Quick Facts

Quick facts

• Chinese violet (Asystasia gangetica subsp. micrantha) is an aggressive weed from Africa, which grows as a perennial herb that can grow in a mat-forming habit.
• Chine violet has great potential to spread in tropical areas.
• It easily spreads by regrowing from cuttings, such as disposed garden waste, and by the accidental transportation of seeds on shows and socks.
• Not necessarily separable from the other subspecies which is widely grown in the tropics.
• Has been confused with a native species in the past.

What Does It Look Like?

What is it?

Asystasia gangetica [as Asystasia gangetica subsp. micrantha] is a form of Chinese Violet. It is initially a shrubby spindly herb of about 1 m in height. With time it may well form mats of vegetation since all of the nodes are capable of forming roots on contact with the soil; the fall of any stems will result in new plants.

Flowers are tubular, white with purple markings on the lower inside surface.

Fruits are up to 3 cm long, initially green, but brown when ripe. These fruits split in half explosively (drying out is probably the trigger for this) and fling out the 4 seeds. The hooks which support the seeds in the fruit are visible in the opened fruit halves (CRC 2003, PIER 2006).

For further information and assistance with identification of this form of Chinese Violet (Asystasia gangetica) contact the herbarium in your state or territory. It is confusable with other Asystasia species and there is one native species on the tip of Cape York Peninsula.

Flower colour

White

Growth form (weed type/habit)

Herb, Shrub

Where it currently grows? Preferred habitat

Asystasia gangetica [as A. gangetica subsp. micrantha] has shown a tolerance to a range of subtropical and tropical climates, and could be suited to a large part of Australia's environment (CRC 2003). Most of the infestations are small and occur on vacant residential land, along fencelines and in neglected garden beds. Several larger outbreaks are present along roadsides and on crown land (CRC 2003).

In all these cases the plant is found on coastal sandy soils but it is thought to tolerate a wide range of soil types. It prefers full sun or part shade. Plants in deep shade do not thrive and become spindly, awaiting a break in the canopy. Often, plants in more exposed sites show some yellowing of the leaves, especially during winter (CRC 2003).

Are there similar species?

The taxonomy of Asystasia is urgently in need of a world-wide review. A. gangetica is a very variable species but the last revision recognised only 2 subspecies, subsp. gangetica and subsp. micrantha, which are not necessarily easily separated outside their native ranges. Furthermore there have been identifications of an Australian native species of Asystasia, A. australasica, as A. gangetica subsp. micrantha (Barker 2007, pers. comm.).

Why Is It A Weed?

What are its impacts?

Asystasia gangetica [as A. gangetica subsp. micrantha] is one of seventeen sleeper weeds identified by the Bureau of Rural Sciences (following consultation with the Australian Weeds Committee) which could have nationally significant impacts on agriculture if allowed to spread.

Agriculture: A. gangetica  is a known troublesome weed in tropical crops such as coffee, oil-palm and rubber plantations. It competes effectively for soil nutrients, reducing productivity and increasing management costs. It could also become and agricultural weed in Australia. It could potentially affect crops such as soybeans, vegetables, cut flowers and oil-tea tree (CRC 2003).

Native ecosystems: Chinese violet can smother all vegetation in the herbaceous layer (Pier 2006) reducing the availability of habitat for native plants and animals, hence reducing biodiversity (CRC 2003).

How does it spread?

Dispersal is by explosive fruits flinging the seeds some distance, but also by the ease with which it roots at any node which contacts soil. Since it forms mats of vegetation there is always the potential for fallen stems to root and spread the plant further. Agricultural, gardening, mining and roadwork activity all have the potential to spread this species, whether by seed or plant fragments. The dumping of garden waste is thought to have caused most of the outbreaks in New South Wales, although it has also spread at a great rate from garden plantings (CRC 2003).

What is its history in Australia?

A. gangetica [as A. gangetica subsp. micrantha] was first recorded as naturalised from the Anna Bay and Boat Harbour areas near Nelson Bay, just north of Newcastle in New South Wales in 1999 (CRC 2003, Barker 2007, pers. comm.). The original incursion of A. gangetica subsp. micrantha in the Port Stephens area is thought to be derived from an horticultural introduction with subsequent populations having also spread from garden plantings or resulting from the dumping of garden waste (Westaway et al. 2016).

How To Manage It?

Best practice management

As Asystasia gangetica [as A. gangetica subsp. micrantha] is not currently widespread the most efficient method of control is early detection and eradication. Small infestations can be easily eradicated if they are detected early but an ongoing commitment is needed to ensure new infestations do not establish. Management of the soil seedbank is particularly important and follow up over a number of years is the key to managing infestations (CRC 2003).

Chemical control: Some herbicides are available to treat A. gangetica [as A. gangetica subsp. micrantha] infestations. As maintaining groundcover and competitive desirable species is important, always get advice before spraying. Please see the Australian Pesticides and Veterinary Medicines Authority for chemical information http://www.apvma.gov.au.

Non-chemical control: Physical control: Hand weeding is a suitable approach for small infestations. Extreme care must be taken to ensure correct disposal of plant material. Much of the spread of A. gangetica [as A. gangetica ssp. micrantha] has been attributed to the incorrect disposal of plant parts which can contain seeds and broken stems which readily establish and form new plants, causing the infestation to spread. The best disposal methods which will kill seeds cheaply and easily are still being investigated (CRC 2003).

Slashing prior to seed set may help control A. gangetica [as A. gangetica ssp. micrantha]. However, equipment must be carefully cleaned to prevent further spread. Cultivation should also be avoided (CRC 2003).

Fire and biological control are not currently part of the control strategy for A. gangetica. However, revegetation may be helpful as competition from other vegetation can help suppress seedling germination. Planting alternative indigenous groundcovers and avoiding bare ground wherever possible can help prevent A. gangetica [as A. gangetica ssp. micrantha] taking hold (CRC 2003).

Any new outbreaks should be reported immediately to your state or territory weed management agency or local council. Do not try to control A. gangetica [as A. gangetica ssp. micrantha] without their expert assistance.

Does it have a biological control agent?

NO

When does it grow? (lifecycle/growth calendar)

A. gangetica [as A. gangetica subsp. micrantha] can flower and fruit year round. In the Port Stephens area in New South Wales, it grows rapidly following germination and throughout flowering and seed capsule production. In the final stage of its life cycle, the plant dies back to ground level after most of the ripe capsules have released their seeds. Winter frosts kill the above-ground plant parts but plants regrow the following spring from basal shoots.

In tropical climates plant growth is probably continuous, especially in moist conditions or following rainfall (CRC 2003).

Where Is It Found?

Which states and territories is it found?

NSW, NT, QLD

What areas within states and territories is it found?

Asystasia gangetica subsp. micrantha was first encountered in Australia in the Port Stephens area in 1999 (on the New South Wales mid-north coast) where it is established at a number of locations in and near Anna Bay and Boat Harbour (Westaway et al. 2016).

A. gangetica subsp. micrantha was later found at Shoal Water Bay Training area, north of Rockhampton in Queensland in 2011 where there are at least two naturalised populations established on this military land (HERBRECS). It is also established on the Gold Coast in south east Queensland by 2013 where it has ingressed into native vegetation in Currumbin Conservation Park (Westaway et al. 2016).

Asystasia gangetica subsp. micrantha was found naturalised near the Darwin airport in April 2015. It was present on Darwin International Airport land adjacent to the drainrunning north to Rapid Creek from behind the Rydges Darwin Airport Resort barbecue area (12.4041°S, 130°.8807’E) (Westaway et al. 2016).. 

Where does it originate?

In a paper on variation within the species A. gangetica, Ensermu (1994) recognised two subspecies, one the large-flowered type of the species from India, through-out Asia to Indonesia and Pacific Islands and the other a smaller-flowered African taxon, subsp. micrantha. Based on his work most Australian material would agree more closely with A. gangetica subsp. gangetica in having flowers more than 25 mm long. However material collected in New South Wales represents the more aggressive form of this species, subsp. micrantha, which has a flower length of less than 25 mm, although flower size is not always reliable in Australian material (Barker 2007, pers. comm.).

National And State Weed Listings

Is it a Weed of National Significance (WONS)?

NO

Where is it a declared weed?

NSW, WA

Government weed strategies and lists – Weeds Australia

Is it on the National Alert List for Environmental Weeds?

YES

Government weed strategies and lists – Weeds Australia

Is it on the Agricultural Sleeper List?

YES

Government weed strategies and lists – Weeds Australia

Names And Taxonomy

Main scientific name

Asystasia gangetica

Other scientific names (synonyms)?

• Asystasia coromandeliana Nees
• Asystasia coromandeliana var. micrantha Nees
• Asystasia gangetica (L.) T.Anderson subsp. gangetica
• Asystasia gangetica subsp. micrantha (Nees) Ensermu
• Justicia gangetica L.

Does it have other known common name(s)?

Philippine Violet