DEPARTMENT OF PRIMARY INDUSTRIES Hairy willow-herb Epilobium hirsutum Victorian Alert Weed Fact Sheet Plant biology Type of weed: Garden escape. Lifeform: Medium to large, semi-aquatic perennial herb. Description: Stems: The stems of E. hirsutum are tall and erect (up to 2 metres) with branches covered in fi ne woolly hairs which help distinguishing it from other willow-herbs (Bodkin 1990). Stems die back to underground runners over winter (WSDE 2007). Leaves: Leaves are similar in colour and shape to those of willow’s, giving rise to the common name ‘willow-herb’s’. Leaves are lance to oblong shaped, covered in hairs and join opposite along Image: Steve Smithyman Plant Image: Steve Smithyman Image: Richard the stem, growing from 60-120 mm long and 10-30 mm wide (Muenscher 1980). Botanical name: Epilobium hirsutum. Flowers: Hairy willow-herb fl owers are larger Synonyms: None. than other willow-herbs (at 30mm across) and Common name: Hairy willow-herb. pink to rosy-purple in colour. The fl owers are Alternative common names: Giant/great willow-herb, codlins bell-shaped and have four broad, notched petals. and cream, fi ddle-grass. Mature fl owers have a prominent white style, Family: Onagraceae. forming a cross pattern, extending beyond the Relevant relatives: The Epilobium genus contains more than 200 fl ower petals. Flower heads develop from the species, of which more than 30 are currently classifi ed as weedy stem and leaf joints (axils) on the plant’s upper (Randall 2001). Several native willow-herbs occur in Victoria but few branches. of these species are as invasive. Correct identifi cation is vital in controlling the right species. Fruits: Fruit are in the form of long thin capsules, approximately 50-80 mm, formed after fl owering. Mature fruit split into four from the tip to reveal fl uffy white tufts of hair, joined onto the seed which help with wind dispersal. Seeds: Seeds are oval shaped and slightly fl attened, growing to 1 mm long. The seeds are a reddish-brown colour with the white woolly hair joining at the seed’s apex. Each capsule contains an average of 260 seeds per fruit capsule with a healthy plant having over 300 fruit capsules. Seeds are ripe and ready for dispersal four to six weeks after the plant fl owers. Roots: The plant has a thick, fl eshy, creeping rhizome (underground runner) and a root system adapted to living in semi-aquatic environments (Cox 1985). Rhizomes can send out new runners, either above or bellow ground, can send up new shoots which can form roots and grow into a new plant. Weed Alert! Hairy willow-herb Epilobium hirsutum Victorian Alert Weeds Importance & impacts Impacts: Ecosystems, waterways and agriculture: What are Victorian Alert Weeds? Hairy willow-herb is quick to colonise disturbance gaps and can crowd out benefi cial species within Victorian Alert Weeds are potential weeds of the semi-aquatic habitats (WSDE 2007). Infestations of future. They may pose a serious threat to Victoria’s hairy willow-herb may have dramatic consequences, agricultural and natural assets or could affect leading to the disruption of wetland systems, altering human health. Some of these weeds are thought food chains, water cycles and wetland species to occur in small numbers in Victoria and are still composition (WSDE 2007). Dieback of the plants eradicable. Other species are yet to reach Victoria, over winter may contribute detritus and nutrients to but present a serious threat if they were to arrive. wetland systems already under threat from willow Weed Spotters help the Department of Primary tree invasions. E. hirsutum is normally confi ned Industries validate the distribution of these weeds. to wetland areas but is known to have spread into Weed Spotters are individuals trained to look for undisturbed pastures, which indicates that this weed and report high priority Weed Alert species in is a strong competitor and a high threat to Victoria’s Victoria. They are recruited from the community, environment (WSDE 2007). government or industry. Social value and health impacts: The plant has been used in Egyptian and European folk medicine for treating infl ammation and tumours (Barakat et al 1997). The leaves of hairy willow-herb have also been used in Russia to make tea, although use for the above purposes is not recommended as the plant is said to be poisonous and should be handled Why is this species a with care (PFAF 2004). Victorian Alert Weed? Health hazards: The leaves have been used for herbal and medicinal uses, but there are some Once an ornamental plant used for its showy reports of violent poisoning with epileptic-like rose-like fl owers, infestations of E. hirsutum have convulsions as a result of using the plant for these often been traced back to garden escapes. Hairy purposes (PFAF 2004; Grieve 2003). willow-herb is a prolifi c seeder that competes aggressively with surrounding plants. Plants will Importance: readily re-shoot from underground runners and can be covered in downy seeds year round. Hairy Weed legislative status: Epilobium hirsutum is willow-herb is normally limited to wet and moist not declared as a noxious weed in any Australian areas and as a result, it can dramatically impact state or territory. on the natural processes of important riverine Signifi cance of the weed in Australia: and wetland habitats. Hairy willow-herb has Hairy willow-herb has naturalised within Victoria at already escaped and naturalised in several areas several locations around Geelong and Melbourne of southern Victoria and is of particular concern and one site in West Gippsland. No other states have around Geelong where it is invading wetlands reported naturalised infestations of E. hirsutum to and riverbanks. Early detection of E. hirsutum date, however climate modelling suggests that many infestations through the Weed Spotter network of Australia’s wetlands and waterways are at risk of can help prevent the spread of this plant in invasion. Victoria and Australia. Permitted/prohibited entry into Australia: Epilobium hirsutum plants and seed are permitted entry into Australia, subject to certain conditions. For more information see the AQIS ICON import conditions database at www.daffa.gov.au/aqis/ import/icon-icd or call 1800 020 504. Victorian Weed Risk Assessment: Hairy willow- herb is considered to be a high threat because of its potential to spread quickly and dominate sensitive ecosystems. Infestations are diffi cult to eradicate because of their persistent root systems and the limited control options available for use in and around waterways. It is therefore imperative that early detection of this invasive plant takes place to help control its spread. Growth & spread Reproduction and dispersal: Hairy willow- Seed bank/propagule persistence: Hairy herb is able to reproduce both sexually, via seed willow-herb seeds are capable of remaining viable and vegetatively, via root buds. An adult plant in the ground for more than fi ve years, although is capable of producing more than 1000 seeds, the plant requires acidic soil (pH>5.5) for its seed with each having a fl uffy tuft of white hair that to germinate (WSDE 2007). Above ground parts assists with wind and water dispersal. The plant of the plant normally die back over winter, but is capable of reproducing vegetatively from root populations are very persistent as they quickly re- buds within the fi rst growing season, making shoot from rhizomes in spring. Control methods early identifi cation of the species important for often kill only above ground plant parts and improving the success of control attempts (Lenssen regeneration occurs quickly from the persistent et al 2003). root system. Rate of growth and spread: Hairy willow-herb Origin: Native to Eurasia and northern Africa. is an aggressive competitor and a fast grower, fl owering after just 10-12 weeks of growth (WSDE Where it grows: Hairy willow-herb tends to 2007). The plant can spread short distances grow exclusively in moist and fl ood prone soils quickly via rhizome and stolon shoots, and greater and is even capable of growing at altitudes as high distances via wind, water and animal dispersed as 2,500 metres (Traba et al 2004; Etherington seeds (WSDE 2007). The plant forms single-species 1983). Common habitat types for the plant include stands that can persist for many years and quickly riparian sites, river valleys, lake shores, wetlands, encroach on new territory. However, the plant’s ditches and waste areas (Polunin 1990; Muenscher spread is somewhat limited due to its intolerance 1980). Several native willow-herb species occur of environmental extremes, especially water and occasionally in Victoria, occupying similar habitats nutrients. to those of the hairy willow-herb. Growth calendar Jan Feb Mar April May June July Aug Sept Oct Nov Dec Flowering Seeding Germination Stem growth Die back Notes: Growth calendar is broadly based on behaviour and timing of plant changes, either from overseas populations, or from limited populations in Australia. Actual behaviour of plants may differ, depending on climate and geographical location. Weedy distribution in Australia and Introductory pathway to Australia: overseas: Hairy willow-herb is considered to Introduced to Australia as an ornamental, hairy be a widespread weed in the UK, Europe, Africa willow-herb emerged as a weed in this country in and the United States. Australian populations of the 1990s (WSDE 2007). As a consequence, there hairy willow-herb are currently limited to several is now great potential for the spread of the weed locations in southern Victoria and vigilant Weed from a few naturalised populations. Other potential Spotters should help in identifying its spread. sources for new introductions include contaminated agricultural supplies such as grain and fodder.