Quick Facts

Quick facts

• Karamu (Coprosma robusta) is a native plant of New Zealand that has become an environmental weed in south-eastern Australia.
• It is a large shrub or small tree with clusters of small greenish flowers and yellow, orange or red fleshy fruits.
• Karamu spreads mainly by bird-dispersed seed.
• It can impede the growth of native plants and prevent their regeneration.
• Control of Karamu requires an integrated program utilising manual control and herbicide application, and a strategy that preferentially targets fruit-bearing plants.

What Does It Look Like?

What is it?

Karamu (Coprosma robusta) is a large shrub or small tree to 6m high. The leaves are more or less oval in shape with a pointed tip. They are mostly 5–12 cm long, 3–5 cm wide, leathery, hairless, dark green on the upper surface, paler green below and borne on branchlets in opposite pairs.

Karamu has separate male and female flowers, usually (but not always) on separate male and female plants. The small greenish flowers are borne in clusters at leaf bases.

The fruit is fleshy outside and hard inside, more or less oval in outline, 8–9mm long, 4–5mm wide and yellow, orange or red in colour (Allan 1961; Jeanes 1999; McLintock 2007).

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

Flower colour

Green

Growth form (weed type/habit)

Tree, Shrub

Where it currently grows? Preferred habitat

In south-eastern Australia, Karamu is recorded from tall open forest, moist forests and woolly tea-tree scrub (Jeanes 1999; Hosking et al. 2007; National Herbarium of Victoria 2007). In its country of origin, New Zealand, it is found in forest and shrubland, especially on alluvial soils, and is a coloniser of disturbed beaches and lowland swamps (Allan 1961; Wardle 1991).

Are there similar species?

Karamu is similar to a related weedy species in south-eastern Australia, Mirror Bush (Coprosma repens) (Muyt 2001). Mirror Bush has larger fruits (6–8mm wide) and the upper leaf surface is shiny in contrast to dull in Karamu (Jeanes 1999). When not in flower or fruit, Karamu is superficially similar to other broad-leaved shrubs or trees with leaves in opposite pairs such as Lilly-pilly (Acmena smithii) and others, and has the potential to be confused with them if it occurs in the same areas as these species currently or in future (Reid 2007, pers. obs.).

Natural hybridisation occurs freely in the genus Coprosma in New Zealand and hybrids between Karamu and five other species are known there (Allan 1961). Identification of Coprosma hybrids and the parent species involved is often difficult (Wilson 1979).

Why Is It A Weed?

What are its impacts?

Native ecosystems: Karamu is an environmental weed that can invade relatively undisturbed sites and impede the growth of native plant species and prevent their regeneration, particularly in higher rainfall areas. It is a very serious threat to native vegetation and in damp and wet sclerophyll forest communities (Carr et al. 1992; Blood 2001; Muyt 2001).

Urban environments: In New Zealand it tends to be a coloniser of disturbed sites which also points to its weed potential (Wardle 1991).

How does it spread?

The seeds of Karamu are spread by birds (Hosking et al. 2007) and possibly by foxes and possums (Muyt 2001).

What is its history in Australia?

Karamu was introduced to Australia for use in horticulture. The earliest record of its availability in cultivation in Victoria is in a nursery catalogue published in 1889 (Brookes & Barley 1992). In 1948 it was collected from private property on the slopes of Mount Wellington at Fern Tree in southern Tasmania but the collection notes do not indicate if the specimen was from a cultivated or naturalised plant. In 1968 it was collected at Red Hill South on the Mornington Peninsula, Victoria, where it was noted to be common in a patch of remnant bushland. In New South Wales, it was first recorded as naturalised in 2003 near Mount Tomah Botanic Gardens where the species was cultivated (Jeanes 1999; Hosking et al. 2007; National Herbarium of Victoria 2007).

How To Manage It?

Best practice management

Non-chemical control: Seedlings of Karamu can be hand-pulled and small plants dug out.

Chemical control: A range of herbicide treatments can be used on larger plants including cutting stems back to near ground level and painting the cut stem with a suitable herbicide (the Cut-Paint method), injection of a suitable herbicide into drill holes at the base of the plant (the Drill- Fill method) and application of a suitable herbicide to cuts near the base of the plant (the Frilling method). Seedlings, fresh regrowth and plants less than 2m can be sprayed with selective and non-selective herbicides. Larger plants can be difficult to treat with sprays and significant non-target damage may occur. Fruit-bearing plants should be targeted preferentially in control programs. Follow-up treatments will be required if plants reshoot (Muyt 2001).

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)

Karamu produces flowers in spring and summer and fruits in summer, autumn and winter (Jeanes 1999).

Where Is It Found?

Which states and territories is it found?

NSW, TAS, VIC

What areas within states and territories is it found?

Karamu is sparsely distributed in south-eastern Australia but becoming increasingly common in some locations, e.g., the Mornington Peninsula in Victoria (Walsh 2007, pers. comm.). In Victoria it is naturalised in and near the Dandenong Ranges, on the Mornington Peninsula and near Portland (Jeanes 1999). In New South Wales it is known only from around Mount Tomah Botanic Gardens at Mount Tomah in the Blue Mountains (Hosking et al. 2007). Isolated occurrences are known in southern Tasmania at New Norfolk in the Derwent Valley, Fern Tree near Hobart, and in the Gordon River Dam area. All Tasmanian populations are relatively small (Tasmanian Department of Primary Industries and Water 2007).

Where does it originate?

Karamu is native to the North and South Islands of New Zealand (Allan 1961).

National And State Weed Listings

Is it a Weed of National Significance (WONS)?

NO

Where is it a declared weed?

TAS, 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

Coprosma robusta

Other scientific names (synonyms)?

Does it have other known common name(s)?

Kakaramu