Willow herb

Epilobium billardierianum Ser. ssp. billardierianum

Smooth Willow herb is a native.

Epilobium billardierianum ssp. cinereum (A.Rich.) Raven

Variable Willow herb is a native.

Epilobium ciliatum Rafn

Glandular Willow Herb is introduced.

Epilobium hirtigerum A.Cunn.

Hairy willow herb. is a native.

Synonyms - Epilobium cinereum, Epilobium junceum.

Epilobium tetragonum L.

Square-stalked Willowherb is introduced.

Family: - Onagraceae


Willow herb

Other Names:


Glandular Willow Herb

Hoary Willow Herb.

Smooth Willow herb

Variable Willow herb


A pink flowered, four petalled, perennial or annual, stoloniferous herb up to 1 metre tall, with long, slender pods and oval toothed leaves that are alternate near the top and opposite near the base. The native species have pods that are less than 5 cm long and the introduced species have pods that are more than 6 cm long.


Various authors split sub species in various ways. Refer to botanic texts in references for more detailed information.


Two. Diamond to club shaped. Tip round. Base tapered. Hairless. Petiole as long as or shorter than blade.

First leaves:

Opposite in pairs, oval or egg shaped, wider near the base. Prominent veins. Tip round. Edges toothed and often undulating. Base tapering. Hairless. Red stem. Short or no petiole.


Opposite near base, usually alternate near top. Bluish green.

Stipules - Short leafy shoots in the axils of most leaves.

Petiole - Short to none.

Blade - Oval to parallel sided. 8-60mm long x 3-12 mm wide (E. ciliatum has broader leaves). Edges toothed except near base. Young leaves usually hairy but may be almost hairless when mature with some hairs on veins and edges. Young leaves have tips narrowing and tapering to a short sharp flexible point. 3-5 veins on each side of midrib.


150 - 1200 mm tall. Branched. Short hairs. Erect or ascendant. Stiff. Often woody near base. E. ciliatum is almost hairless and E. hirtigerum is very hairy.

Flower head:

Erect, branched, arising from the leaf axils. Often very hairy.


Pink to purple or white on stalks. Erect. In axils near top. Varying size and smaller on late season secondary shoots. There are two forms of differing sizes. Up to 10 mm diameter in Hairy Willow Herb

Ovary - 10-27 mm long. Dense short hairs. Stipe 6-20 mm long. Style is white and 1-9 mm long. Stigma is white.

Sepals - 2-4 mm long by 0.75-1.25 mm wide or 6-8 mm long. Keeled. Hairy, with glandular and non glandular hairs.

Petals - 4 Pink or white notched petals, 3.5-13.5 mm x 2-7 mm wide, merging into a slender tube 0.5-1.5 mm long with a ring of hairs inside.

Stamens - Filaments are white and of two lengths 1.5-5mm or 0.75-4.5 mm long. Anthers on longer filaments release pollen first.


Cylindrical capsule 70-90mm long. Opens in 4 lengthwise curling strips.


Brown. 0.75-1 mm long. Egg shaped. Fine long hairs. Tip flattish. Edges smooth. Base round to pointed. Surface dull, grooved and striped.


Creeping rhizome in some species.

Key Characters:

16-40 teeth on each side of the leaf, leaves oval, 6-18 mm wide = ssp. billardierianum.

1-8 teeth on each side of the leaf, leaves narrowly elliptic, 1.5-7 mm wide = ssp. cinereum.


Life cycle:

Perennial or annual herb. Seeds germinate from autumn to spring. Plants grow over the cooler months and flower from spring to summer.



Flowering times:

November to March. Ssp billardierianum tends to flower slightly later than ssp. cinereum.

Seed Biology and Germination:

Vegetative Propagules:



Population Dynamics and Dispersal:

The seed is spread by wind.

It is a common contaminant of nursery plants.

Origin and History:

Australia for Smooth Willow herb.

Australia, New Zealand and Lord Howe Island for Variable Willow herb.

North and South America for Glandular Willow Herb

Temperate South America, New Zealand and Indonesia for Hairy Willow Herb.


ACT, NSW, SA, TAS, VIC, WA for Smooth Willow Herb.

ACT, NSW, SA, QLD, TAS, VIC, WA for Variable Willow Herb, Glandular Willow Herb and Hairy Willow Herb.


Mainly in damp areas.




Plant Associations:






Weed of roadsides, cropping, gardens, glasshouse, moist sites and drains.

Tolerant to some common herbicides.


Not recorded as toxic.



Management and Control:


Eradication strategies:

Herbicide resistance:

Biological Control:

Related plants:

Hairy Willow herb (E. hirtigerum)

Showy Willow herb (E. pallidiflorum).

(E. ciliatum)

Plants of similar appearance:


Auld, B.A. and Medd R.W. (1992). Weeds. An illustrated botanical guide to the weeds of Australia. (Inkata Press, Melbourne). P192. Photo.

Burbidge, N.T. and Gray, M. (1970). Flora of the Australian Capital Territory. (Australian National University Press, Canberra). P278 Diagram.

Lazarides, M. and Cowley, K. and Hohnen, P. (1997). CSIRO handbook of Australian Weeds. (CSIRO, Melbourne). #387.1,387.2, 387.3, 387.4.

Lazarides, M. and Hince, B. (1993). CSIRO handbook of economic plants of Australia. (CSIRO, Melbourne). #505.1, 505.2.

Marchant, N.G., Wheeler, J.R., Rye, B.L., Bennett, E.M., Lander, N.S. and Macfarlane, T.D. (1987). Flora of the Perth Region. (Western Australian Herbarium, Department of Agriculture, Western Australia). P430.

Moerkerk, M.R. and Barnett, A.G. (1998). More Crop Weeds. R.G. and F.J. Richardson, Melbourne. P107-108. Diagrams. Photos.


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