or stored soil moisture for seed viability and production.

Autumn break of the season with lowered temperatures and rainfall or soil moisture to encourage seed germination.

Deep, light soils to allow taproot development to avoid drought.

Disturbance to encourage seed germination.

Adequate soil phosphorous and calcium.

Open, unshaded areas with little competition to allow seedling recruitment.


By seed, root stocks and root fragments.

Flowering times:

Summer in SA.

Summer in NSW.

Mainly December to March with sporadic flowers in other months in WA.

Seed Biology and Germination:

Usually white and yellow seeds are sterile and olive green to dark brown seeds are viable.

A single plant can produce 27,000 seeds per year.

Viability is around 80% and depends on good moisture during ripening.

Germinates over a wide range of temperatures from 7-40 degrees C.

Seed is short lived in the field with little carry over from one season to the next.

Most seeds will germinate on the surface and the germination percentage drops with depth of burial to zero at 50 mm depth.

Seedlings are sensitive to competition and shading.

Vegetative Propagules:

Rhizomatous roots.

Regrowth has been recorded from roots severed 1200 mm below ground.


3 forms occur in Australia, the narrow leaf, intermediate leaf and broad leaf form. The broad leaf form is more erect and competitive than the narrow leaf form, which has largely been controlled by an introduced rust. The intermediate form is uncommon.


Population Dynamics and Dispersal:

Seed is spread by wind, as a grain contaminant, by animals (especially sheep) and machinery. The long, barbed, pappus bristles assist with wind dispersal and attachment to wool, fur, fabric, machines and vehicles. Over half the rail wagons entering WA after passing through ripe infestations, thousands of kilometres away, have carried Skeleton weed seed.

Dispersal by water occurs but is not a major form of spread.

Ants may cause minor local spread.

Origin and History:

Mediterranean, North Africa, central Europe to Siberia.

First recorded near Wagga Wagga in 1913.

Established in VIC before 1935.

First recorded in SA in 1947.

In QLD by 1956.

First recorded in WA in 1963.

One plant has been recorded on King Island in TAS.

Introduced to the ACT during the 1914-15 drought.



Eradicated from TAS.



Temperate, Mediterranean, sub humid, semi arid.

Most abundant where the annual rainfall exceeds 350 mm.


Red or brown earths. Well drained sandy to loamy soils.

Uncommon on heavy soils.

Plant Associations:

Wide range.

Open scrub lands.



Fodder, rosette leaves are eaten and may provide valuable forage at certain times of the year when little else is available. Stems are unpalatable.

Source of pollen for honey bees.

Does not host Root Lesion Nematodes (Pratylenchus neglectus or thornei) (Vanstone & Russ, 2001)


Weed of crops causing harvest problems and significant yield losses due to competition for moisture and nutrients (especially nitrogen). Weed of pastures, fallows, roadsides, vineyards and disturbed areas.

Before hormone herbicides cropping was abandoned is many heavily infested areas.


Not recorded as toxic.


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

Management and Control:


Eradication strategies:

Difficult to eradicate because of its extensive root system.

Cultivation may increase the infestation by cutting and spreading root fragments that may form new plants.

Encourage a dense pasture sward. Lucerne is particularly effective in areas suited to its growth. Annual legumes are used in other areas.

Several herbicides provide partial control. Lontrel and picloram are showing the best results for high levels of control. Other hormone herbicides provide control of the rosettes and shallow roots but don't kill the deeper taproot, which normally re shoots.

Use of picloram in combination with a rust fungus is being investigated.

Herbicide resistance:

Biological Control:

Several agents have been released.

For the narrow leaf form a rust (Puccinia chondrillina) provides good control and a gall mite (Aceria chondrillae) has been released.

A gall midge (Cystiphora schmidti) which attacks all forms has also been released.

The bio control agents have resulted excellent control of the narrow leaf form but in many areas the broad leaf form has replaced it. Research is continuing.

Seed harvesting ants consume seed but have little impact because of the short lived nature of the seed.

Related plants:


Plants of similar appearance:

Dandelion (Taraxacum officinale) is very similar in the rosette stage.

Flatweed and Smooth Catsear (Hypochoeris spp.) also have yellow flowers, hairless stems and similar rosettes but the lobes tend not to be backward pointing.

Bushy Starwort (Aster subulatus) doesn't have distinct backward pointing lobes on the leaves and the flowers are white to pink and turn bluish on drying.

Capeweed (Arctotheca calendula) has a light underside and darker upper surface on the leaf.


Fleabane (Conyza spp.)

Hawkbit(Leontodon taraxacoides)

Indian Hedge Mustard (Sisymbrium orientale)

Ox tongue (Helminthotheca echioides)

Prickly Lettuce (Lactuca serriola)

Prickly Sow Thistle (Sonchus asper)

Rapistrum (Rapistrum rugosum)

Saffron Thistle (Carthamus lanatus).

Slender Thistle (Carduus spp.)

Skeleton Weed (Chondrilla juncea) has backward pointing leaf lobes.

Sow Thistle (Sonchus oleracea)

Wild Radish (Raphanus raphanistrum)

Wild Turnip (Brassica tournefortii)


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Gilbey, D. (1989). Identification of weeds in cereal and legume crops. Bulletin 4107. (Western Australian Department of Agriculture , Perth). P52. Photos.

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Parsons, W.T. and Cuthbertson, E.G. (1992). Noxious weeds of Australia. (Inkata Press, Melbourne). P264-270. Diagrams. Photos.

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