Quick Facts

Quick facts

• Originally from North Africa, Europe and Asia, White Poplar (Populus alba) is a large deciduous tree which is widely planted as an ornamental.
• In Australia it spreads by suckers which may form dense thickets.
• It is considered a threat to riparian vegetation and disturbed wetlands.
• Because of its suckering ability, White Poplar may be difficult to eradicate in problem areas.
• Can be controlled by continued application of herbicides to new suckers and foliage.

What Does It Look Like?

What is it?

White Poplar (Populus alba) is an erect, spreading or columnar, deciduous tree to 20 m tall. It has a white-grey to pale grey rough to smooth-barked trunk, with older trees developing dark furrowed bark on the lower trunk. Up the main trunk and on larger branches the bark has patterned fissures dark bark of vertical and horizontal rhombic shapes on the white-grey to pale grey bark, sometimes clustered randomly, or sometimes grouped in horizontal to vertical clusters up and round the trunk. These rhomboid shapes are smaller on thinner trunks and branches and increase in size on larger trunks towards the base. Leaves have 3 to 5 deep lobes like a maple leaf and are normally about as wide as long, or longer than wide, ranging from 3–12 cm. leaves are borne on petioles (Leaf-stalks) at least one-quarter as long as the leaf. Smaller leaves occur on shorter shoots which are 3–6 cm long, and are normally longer than wide. Leaves are dull dark green smooth and hairless above. Leaves below are white to pale grey  due to a covering of dense woolly hairs. Young shoots are covered with woolly hairs as seen on the underside of leaves. 

Its purplish 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. Male flowers are different from female flowers. Male flowers have 4 stamens. Female flowers have 2 stigmas.

The fruit consists of a two-valved, 3 mm long capsule with numerous tightly packed cotton-like seeds (Rodd 1982; Harden & Rodd 1990; Carr & Walsh 1996; VicFlora 2016).

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

Flower colour

Purple

Growth form (weed type/habit)

Tree

Where it currently grows? Preferred habitat

White Poplar has been recorded from riparian forest, disturbed wetlands and poorly drained depressions along roadsides and river banks (Harden & Rodd 1990; Carr & Walsh 1996; Hussey et al. 1997) in cool temperate areas with a mean annual rainfall is in the range 300–1000 mm 

Are there similar species?

White Poplar is closely related to and often resembles Willow (Salix) species. The 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 (less than 5 cm wide) compared to White Poplar, whose leaves are generally greater that 5 cm wide (Rodd 1982).

In Australia there are two additional Poplar species grown in cultivation. These are Lombardy Poplar (Populus nigra) and P. x canescens (a fertile hybrid derived from P. alba and P. tremula). 

The leaves of Lombardy Poplar lack the white hairs which densely cover the under surface of a White Poplar leaf and its leaves are never lobed as they frequently are in White Poplar. 

Populus x canescens is distinguished from White Poplar by its longer leaf stalks. Also the margins of P. x canescens are irregularly toothed or shallowly lobed, never deeply lobed as they frequently are in White Poplar (Carr & Walsh 1996).

White Poplar may also be mistaken for Silver Birch (Betula pendula). Silver Birch lacks the dense covering of white hairs on the under surface of the leaf blade of White Poplar (Groves et al. 2005).

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, White Poplar when planted on the boundaries of paddocks can sucker, with suckering plants invading the margins of pastures. 

Native ecosystems: White Poplar spreads by suckers and can form dense thickets. 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.  In Western Australia it has formed dense stands in disturbed wetlands from Perth to Albany. It is considered a threat to riparian vegetation in Victoria. It has spread along the Murrumbidgee River and in wet areas in rural parts of the Australian Capital Territory (Groves et al. 2005). In the United States White Poplar out-competes native species in a variety of soil types in sunny conditions (Remaley & Swearingen 2006).

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). The roots invade and block sewerage and drainage systems (Herbiguide 2021). 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?

Australian plants appear to be predominantly female and therefore do not produce fertile seed (Carr & Walsh 1996), reproducing and naturalising via suckering. Both spreading and columnar forms of White Poplar have been observed to reproduce via suckering (Harden & odd 1990; Carr & Walsh 1996), including the columnar cultivar, "Pyramidalis"(Carr 2008, pers. comm.).

What is its history in Australia?

White Poplar is frequently grown in southern Australia as an ornamental (Rodd 1982) but its exact date of introduction is not known.

How To Manage It?

Best practice management

There is limited information available on the control of White 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: In the United States hand removal of seedlings and small trees has proven successful 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)

Male and female catkins are produced on separate trees and normally start to appear in early spring, well before the leaves develop. In Australia it is presumed that the majority if not all of the plants are female (Carr & Walsh 1996), so when the fruiting capsules mature in late spring and early summer, the numerous small cottony seeds that are released are unfertilised. Therefore, in Australia reproduction in White 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, TAS, VIC, WA

What areas within states and territories is it found?

In New South Wales, White Poplar is naturalised in the Bendemeer – Tamworth region on the Northern Tablelands. It is also recorded from areas close to Sydney and from the Paddy's River crossing on the Hume Highway. 

In the Australian Capital Territory it has spread along parts of the Molonglo and Murrumbidgee Rivers and has invaded some wetlands in rural areas. 

In Queensland, White Poplar is regarded as sparingly naturalised, recorded near Drayton just west of Brisbane (Rodd 1982; Carr & Walsh 1996; Hussey et al. 1997; Australian Plant Census 2008; AVH 2008).

In South Australia it is recorded from near Kingston S.E. and on Kangaroo Island. It is also recorded from Adelaide and Adelaide Hills areas just to the east, extending to areas further north in the North Mount Lofty Ranges. 

In Tasmania it is recorded close to Hobart and from a few coastal regions in the north. 

In Victoria it is known from parts of the East Gippsland region, also near Yea in the Midlands region and near Winchelsea in the Otways.

In Western Australia it is naturalised in coastal areas between Perth and Albany. 

Where does it originate?

White Poplar is native to north Africa, central and south-eastern Europe and central Asia (Rodd 1982; Carr & Walsh 1996).

National And State Weed Listings

Is it a Weed of National Significance (WONS)?

NO

Where is it a declared weed?

ACT

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 alba

Other scientific names (synonyms)?

Does it have other known common name(s)?

Silver Leaved Poplar, Silver Poplar, Bolleana Poplar (narrow columnar form)