Quick Facts

Quick facts

• Originally from Europe and the Mediterranean area, Saffron Thistle (Carthamus lanatus) is one of the most widespread thistle in Australia.
• It is a stiff stout spiny annual to 1 metre tall, with spiny leaves, yellow flowers heads surrounded by spines, spread be seeds.
• It is highly competitive with cereal crops and establishes in degraded pastures.
• It reduces the quality of wool and in dense patches restricts stock movement.
• The seed is not wind dispersed, most seed falls close to the plant, with some spread by attaching to animals.
• Spread further by vehicles and machinery and in agricultural produce.
• Can be controlled with herbicides and mechanical means and cultivation.

What Does It Look Like?

What is it?

Saffron Thistle (Carthamus lanatus) is an erect annual stiff spiny herb, hairless or with few hairs, growing to 1 m high, usually with a single ribbed stem which has many branches in the upper half. Spiny leaves do not have a leaf stalk and their base clasps the stem. Its first leaves rosette leaves are whorled radiating from a central point  more or less flat on ground, up to 200 mm long, deeply divided with broad lobes at their ends, each lobe ending in a short stout spine. Its stiff stem leaves are smaller, up to 110 mm long and 50 mm wide, turned downwards, very rigid and armed with many stout spines.

The flowers are yellow to cream-yellow, arranged in dense clusters of flower-heads (capitula) and each flower-head is solitary at the end of branches, 15–35 mm diameter and 20–25 mm long, surrounded by bracts (leaf-like organs surrounding the flower-heads) and are rigid and spine-tipped. Each flower head produces 10 to 16 seeds.

The fruits or 'seeds' (cypselas) are pale to brownish-grey, 3-8 mm long, with a four-angled base, sometimes with a tuft (pappus) of stiff bristles at the apex (end) and sometimes without (Parsons & Cuthbertson 2001; VicFlora 2016). Flowers spring.

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

Flower colour

Yellow

Growth form (weed type/habit)

Herb

Where it currently grows? Preferred habitat

Saffron Thistle often grows on disturbed sites of low fertility in areas receiving 300 to 600 mm of annual rainfall, but can grow in areas of higher rainfall. It occurs as a weed in cultivated paddocks, poor pastures and neglected areas, but is rarely found in better rainfall areas where pasture competition restricts its development. It tolerates low nutrient concentrations better than any other thistle. Establishment is most likely in areas that have been over grazed or affected by drought (Parsons & Cuthbertson 2001).

Are there similar species?

Three additional species of Carthamus are known to occur in Australia: Carthamus tinctorius  (Safflower), Carthamus dentatus  (Toothed Thistle), and Carthamus leucocaulos (Glaucous Star Thistle) (APC 2021).

Saffron Thistle can be distinguished from the above species by its yellow flowers and deeply divided leaves.

Carthamus dentatus  (Toothed Thistle), and Carthamus leucocaulos (Glaucous Star Thistle) are easily distinguished by their pale violet to pinkish purple flowers.

Glaucous Star Thistle can be further separated from the three other species by having a white to greyish bloom on the stems (Walsh & Entwistle 1999).

Carthamus tinctorius  (Safflower) can be distinguished by its bright orange to yellow flowers and more or less entire leaves, compared to the deeply lobed leaves of Saffron Thistle. .

Why Is It A Weed?

What are its impacts?

Saffron Thistle (Carthamus lanatus) is a weed of agriculture, roadsides, abandoned and degraded areas.

Agriculture: A common weed of agriculture (cropping and pastures) and also widespread in rangelands. Saffron Thistle leaves have little fodder value but in contrast, its seeds are high in oil and protein and are readily eaten by sheep and some other animals. It often occurs in dense patches, its sharp spines restricting stock movement and injuring grazing animals, particularly around the eyes and mouth. The seeds and heads also cause vegetable fault in wool, reducing it's quality. In cropping, competition reduces yield and the hard stems increases wear and tear on harvesting machinery. Seeds and broken plant parts also contaminate wheat (Parsons & Cuthbertson 2001). The plant matures with cereal crops and seed is harvested with the grain, and this is one of the main methods of spread. Dry seeds tangle in wool. Wheat contaminated with saffron thistle seed is liable to dockage (DPIPWE Tasmania (2019).

Native ecosystems: It may invade degraded open native vegetation or native grassy areas, or disturbed sites with-in intact vegetation. Occurs in open woodlands, grasslands and conservation area and is regarded as an environmental weed Australia wide. Does not normally invade healthy dense vegetation

Urban areas: A weed of roadsides and waste places especially in poorer or degraded soils.

How does it spread?

The seed of Saffron Thistle is not dispersed by wind and normally falls to the ground close to the parent plant. However, the stiff bristles on the seed assist it to stick to clothing, wool and fur. Seed is also transported in mud stuck to implements and vehicles. The dried seed heads also tangle in the wool of sheep and sometimes the whole plant breaks off at the base and is carried along by the wind as a 'tumble-weed' (Parsons & Cuthbertson 2001). Seeds are spread by machinery and vehicles when soil with seed attaches.  Also spread along roadsides via graders and movement of soils and gravels.

What is its history in Australia?

Saffron Thistle's early history in Australia is obscure. A plant called Carthamus is listed growing in the colony of New South Wales in 1803 with a comment 'scarce' (King 1803). The first record identified to species level is from the Grampians, Victoria in 1872 (AVH 2021). In 1895 it was listed as in the 10 most important weeds in New South Wales. It was probably introduced to Australia as a source of dye, being confused with the closely related Safflower (Parsons & Cuthbertson 2001).

How To Manage It?

Best practice management

Saffron Thistle (Carthamus lanatus) can be controlled by mechanical and chemical means. Good weed hygiene prevents spread of seed on machinery and vehicles. The recommended control for Saffron Thistle is a rotation of a 2-3 years cropping phase followed by pasture.

Chemical control: There are various herbicides available for effective chemical treatments. Control is often difficult because there are a range of plants at different growth stages. Spot spray for smaller patches and boom spray for larger areas. Seedlings which emerge in the crop can be controlled with herbicide (Parsons & Cuthbertson 2001). For information on herbicide treatments please see: DPIPWE Tasmania (2019); DPI NSW (2019); HerbiGuide (2021); Parsons & Cuthbertson( 2001); Tamar Valley Weed Strategy (2015).  Please check the Australian Pesticides and Veterinary Medicines Authority for chemical information http://www.apvma.gov.au 

Non-chemical control: Physical control: Single plants or small populations can be removed by hand or chipping out if recently new to an area.  However, not normally practical as this species seems to occurs in larger numbers than one or few individuals.

Does it have a biological control agent?

NO

When does it grow? (lifecycle/growth calendar)

In Australia seeds germinate in autumn or early winter and plants over-winter as rosettes. An erect stem develops in late spring as the rosette leaves die. Flowers are produced in November or early December by which time the whole plant, including the leaves, is very rigid and armed with sharp spines. Seeds ripen in December and January (Parsons & Cuthbertson 2001).

Where Is It Found?

Which states and territories is it found?

Found in all Australian states and territories.

What areas within states and territories is it found?

Saffron Thistle occurs in all states and territories of Australia. It is widespread across many parts of New South Wales, Victoria and South Australia, particularly on the Central Western Slopes and Plains, the South Western Slopes and Plains and in the Riverina of New South Wales, the Wimmera, the Mallee and Northern Districts of Victoria and the cereal belt and northern grazing districts in South Australia. In Queensland it is widespread on the Darling Downs, with scattered occurrences further west and north into the tropics. In the Northern Territory it is recorded from the Alice Springs area to the South Australian border. In Western Australia it is established through the northern and eastern wheat-belt, extending into the grazing country around Kalgoorlie and further north into Meekatharra, Carnarvon and Geraldton regions. In Tasmania occurs in small isolated patches especially around Hobart and scatted to  Devonport. (Parsons & Cuthbertson 2001; AVH 2021).

Where does it originate?

Saffron Thistle is a native of Europe (POWO 2019) the Mediterranean region and western Asia (Parsons & Cuthbertson 2001).

National And State Weed Listings

Is it a Weed of National Significance (WONS)?

NO

Where is it a declared weed?

NT, TAS, VIC

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

Carthamus lanatus

Other scientific names (synonyms)?

• Atractylis lanata (L.) Scop.
• Carduncellus lanatus (L.) Moris
• Carduus lanatus (L.) Brot.
• Carthamus baeticus (Boiss. & Reut.) Nyman
• Carthamus creticus L.
• Carthamus lanatus subsp. baeticus (Boiss. & Reut.) Maire
• Carthamus lanatus subsp. creticus (L.) Holmboe
• Carthamus lanatus var. baeticus (Boiss. & Reut.) Cout.
• Carthamus lanatus var. creticus (L.) Halacsy
• Centaurea cretica (L.) Spreng.
• Centaurea lanata (L.) Lam. & DC.
• Heracantha cretica (L.) Hoffmanns. & Link
• Heracantha lanata (L.) Hoffmanns. & Link
• Kentrophyllum baeticum Boiss. & Reut.
• Kentrophyllum creticum (L.) Tausch
• Kentrophyllum lanatum (L.) DC. & Duby
• Kentrophyllum lanatum var. baeticum (Boiss. & Reut.) Batt.
• Onobroma lanatum (L.) Bluff & Fingerh.
• Phonus lanatus (L.) Hill

Does it have other known common name(s)?

Distaff Thistle, False Star Thistle, Woolly Safflower, Woolly Star Thistle, Woolly Thistle, Yellow Star Thistle