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Invasiveness Assessment - English ivy (Hedera helix) in Victoria

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Plant invasiveness is determined by evaluating a plant’s biological and ecological characteristics against criteria that encompass establishment requirements, growth rate and competitive ability, methods of reproduction, and dispersal mechanisms.

Each characteristic, or criterion, is assessed against a list of intensity ratings. Depending upon information found, a rating of Low, Medium Low, Medium High or High is assigned to that criterion. Where no data is available to answer a criterion, a rating of medium (M) is applied. A description of the invasiveness criteria and intensity ratings used in this process can be viewed here.

The following table provides information on the invasiveness of English ivy.

A more detailed description of the methodology of the Victorian Weed Risk Assessment (WRA) method can be viewed below:

Victorian Weed Risk Assessment (WRA) method (PDF - 630 KB)
Victorian Weed Risk Assessment (WRA) method (DOC - 1026 KB)
To view the information PDF requires the use of a PDF reader. This can be installed for free from the Adobe website (external link).

Common Name: English ivy
Scientific name: Hedera helix

Question
Comments
Rating
Confidence
Establishment
Germination requirements?Although light may inhibit germination to some extent (Metcalfe 2005), H. helix is an opportunistic germinator.
H
H
Establishment requirements?‘Will grow in variable light conditions but prefers shade, damp soils, and a moist, cool environment’ (ISSG 2005).
MH
MH
How much disturbance is required?Occurs in ‘coastland, estuaries, natural forest, planted forests, riparian zones, urban areas, wetlands… where it infests woodlands, forest edges, fields, hedgerows, coastal areas, salt marsh edges ’ (ISSG 2005).
MH
MH
Growth/Competitive
Life form?Variable in life form – ‘it may be a perennial herbaceous vine or climber, a herb, a woody subshrub, or rarely a tree’ (Metcalfe 2005).
ML
H
Allelopathic properties?‘Known to produce chemicals that kill other plants (Allelopathy)’ (Blood 2001).
MH
MH
Tolerates herb pressure?A number of vertebrate species browse H. helix. In England, where sheep graze ivy, colonisation of grassland areas and woodland understorey may be severely restricted. A wide range of anthropods are found to feed on H. helix (Metcalfe 2005). Consumed and recovers slowly.
ML
H
Normal growth rate?Fast growing (ISSG 2005). Moderately rapid growth that will equal competitive species of same life form.
MH
MH
Stress tolerance to frost, drought, w/logg, sal. etc?Low tolerance of fire when it does burn. Not tolerant of waterlogged soils. Tolerant of seasonal drought. (Metcalfe 2005). ‘Tolerates.. frost to at least -15C. drought …salt’ (Blood 2001) Tolerant of 1 stress, susceptible to at least 2. Tolerant to at least 2, susceptible to at least 2.
ML
H
Reproduction
Reproductive systemProduces both vegetatively and by seeds (insect-pollinated) (ISSG 2005).
H
MH
Number of propagules produced?Fruits have one to a few hard, stone-like seeds (ISSG 2005) Rooting is prolific on all stems (Muyt 2001).
H
MH
Propagule longevity?‘Dormancy of cleaned seeds may last for up to 30 days; cleaning results in nearly 100% germination .. Seeds planted within the fruits may remain dormant for up to 57 days, associated with c. 40% seed mortality’ (Metcalfe 2005). Also produces vegetatively
L
H
Reproductive period?Longevity of plants in Australia is unknown but can live for 400 years in Europe (Muyt 2001).
H
MH
Time to reproductive maturity?Flowers are produced from about 10 years old (Metcalfe 2005).
L
H
Dispersal
Number of mechanisms?Dispersed by birds, foxes and possibly water (Muyt 2001).
H
MH
How far do they disperse?Dispersed by birds, foxes and possibly water (Muyt 2001). Very likely that some propagules will disperse greater than 1 km.
H
MH


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