Quick Facts

Quick facts

• African Rue (Peganum harmala) is a stiff-stemmed, perennial herb or shrubby plant, growing from 30 to 80 cm high, with smooth stems and leaves 2–5 cm long, somewhat succulent, bright green that are deeply divided in to linear sections with white to cream flowers.
• Occurring in temperate, semi-arid and arid regions, predominantly in south-eastern South Australia with some records from drier areas in Victoria and New South Wales.
• It is drought and salt tolerant.
• Its effect on native species is unknown, but it could potentially impact significantly on native plant communities is semi-arid environments.
• Although toxic, it appears to be highly unpalatable to stock.
• Difficult to control once established due to deep roots, chemical control is more effective with repeated spraying as required until the plants are killed.

What Does It Look Like?

What is it?

African Rue (Peganum harmala) is an erect, much-branched, smooth, stiff-stemmed perennial herb or shrubby plant, growing from 30 to 80 cm high. The stems are hairless and slender, and arise from short, long-lived underground stems, with woody rootstock. The leaves are alternately arranged, 2–5 cm long, somewhat succulent, bright green in colour, and are deeply divided into three or more narrow linear segments 1–2 mm wide.

The cream to white flowers are solitary, about 2.5 cm across, and borne on slender stalks up to 5 cm long. The flowers have 5 broad white to cream petals 12–17 mm long, are ovate-oblong, toothed or lobed with a blunt tip. Surrounded by 5 narrow green sepals (8–20 mm long).  Stamens mostly 15

The fruits are rounded but flattened capsules, 8–12 mm across and 7–12 mm long, are 3-celled, opening at apex, and contains 45-60 seeds brown to black, thin pyramidal-like angular seeds (Eichler 1986; Parsons & Cuthbertson 2001; Navie 2004).

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

Flower colour

White, Cream

Growth form (weed type/habit)

Herb

Where it currently grows? Preferred habitat

African Rue occurs in temperate, sub-tropical, semi-arid and arid areas to altitudes of up to 2500 meters (Parsons & Cuthbertson 2001). As a weed it occurs most frequently in dryer areas, growing on waste areas, roadsides, cultivated areas, and pastures. It also inhabits rangelands and grasslands (Navie 2004).

Are there similar species?

African Rue is quite distinctive and not likely to be confused with other species present in Australia (Navie 2004).

Why Is It A Weed?

What are its impacts?

African Rue is a drought resistant shrub that competes with native shrubs and grasses for moisture and nutrients affecting pasture production in the Rangelands grazing areas. It has a competitive advantage over native plants as it germinates earlier in the spring. This weed is difficult to control once established (DPIRD WA 2021). They also have an allelopathic effect, inhibiting both germination and growth of some plants (Government of South Australia 2021).

Agriculture: African Rue can be toxic due to the presence of several alkaloids occurring in all parts of the plant. However, the plant appears to be highly unpalatable to stock due to its bitter taste, and there are few actual reports of poisonings (Parsons & Cuthbertson 2001). If consumed by stock, it can cause livestock poisonings, especially during drought. Consumption by animals causes reduced fertility and abortions. It is also a known agricultural seed contaminant (DPIRD WA 2021).

Native ecosystems: Although it is a vigorously growing plant, it only occurs sporadically in small patches throughout parts of South Australia, and only occasionally in New South Wales and Victoria. Its effect on native plant communities is unknown, but it is somewhat drought and salt tolerant, and could cause considerable problems in semi-arid and arid regions (Parsons & Cuthbertson 2001).

How does it spread?

Dispersal of African Rue is mainly by seeds, the majority of which fall close to the parent plant. Seeds can be dispersed by the flow of water over the soil surface, in mud tracked by animals or vehicles, or by animals/stock which may eat the fruit (Parsons & Cuthbertson 2001). Asexual reproduction can occur by suckering from the root system, and the plant can therefore be dispersed if rootstock is moved to new areas during cultivation (Parsons & Cuthbertson 2001; Navie 2004).

What is its history in Australia?

The precise time of introduction of African Rue into Australia is not known. It was introduced into the United States in 1928, and probably later into Australia (Parsons & Cuthbertson 2001). It was recorded as naturalised in New South Wales on heavy soils at Wirruna Station in 1933 and at Savernake in 1937 (AVH 2021), but is currently most common in South Australia (Parsons & Cuthbertson 2001; Navie 2004) first collected in SA in 1943 and in Victoria in 1955 (AVH 2021).

How To Manage It?

Best practice management

A difficult to control plant once established, African Rue can be control be physical removal and herbicides, with repeated herbicide application proving most successful.

Non-chemical control: Individual plants of African Rue can be dug out and burned relatively easily, however, as regrowth can occur from any root fragments left in the soil. The roots are extensive in established plants with the root system  spreading both down and out, and can respond to light rains and deeply penetrating soil moisture with the taproot recorded to reach down 2.5 m and lateral roots to more than three metres (Government of South Australia 2021). Due to the extensive root system that regrows if left in the soil chemical control is considered to be more efficient (Parsons & Cuthbertson 2001).

Chemical control: Herbicides can be applied to the leaves prior to flowering, with repeated spraying as required until the plants are killed (Parsons & Cuthbertson 2001; DPIRD WA 2021) due to the plant's ability to regenerate from deep in the soil profile (Government of South Australia 2021). 

Government of South Australia (2021) state, that a knock-down herbicide, applied during early flowering, will control most growth above ground. If applied earlier than flowering, plants may be too small to absorb enough herbicide to kill the entire root system and many plants may still be emerging from winter senescence. If applied late in the flowering period there may not be sufficient translocation to kill the entire root system. As the herbicide has no residual properties, seedlings and roots that survived the treatment are subsequently able to emerge. Spot spraying with non-selective soil-active herbicides provides useful control of African Rue on roadsides, but damage to desirable plants will occur. Established plants that have the surface 25 mm of soil removed by road works will re-establish from their subterranean stems. In farming areas with close crop-pasture rotations weed control during cropping years is likely to limit African Rue.  

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

Does it have a biological control agent?

NO

When does it grow? (lifecycle/growth calendar)

Seeds of African Rue germinate in early spring, and germination continues sporadically throughout the summer given adequate moisture (Parsons & Cuthbertson 2001). Flowering occurs from late spring to early autumn, with a major peak in November-December, and fruits develop to maturity about one month after the flowers are fully open (Parsons & Cuthbertson 2001, Navie 2004). All above-ground growth dies back in early winter, and the plants re-shoot from the perennial root stock in August-September (Parsons & Cuthbertson 2001).

Where Is It Found?

Which states and territories is it found?

NSW, SA, VIC

What areas within states and territories is it found?

African Rue is mainly confined to south-eastern areas of South Australia, but occurs occasionally in southern New South Wales and northern Victoria (Navie 2004). In South Australia it occurs in isolated patches in the Flinders Ranges, Northern Lofty, Eastern, Murray, and South-eastern regions (Eichler 1986).

Where does it originate?

African Rue is native to Spain and from northern Africa across to Tibet (Richardson et al. 2006), and extends into areas in Pakistan, India and southern Russia and China (Parsons & Cuthbertson 2001; POWO 2021; USDA 2021).

National And State Weed Listings

Is it a Weed of National Significance (WONS)?

NO

Where is it a declared weed?

SA, 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

Peganum harmala

Other scientific names (synonyms)?

Does it have other known common name(s)?

Syrian Rue, Wild Ru, Peganum, Harmal Peganum, Harmal, Harmala