Quick Facts

Quick facts

• Harrisia Cactus (Harrisia martinii) is a spiny, rope-like succulent that forms dense, impenetrable mats, occurring mainly in semi-arid areas of Queensland.
• It can spread by seeds, stem fragments and root fragments.
• The dense mats formed by Harrisia Cactus are impenetrable to stock, choke out pasture species, and reduce overall land utility.
• It can be controlled by manual removal or by herbicides.

What Does It Look Like?

What is it?

shallow fibrous roots radiating from the base of the plant, and large fleshy storage roots which grow to depths of 30–50 cm.

The stems can be several meters long, bright green and fleshy, 2.5–4 cm in diameter and jointed at 30-35 cm intervals. The stems are weakly 4 or 5 ridged lengthwise, and each rib has several low tubercles (small wart-like outgrowth) 5–7.5 cm apart that are topped with rounded small depressions of grey felty hairs and spines (areoles). Each areole consists of 1–4 central spines 10–35 mm long, and 5–7 appressed radial spines 1–6 mm long. All spines become black tipped with age.

The flowers are 15–18 cm in diameter, 15–20 cm long, with white 'petals' (petaloid lobes) which may turn pink with age, merge downward into a slender green tube. The flowers are nocturnal but often remain opened the following morning before collapsing.

The fruit are bright red when mature, somewhat rounded, 2–6 cm in diameter, with a several small tubercles from which groups of 3–5 spines are produced. The fruit contains a white pulp with 400–1000 black seeds, 2–2.5 mm long (Telford 1984; Navie 2004; Parsons & Cuthbertson 2001).

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

Flower colour

White, sometimes tinged Pink

Growth form (weed type/habit)

Succulent

Where it currently grows? Preferred habitat

Harrisia Cactus is most common in semi-arid areas of Queensland, but occasionally occur in dryer sub-tropical and tropical areas. It primarily inhabits open areas such as open woodland, scrubland or pastures (Navie 2004). It is most prolific on the deep and fertile cracking clays of the brigalow (Acacia harpophylla) forests and false sandalwood (Eremophila mitchellii) scrubs of central and south-eastern Queensland. It is shade tolerant, and most large infestations occur in areas with an annual rainfall of at least 500 mm (Parsons & Cuthbertson 2001).

Are there similar species?

Three Harrisia species occur in Australia (H. martinii, H. tortuosa, H. regelii) [as Eriocereus martinii, E. tortuosus and E. bonplandii], and are all referred to as Harrisia Cactus. These species are difficult to distinguish in the field, and a number of collections of H. martinii may be misidentified (Parsons & Cuthbertson 2001; Navie 2004).

Harrisia tortuosa [as Eriocereus tortuosus] has 6–8 continuous stem ridges with only slight humps, and radial spines mostly more than 1 cm long; H. martinii has 4–5 often discontinuous stem ridges with prominent humps, and radial spines usually less than 1 cm (Telford 1984).

Harrisia regelii [as Eriocereus bonplandii] has stem ridges with only slight humps and its fruit have no spines, compared to the prominent stem-ridge humps and spiny fruit of H. martinii [as E. martinii] (Navie 2004).

Why Is It A Weed?

What are its impacts?

Agriculture: Harrisia Cactus is a prolific seeder, spreads quickly, and has the ability to eventually take over large areas of grazing country (Tanner 2007). It forms dense, tangled mats commonly to 0.6 m high. The mats are impenetrable to stock and can cover to as much as 80–90% of land area, reducing the land available for grazing significantly, interfering with mustering operations, choking out other pasture species, as well as reducing overall land utility (Parsons & Cuthbertson 2001; Paskins 2001; Land Protection 2007).

Native ecosystems: It competes strongly for light, water and ground surface with shrub species, particularly grasses, in brigalow forests; however, it is not highly tolerant of full sunlight and can be at a competitive disadvantage in open habitats, where its stems and tuberous roots grow slowly (Parsons & Cuthbertson 2001).

How does it spread?

Initially widely dispersed by human due to its use as an ornamental plant and because of its edible fruit, Harrisia Cactus is now spread unintentionally as a result of dumped garden waste, and through seed dispersal by birds, pigs and cattle. Birds are considered to be particularly important in its dispersal, as many new colonies are found in bushland where birds have perched. The cactus can then spread vegetatively from these initial colonies, either by direct growth of the stems of the pioneering plants, or by the spread of small stem fragments, which can take root when in contact with the soil. The tuberous roots of this species are able to produce new stems, and can be dug out and spread to new areas by wild pigs (Parsons & Cuthbertson 2001).

What is its history in Australia?

Harrisia Cactus is believed to have been introduced into Queensland between 1885 and 1890 as an ornamental plant. It was initially introduced into areas near Collinsville, but later outbreaks further south in Queensland are thought to have originated from these original plantings (Parsons & Cuthbertson 2001).

How To Manage It?

Best practice management

Non-chemical control: The whole plant including the roots can be dug out manually and burned. Care must be taken to ensure the removal of all tuberous roots and stem fragments, which can resprout when in contact with the soil (Land Protection 2007).

Chemical control: Early herbicide spray trials were ineffective as the amount of chemical absorbed into the stems is minimal, however, some chemical treatments have been found to be useful in conjunction with ploughing. Recent research has found that some herbicides that are absorbed through the roots from treated soil may be effective. Harrisia Cactus is best treated by spot spraying after the stems have been severed. The stems should be burned, or crushed and treated with herbicide, as fragments readily resprout if in contact with the soil (Parsons & Cuthbertson 2001).

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

Biological control: Two introduced insect species have established in the field and are useful for the control of Harrisia Cactus. A stem-boring beetle (Alcidion cericola) attacks older woody stems, and has contributed to the degradation of larger stands in the Collinsville area. A mealy bug (Hypogeococcus festerianus) has been more successful in controlling Harrisia Cactus populations by feeding on the tips of stems and buds. This limits plant grows and results in stem distortion, eventually causing the death of the plant due to excessive energy demands for new growth (Land Protection 2007).

Does it have a biological control agent?

YES

When does it grow? (lifecycle/growth calendar)

The seeds of Harrisia Cactus are highly viable and germinate readily after the first heavy rains of early summer. The seedlings are slow to develop and fragile, and are easily damaged or killed by drought stress, grazing or trampling, or other physical disturbance. Plants can reach a stem length of up to 10–15 cm by the end of the first summer, at which time the tuberous, nutrient storing, roots are developed. Stem growth slows or ceases during the colder months and recommences during in August or September after rains, and continues to the following winter. After 3–5 years the stems can reach approximately 60–90 cm, after which flowering can commence. Flowering commences between November and January, and continues until March or April (Parsons & Cuthbertson 2001).

Where Is It Found?

Which states and territories is it found?

NSW, QLD, WA

What areas within states and territories is it found?

Harrisia Cactus is commonly found in sub-coastal and semi-arid areas of central Queensland, and is relatively common, but scattered, in the south-east of this state. It is recorded from a small number of localities in New South Wales (Sydney and West Wyalong) and Western Australia (northern pastoral districts). Two other Harrisia species referred to as Harrisia martinii have been recorded from both Queensland and New South Wales (Harrisia tortuosa) [as Eriocereus tortuosus], and Queensland exclusively (Harrisia regelii) [as E. bonplandii] (Navie 2004). It has potential to spread to the Northern Territory, in areas with similar conditions to infested areas in Queensland (Paskins 2001).

Where does it originate?

Harrisia Cactus is native to South America, mainly Argentina and Paraguay (Parsons & Cuthbertson 2001).

National And State Weed Listings

Is it a Weed of National Significance (WONS)?

NO

Where is it a declared weed?

NSW, NT, QLD, 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

Harrisia martinii

Other scientific names (synonyms)?

• Cereus martinii Labour.
• Eriocereus martinii (Labour.) Riccob.

Does it have other known common name(s)?

Moonlight Cactus, Moon Cactus, Snake Cactus