Invasiveness Assessment - Agapanthus (Agapanthus praecox subsp. orientalis) 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 Agapanthus.

A more detailed description of the methodology of the Victorian Pest Plant Prioritisation Process can be viewed below:

Victorian Pest Plant Prioritisation Process: Methodology (PDF - 504 KB)
Victorian Pest Plant Prioritisation Process: Methodology (DOC - 1096KB
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Common Name: Agapanthus
Scientific name: Agapanthus praecox subsp. orientalis

Question	Comments	Rating	Confidence
Establishment
Germination requirements?	‘Propagate by division in late winter, or from seed in Spring or Autumn (Burnie et al 1998)’. Appears to require natural seasonal disturbances, such as warmer temperatures, for germination. It is documented to reproduce primarily by vegetative means in Victoria (Walsh & Entwisle 1994) but spreads also by seed (Blood 2001), and has been described as a ‘notorious self seeder (Robertson 2007)’.	MH	M
Establishment requirements?	Grows in full sun or under partial shade from trees (Leszczynska-Borys et al 1995). Invades dry schlerophyll forest & woodland and damp schlerophyll forest (Carr et al 1992). Able to establish under moderate canopy cover.	MH	MH
How much disturbance is required?	Not specifically documented occurring in undisturbed vegetation but does establish in natural ecosystems, e.g. heathland & heathy woodland, lowland grassland & grassy woodland, dry schlerophyll forest & woodland, damp schlerophyll forest, riparian vegetation & rock outcrop vegetation (Carr et al 1992).	MH	MH
Growth/Competitive
Life form?	Bulbous geophyte (Carr et al 1992).	ML	MH
Allelopathic properties?	No alleleopathic properties described from an extensive literature.	L	M
Tolerates herb pressure?	‘Plants seem to be immune to the predation of rabbits (PFAF 2008)’. Described as having ‘low’ palatability to goats (MLA 2007). Leaves and rhizomes poisonous. Sticky sap can cause severe ulceration in the mouth (Blood 2001). Evidence of minimal herbivory, but appears rarely consumed.	H	MH
Normal growth rate?	‘Naturalise readily soon forming large clumps (Burnie et al 1998)’, ‘Fast-growing perennial (Gardening World Online 2002)’. Spreads rapidly down drainage lines (BMCC 2008). Rapid growth rate.	H	M
Stress tolerance to frost, drought, w/logg, sal. etc?	Drought resistant (Bodkin 1986). Tolerates light frost (Notten 2004). ‘Marginally frost hardy (Burnie et al 1998). Grows on foreshores (GCB 2003) - tolerance to salt spray. Spreads rapidly down drainage lines (BMCC 2008) - some tolerance to waterlogging. A. africanus ‘Blooms profusely after veld fires (Burman & Bean 1985) and A. praecox as a bulbous geophyte with thick underground rhizomes, is assumed to also survive fire.	MH	M
Reproduction
Reproductive system	Documented as reproducing both sexually by seed and vegetatively (rhizome growth or fragments) (Blood 2001).	MH	MH
Number of propagules produced?	Seeds numerous (Walsh & Entwisle 1994). No. fruits/ umbel = 30-120 (Av. = 75); seeds/fruit =6-10 (Av. = 8) - 4 inflorescences x 75 fruits x 8 seeds = 2400 seeds/plant (Leszczynska-Borys et al 1995).	H	H
Propagule longevity?	‘It [seed] must be kept in the refrigerator or it will perish (Notten 2004). An indication that seed unlikely to survive 5 years under natural conditions.	L	M
Reproductive period?	Forms dense monocultures (ARC 2004), suggesting infestations would be self-sustaining.	H	M
Time to reproductive maturity?	‘Flowering can be expected from their third or fourth year (Notten 2004)’. The time taken for vegetative propagules to become separate individuals was not found described.	ML	M
Dispersal
Number of mechanisms?	‘Spread in dumped garden waste and contaminated soil (Blood 2001)’, ‘water and wind (Carr et al 1992)’. ‘Spreads rapidly down drainage lines…seed may wash down waterways (BMCC 2008)’.	MH	MH
How far do they disperse?	Dispersal via garden waste, contaminated soil (Blood 2001) or water (Carr et al 1992) could spread a few propagules greater than 1 km, but many to 200-1,000 m.	MH	MH

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