White Poplar

Populus alba L.

Synonyms -

Family: Salicaceae

Names:

Populus Is Latin for Poplar
Alba is Latin for white

Other Names:

Poplar.
Silver Poplar

Summary:

A greyish, fast growing, erect, strongly suckering, deciduous tree to 30 m tall with leaves that are green on top and hairy white underneath. The leaves are triangular in outline with 3 to 7 toothed lobes. There are separate male and female plants. The males have red flowers and the females have green flowers in purple catkins in autumn. The seeds have long, silky white hairs.

Description:

Cotyledons:

Two.

First leaves:

Leaves:

Alternate
Buds are white, downy and not sticky.
Stipules - probably
Petiole - 20-30 mm long, at least half as long as the blade.
Blade - Green and shiny on the upper surface, downy white underneath. Broadly triangular with 3-5 deep lobes, 30-100 mm long x 20-100 mm wide on young shoots. On adult shoots they are smaller and oval to circular and sometimes toothed. Tip pointed. Sides lobed. Base indented.

Stems:

Up to 30 m tall.
Young stems round, downy and white.
Lower branches spreading.
Grey bark that is smooth to shallowly fissured with dark furrows appearing with age.
Winter buds with several overlapping and usually sticky scales.
Sapwood diffuse porous.

Flower head:

Females have drooping, purple catkins, 20-80 mm long, elongating in fruit.
A bract with few teeth or narrow lobes encircles the flower. A cup shape gland also encircles the flower.

Flowers:

Purple to red male flowers and green female flowers on separate plants.
Female flowers
Ovary - Superior. 2 carpels.
Stigma - 2. Simple or 2 lobed.
Calyx - Cup like gland encircling the flower.
Petals - None.
Male flowers
Calyx - Cup like gland encircling the flower.
Petals - None.
Stamens - 4-many
Anthers - Red or purple, 2 celled.

Fruit:

Capsule, 3 mm long, filled with dense, white cottony hairs, splitting open in spring with a "snow shower" of hairs.

Seeds:

Many each with a tuft of silky hairs

Roots:

Suckers freely forming dense thickets.

Key Characters:

Leaves mostly densely white-woolly below and either palmately 3-5 lobed on vigorous shoots or coarsely and shallowly toothed on weak shoots, rarely glabrescent and then ovate to elliptic.
Petiole more than 20 mm long.
Winter buds with several outer scales.
Adapted from Gwen Harden, Flora on NSW.

Biology:

Life cycle:

Deciduous tree. It drops twigs and limbs throughout the year. It produces flowers or catkins in autumn. When the seed capsules open the white cottony hairs around the seed gives the appearance of a snow storm. During the summer wind in the leaves give a flickering appearance as the leaves show their white and green sides alternately.

Physiology:

The soft wood is susceptible to many diseases and storm damage.

Reproduction:

By suckers from roots.

Flowering times:

Autumn in WA.
Releases seed in October in NZ.

Seed Biology and Germination:

Probably doesn't produce seed in WA.

Vegetative Propagules:

Forms suckers.

Hybrids:

Naturalised populations in New Zealand are all from the same clone.

Allelopathy:

Population Dynamics and Dispersal:

Spreads by suckering especially if roots have been damaged. It mainly invades open, disturbed areas. Coppices readily. Prunings and branches may take root where they contact the soil (layer). The seed is spread by wind and water flows.

Origin and History:

Europe, temperate Asia, North Africa.
Introduced as an ornamental and shelter tree.

Distribution:

ACT, NSW, QLD, SA, TAS, VIC, WA.
New Zealand.

Courtesy Australia's Virtual Herbarium.

Habitats:

Climate:

Temperate.

Soil:

Prefers moist areas.

Plant Associations:

Significance:

Beneficial:

Ornamental. Windbreak. Shelter.

Detrimental:

Weed of roadsides, disturbed areas, coastal dunes, wetlands.
The suckers from the roots form dense stands to crowd out other vegetation.
The roots invade and block sewerage and drainage systems.

Toxicity:

Not recorded as toxic.

Symptoms:

Treatment:

Legislation:

None.

Management and Control:

Continual cutting of the main tree, regrowth and suckers will eventually control the tree but this usually takes many years.
Grazing usually provides control.

Thresholds:

Eradication strategies:

Cut the main trunk and all the suckers and apply neat glyphosate immediately to the cut surface. Foliage of regrowth and new suckers should be sprayed with 1 litre of glyphosate plus 50 mL Pulse® Penetrant in 20 litres of water every time they appear.

Herbicide resistance:

None reported.

Biological Control:

Related plants:

Lombardy Poplar (Populus nigra) has leaves that are not lobed

Plants of similar appearance:

Willows.

References:

Bodkin, F. (1986). Encyclopaedia Botanica. (Angus and Robertson, Australia).

Everist, S.L. (1974). Poisonous Plants of Australia. (Angus and Robertson, Sydney).

Harden, Gwen J. (1991). Flora of NSW. (Royal Botanic Gardens, Sydney). Volume 1. P449. Diagram.

Hussey, B.M.J., Keighery, G.J., Cousens, R.D., Dodd, J. and Lloyd, S.G. (1997). Western Weeds. A guide to the weeds of Western Australia. (Plant Protection Society of Western Australia, Perth, Western Australia). P212. Photo.

Lamp, C. and Collet, F. (1990). A Field Guide to Weeds in Australia. (Inkata Press, Melbourne).

Lazarides, M. and Cowley, K. and Hohnen, P. (1997). CSIRO handbook of Australian Weeds. (CSIRO, Melbourne). #811.1

Randall, J.M. and Marinelli, J. (1996) Invasive Plants. (Brooklyn Botanic Gardens Inc. Brooklyn). P39. Photo.

Roy, B., Popay, I., Champion, P., James, T. and Rahman, A. (1998). An Illustrated Guide to Common Weeds of New Zealand. (New Zealand Plant Protection Society). P243. Photo

Acknowledgments:

Collated by HerbiGuide. Phone 08 98444064 or www.herbiguide.com.au for more information.