Quick Facts

Quick facts

• Originally from Europe, Lombardy Poplar (Populus nigra) is an erect, narrow winter deciduous tree growing about 40 m high with green leaves turning yellow in autumn, and lowers in catkins emerging before the leaves in spring.
• It has been planted as an ornamental in southern Australia, becoming naturalised in many areas.
• It reproduces by suckering, forming dense stands.
• It has a direct impact on rare and threatened species.
• Can be controlled by continued application of herbicides to new suckers and foliage.

What Does It Look Like?

What is it?

Lombardy Poplar (Populus nigra) is an erect narrow tree to about 40 m high with grey, rough, furrowed bark and erect branches. The smooth hairless leaves are triangular to rhombic, often wider than long, 4–12 cm long by 4–12 cm wide, dark green and slightly paler below, turn a brilliant yellow in late autumn. The leaf margins have fine, regular, gland-tipped teeth and both upper and lower surfaces are usually without hairs. Its winter buds are normally very sticky.

The red flowers are borne in catkins vertically hanging spike of flowers of one sex (either male or female) and appear on small branches before the leaves develop. In Australia plants appear to be male only. The male catkins (vertically hanging flower spikes) are 3–5 cm sometimes to 7 cm  long, stamens 12–20, with crimson red anthers.

The fruiting capsule is tightly packed with fine cotton-like unfertilised seeds (Rodd 1982; Harden 1990; Carr & Walsh 1996).

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

Flower colour

Pink

Growth form (weed type/habit)

Tree

Where it currently grows? Preferred habitat

Lombardy Poplar is commonly observed along watercourses in agricultural areas and is also recorded as naturalised in undisturbed riparian vegetation (Carr & Walsh 1996).

Are there similar species?

Poplar (Populus) species are closely related to, and often resemble, Willow (Salix) species. Winter buds in Willows have a single outer scale (small, hardened leaf), while those in the Poplars have several outer scales. Also Willow leaves are normally narrower than Poplar leaves which are normally less than 5 cm wide in Willows but greater than 5 cm wide in the Poplar (Rodd 1982).

In Australia White Poplar (Populus alba) and P. x canescens (a fertile hybrid derived from P. alba and P. tremula) are grown in cultivation. The leaves of both species are densely covered in white hairs on the under surface, while Lombardy Poplar is normally hairless. Also the leaves of White Poplar are frequently deeply lobed but never deeply lobed in Lombardy Poplar (Carr & Walsh 1996).

Why Is It A Weed?

What are its impacts?

A weed of roadsides, disturbed areas, coastal dunes, wetlands. The suckers from the roots form dense stands to crowd out other vegetation

Agriculture: Not generally a weed of agriculture. However, Lombardy Poplar when planted on the boundaries of paddocks can sucker, with suckering plants invading the margins of pastures. It is commonly observed along watercourses through agricultural areas and such trees may be either naturalised or deliberately planted.

Native ecosystems: Lombardy Poplar is a weed in South Africa and has formed dense suckering stands in wetlands near Perth. It is one of 49 non-native naturalised species in the Australian flora having a direct impact on rare and threatened species (Groves et al. 2005). Dense thickets shade out native vegetation and prevent a healthy understorey, thereby decreasing habitat for reliant native animal species. Although they have been used for bank stabilisation, they can result in erosion via the redirection of water and can trap sediment and block flow in rivers. 

Human impacts: The cottony white seeds, resembling white 'fluff' that appear after flowering in around October are reported as causing respiratory irritation to some people (Thorp & Wilson 1998 -; Groves et al. 2005). Strong root systems can disrupt water pipes and crack walls if planted too close to homes can prevent access to rivers.

How does it spread?

Lombardy Poplar does not produce seed but reproduces by suckers which can form dense copses (Groves et al. 2005). It is also presumed to grow from fallen branchlets carried down steam by rivers (Carr & Walsh 1996).

What is its history in Australia?

Lombardy Poplar is frequently grown as an ornamental in many parts of Australia. It was first planted in the Australian Capital Territory in 1926 (Groves et al. 2005). Its exact date of introduction to Australia is not known.

How To Manage It?

Best practice management

There is little information available on the control of Lombardy Poplar in Australia. However, continual cutting of the main tree, regrowth and suckers will eventually control the tree but this usually takes many years.

Non-chemical control: The closely related White Poplar (Populus alba) has been successfully controlled in the United States by hand removal of seedlings and small trees provided the majority of the root system is also removed to prevent suckering. Where cutting of the stem occurs and suckers are produced, grazing usually provides some control.

Chemical control: Chemical treatment has also been successful on seedlings. Larger trees can be manually removed and treated with herbicide, although follow-up treatment may be necessary (Remaley & Swearingen 2006). Cut the main trunk of large trees and all the suckers and immediately apply neat herbicide (glyphosate is effective) to the cut surface. Foliage of regrowth and new suckers should be sprayed with herbicide and a penetrant every time they appear (Herbguide 2021).

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)

In Australia catkins normally start to appear in early spring, well before the leaves develop. The fruiting capsules mature in late spring and early summer, when they release numerous small cottony unfertilised seeds (Carr & Walsh 1996; Groves et al. 2005). However, in Australia reproduction in Lombardy Poplar is by suckering, which can occur whenever there is soil disturbance damaging roots (Groves et al. 2005).

Where Is It Found?

Which states and territories is it found?

ACT, NSW, QLD, SA, VIC, WA

What areas within states and territories is it found?

In New South Wales, Lombardy Poplar has been recorded from the Casino and Tenterfield areas in the north of the state and then further south in the Chaffey Dam region near Tamworth. It is also known from the Paddy's River crossing on the Hume Highway west of Sydney.

It has been widely planted as an ornamental tree in moist sites and beside streams in the Australian Capital Territory and has naturalised along the Murrumbidgee River.

In Victoria it has been recorded as naturalised along the upper Genoa River and is commonly observed along watercourses through agricultural areas (Carr & Walsh 1996; Groves et al. 2005; AVH 2008).

It is also commonly grown as an ornamental in South Australia and may be partly naturalised in the Southern Lofty and the Northern Lofty regions (Electronic Flora of South Australia).

In Western Australia it has been recorded from the Milyu Nature Reserve in South Perth and further south into the Armadale, the Nannup and the Northcliffe regions (Western Australian Herbarium 1998-).

In Queensland it is found around Stanthorpe and areas just to the north (AVH 2008).

Where does it originate?

The cultivar 'Italica' originated from Lombardy, Italy. Typical Populus nigra however is widespread through central and southern Europe (Carr & Walsh 1996).

National And State Weed Listings

Is it a Weed of National Significance (WONS)?

NO

Where is it a declared weed?

ACT, 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

Populus nigra

Other scientific names (synonyms)?

Populus nigra var. italica Du Roi

Does it have other known common name(s)?

Black Poplar, Italian Poplar