Invasiveness Assessment - Asparagus fern (Asparagus scandens) 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 Asparagus fern.

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)
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Common Name: Asparagus fern
Scientific name: Asparagus scandens

Question	Comments	Rating	Confidence
Establishment
Germination requirements?	Germinates from March to August. Indicating that germination requires conducive environmental conditions. It follows a pattern of seasonal variation for germination to occur. (DWLBC, 2006).	MH	MH
Establishment requirements?	Seedlings were growing in a range of conditions (Timmins and Reid, 2000). Mostly shady and damp sites in woodlands but is known to also grow in areas of closed forests to dappled shade in moist areas in its native South Africa (Timmins and Reid, 2000). Found in shady areas and appears to need moisture all year round (Scott and Batchelor, 2006). Can establish under moderate cover.	MH	H
How much disturbance is required?	Invaded disturbed, secondary native forests and scrub patches near urban areas (Timmins and Reid, 2000). It also occurs in open coastal forests (Timmins and Reid, 2000). Can invade intact as well as disturbed native forests (Timmins and Reid, 2000). In Australia it establishes in heathland, woodland, riparian vegetation and dry as well as damp sclerophyll forest (Timmins and Reid, 2000). Habitat comprises of forest remnants, regenerating forests, grassy places, rock wall and hedges (Roy et al, 2004). Known to establish in relatively undisturbed heathland areas.	MH	H
Growth/Competitive
Life form?	It is a slender, scrambling or climbing perennial (Timmins and Reid, 2000).	ML	H
Allelopathic properties?	This plant has been described in high quality papers but there has been no mention of allelopathy.	L	L
Tolerates herb pressure?	Noted that birds consume and disperse fruit but has not effect on plant reproduction and growth. In a study conducted by Timmins and Reid (2000) in New Zealand herbivory was not recorded. .	H	H
Normal growth rate?	The growth rate of climbing asparagus appears to be much slower than that of other invasive vines (Timmins and Reid, 2000). A weak growing, climbing shrublet (Batten and Bokelmann, 1966). Conversely Landcare NZ (1997) states that this species is fast growing.	ML	H
Stress tolerance to frost, drought, w/logg, sal. etc?	Most coastal distribution could reflect a susceptibility to frost but might tolerate occasional frosts (Timmins and Reid, 2000). Tolerant to heavy shade, but matures and fruits in moderate shade to full light. It exhibits a wide range of moisture tolerance. Due to underground tuberous roots plants are fire, drought and shade tolerant. Tolerates salt, shade, sun, dry or moist conditions, and most soils including sand (Blood, 2001). The plant is particularly tolerant to fire and drought and in certain areas tolerant to frost but generally it is susceptible to frost and possibly waterlogging.	MH	MH
Reproduction
Reproductive system	Flowers from September to December and fruits occur in October (Timmins and Reid, 2000). Root sections do not resprout but active meristems can produce new foliage if left in ground after control (Timmins and Reid, 2000). Reproduces from seed and vegetative by the transport of tuberous roots. (NZ Plant Conservation Network, 2005). Male and female flowers on separate plants (Blood, 2001). Reproductive system is both vegetative and sexual.	H	H
Number of propagules produced?	An average of 64 fruit was found on 1 m lengths of fruiting stems (Timmins and Reid, 2000). Round berry, 8 mm diameter, green turning orange-red, Oct-Feb, with 1-2 seeds.(NZ Plant Conservation Network, 2005). These develop into orange-red berries, each containing 1 to 9 seeds (Landcare NZ, 1997). Therefore even with up to 9 seeds per fruit each 1 m fruiting stem will produce less than 1000 seeds but each flowering event will produce between 1000-2000 propagules.	MH	MH
Propagule longevity?	There is no data available on seed longevity.	M	L
Reproductive period?	There is no information available on length of reproductive period.	M	L
Time to reproductive maturity?	Several years needed to reach maturity (Blood, 2001).	ML	MH
Dispersal
Number of mechanisms?	Birds take the fruit and seed are dispersed intact (Timmins and Reid, 2000). Spread locally by roots and tubers spread by soil movement, garden dumping and human activity. (NZ plant Conservation network, 2005)	H	H
How far do they disperse?	Fruits of the closely related A. asparagoides are eaten by birds and dispersed up to 100 m (DWLBC, 2006). Fruits and seeds of A. scandens are similar in size (Roy et al, 1998). Hence assume similar dispersal distance.	ML	MH

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