Stinking Iris (Iris foetidissima)

Present distribution

Scientific name:	Iris foetidissima L.
Common name(s):	stinking Iris

Map showing the present distribution of this weed.

Habitat:

Occurs around old homestead sites, near plantations and in forest remnants, often in appreciable quantities (Connor 1977). Open woods, hedge banks and shady places (PFAF 2009), Forest remnants (Connor 1977). “Loves moderate shade but also does well in considerable sunlight.” (Paghat 2009). Prefers moderately moist/ neutral pH soil – acidic soil (Paghat 2009), but wide soil tolerance very tolerant plant (PFAF 2009; AUSG 2009). Tolerates dryness/ drought hardiness increases with age/ Tolerates maritime conditions (Paghat 2009). Thrives in a bog garden. Root stock survives adverse conditions (PFAF 2009).

Potential distribution

Potential distribution produced from CLIMATE modelling refined by applying suitable landuse and vegetation type overlays with CMA boundaries

Map Overlays Used

Land Use:
Pasture irrigation

Ecological Vegetation Divisions
Coastal; swampy scrub; freshwater wetland (permanent); treed swampy wetland; lowland forest; foothills forest; forby forest; damp forest; riparian; wet forest; rocky outcrop shrubland; western plains woodland; semi-arid woodland; riverine woodland/forest; freshwater wetland (ephemeral); saline wetland

Colours indicate possibility of Iris foetidissima infesting these areas.

In the non-coloured areas the plant is unlikely to establish as the climate, soil or landuse is not presently suitable.

Red= Very high	Orange = Medium
Yellow = High	Green = Likely

Impact

QUESTION	COMMENTS	RATING	CONFIDENCE
Social
1. Restrict human access?	3 ft tall (Paghat 2009); leaves 30-70 cm long, few branched (Spencer 2005). 1 m wide (PFAF 2009). Forms big clumps (Paghat 2009). Slow to spread (PFAF 2009). Bulbs multiply freely, can become a suffocating weed (BDBR 2009).	M	M
2. Reduce tourism?	Crushed leaves and roots emit a strong odour (PFAF 2009). As it restricts access people may try to trample through it to get to water ways releasing the odour. Some recreational uses affected.	MH	M
3. Injurious to people?	“Rhizomes are toxic” (Paghat 2009). “Plants can cause skin irritations and allergies in some people” (PFAF 2009). Spines, burrs or toxic properties at most times of the year, or may be a major component in allergies, hayfever and/or asthma.	MH	MH
4. Damage to cultural sites?	Does not have strong roots, has rhizomes (Grieves 1994). Unlikely to cause structural damage. Moderate visual effect.	ML	MH
Abiotic
5. Impact flow?	Not reported to grow near rivers streams (PFAF 2009; Paghat 2009; Connor 1977). Little or negligible affect on water flow.	L	M
6. Impact water quality?	Not reported to grow near rivers streams (PFAF 2009; Paghat 2009; Connor 1977). No noticeable effect on dissolved 02 or light levels.	L	M
7. Increase soil erosion?	“The creeping rhizomes are thick, tufted and fibrous” (Grieve 1994). Therefore may be able to bind the soil to some degree.	M	M
8. Reduce biomass?	Can become a suffocating weed (BDBR 2009). Can occur in appreciable quantities (Connor 1977). Can become crowded (AUSG 2009) but slow to spread (PFAF 2009). Direct replacement of biomass by invader.	ML	M
9. Change fire regime?	Fire resistant (FSCC 2009). Small or negligible effect on fire risk.	L	MH
Community Habitat
10. Impact on composition (a) high value EVC	EVC = Bog garden (E); CMA = West Gippsland; Bioregion = Wilsons prom; VH CLIMATE potential. Can grow just about anywhere (TEGA 2009); Open woods, scrub, hedges (BOTN 1997); Can become a suffocating weed (BDBR 2009). Thrives in bog Garden (PFAF 2009) Major displacement of some dominant spp. within a strata layer (or some dominant spp. within different layers).	MH	MH
(b) medium value EVC	EVC = Rocky outcrop shrubland / rocky outcrop He (R); CMA = West gippsland; Bioregion = Highlands southern fall; VH CLIMATE potential. Can grow just about anywhere (TEGA 2009); Open woods, scrub hedges (BOTN 1997); Cliffs (PFAF 2009). Can become a suffocating weed (BDBR 2009). Major displacement of some dominant spp. within a strata layer (or some dominant spp. within different layers).	MH	M
(c) low value EVC	EVC = Wet forest (LC); CMA = West Gippsland; Bioregion = Highlands southern fall; VH CLIMATE potential. Open woods, shady places (PFAF 2009). Forest remnants (Connor 1977). Can become a suffocating weed (BDBR 2009). Major displacement of some dominant spp. within a strata layer (or some dominant spp. within different layers).	MH	MH
11. Impact on structure?	Ability to grow just about anywhere (TEGA 2009). Open woods, scrub and hedges (BOTN 1997). Flourish in semi-wild places (Lazarides 1997). Can become a suffocating weed (BDBR 2009). Can occur in appreciable quantities (Connor 1977). Can become crowded (AUSG 2009) but slow to spread (PFAF 2009). Minor effect on >60% of the layers or major effect on < 60% of the floral strata.	MH	M
12. Effect on threatened flora?	“Can survive dense weed competition (PFAF 2009). “This Iris has the constitution of an Ox and the ability to grow just about anywhere” (TEGA 2009). Commonly found on coastal cliffs (Paghat 2009). May affect more sensitive coastal cliff species but no specific information on this species affecting threatened flora species in Australia (pers. Obs).	M	M
Fauna
13. Effect on threatened fauna?	Toxic to grazing mammals (PFAF 2009). Caused Diarrhoea and abortion in pigs and illness in cattle (Connor 1977). No specific information on threatened fauna but the potential is there that would be affected by toxicity or habitat/ food reduction.	M	M
14. Effect on non-threatened fauna?	Weed becomes suffocating (BDBR 2009) and is toxic (Connor 1977) therefore may reduce food and/or habitat.	M	M
15. Benefits fauna?	Seeds are ignored by birds (TEGA 2009). Pollinated by bees (PFAF 2009). May cause skin irritations and is toxic to mammals (PFAF 2009). No information in literature about this species providing shelter. Provides very little support to desirable species.	H	MH
16. Injurious to fauna?	“Roots of this plant are toxic to grazing mammals” and can cause skin irritation and allergies (PFAF 2009).	H	MH
Pest Animal
17. Food source to pests?	Rarely troubled by browsing deer or rabbits (PFAF 2009). Iris needs to be kept free of aphids (AUSG 2009). Supplies food for one or more minor pest species. (eg. Blackbirds or environmental insect pests).	ML	MH
18. Provides harbour?	Can occur in appreciable quantities (Connor 1977). Can become crowded (AUSG 2009). So could provide shelter for bush rabbits but it is toxic and can cause skin irritations in humans (PFAF 2009), so may be the same for other animals too.	M	M
Agriculture
19. Impact yield?	Report of “Bloody diarrhoea in pigs, two deaths, and abortion in a sow that had eaten I. foetidissima….severe purging and high temperature in cattle that ate the roots of this species (Conner 1977)” Some death of livestock is possible. Minor impact on quantity of produce (eg < 5 % reduction).	ML	M
20. Impact quality?	Report of “Bloody diarrhoea in pigs, two deaths, and abortion in a sow that had eaten I. foetidissima….severe purging and high temperature in cattle that ate the roots of this species (Conner 1977)” Some death of livestock is possible. Can occur in appreciable quantities (Connor 1977). Very likely to cause livestock to lose condition/ reduce food supply. Major impact on quality of produce (eg 5-20%). .	MH	MH
21. Affect land value?	“Seeds readily & can become a suffocating weed (BDBR 2009). Rhizomatous (Grieve 1994). Quickly recovers from damage to leaves (Paghat 2009). Therefore could be a problematic weed but not reported to grow in crops or pastures (pers obs) so is unlikely to affect land value. Little or none.	L	MH
22. Change land use?	Not enough information. Toxic (PFAF 2009). Slow to spread (PFAF 2009). Categorised as an invasive weed (Paghat 2009), but not reported to grow in crops or pastures (pers obs) so is unlikely to change land use. Little or no change.	L	MH
23. Increase harvest costs?	Not reported to grow in crops or pastures (pers obs). But there have been reports of it being eaten by and poisoning livestock so it is probably able to establish and grow in agricultural areas. It is able to recover quickly from rhizomes after leaves are damaged (Paghat 2009). Maybe be difficult and expensive to remove therefore production costs could be increased. Minor increase in cost of harvesting – eg slightly more time or labour is required.	ML	M
24. Disease host/vector?	“Iris needs to be kept free of aphids , as they are carriers of virus infection which will cause leaf streak and reduced flowering (AUSG 2009). Provides host to minor (or common) pests, or diseases.	ML	MH

Invasive

QUESTION	COMMENTS	RATING	CONFIDENCE
Establishment
1. Germination requirements?	3 feet tall (Paghat 2009). Seeds can take a year and half to germinate (Paghat 2009). Plant in cold frame…seeds take up to 18 months to germinate (PFAF 2009). No reason found in literature as to why it takes 18 months to germinate.	M	MH
2. Establishment requirements?	“Loves moderate shade but also does well in considerable sunlight.” (Paghat 2009). Ability to grow just about anywhere (TEGA 2009). Can establish under moderate canopy litter cover.	MH	MH
3. How much disturbance is required?	Occurs around old homestead sites, near plantations and in forest remnants, often in appreciable quantities (Connor 1977). Open woods, hedge banks and shady places (PFAF 2009), Forest remnants (Connor 1977). Establishes in relatively intact or only minor disturbed natural ecosystems (eg. wetlands, riparian, riverine, grasslands, open woodlands); in vigorously growing crops or in well-established pastures.	MH	MH
Growth/Competitive
4. Life form?	Perennial herb (Lazarides et al. 1997). Propagation is by seed or division of rhizome (Lazarides et al. 1997). Leaves can be thinned and it is quick to recover in spring (Paghat 2009). Geophyte, climber or creeper.	ML	MH
5. Allelopathic properties?	Not in Rice (1984), has toxic properties (Conner 1977), but no mention in literature of allelopathy (pers. Obs)	M	L
6. Tolerates herb pressure?	Thinned….quick to recover (Paghat 2009). Rarely if ever troubled by browsing deer or rabbits (PFAF 2009). Has toxic properties – animals have been reported to have eaten it but they have become ill (Conner 1977). Favoured by heavy grazing pressure as not eaten by animals/insects and not under a biological control program in Australia/ New Zealand.	H	M
7. Normal growth rate?	“It began as two slender starts, but three years later their rhizomes had spread to form one very big broad clump (Paghat 2009). “Rather slow to spread” (PFAF 2009). Growth rate equal or less than other spp. of the same life form.	M	MH
8. Stress tolerance to frost, drought, w/logg, sal. etc?	Temperatures below zero damage the leaves…. Loves moderate shade but also does well in considerable sunlight (Paghat 2009). Prefers moderately moist/ neutral pH soil – acidic soil (Paghat 2009), but wide soil tolerance very tolerant plant (PFAF 2009; AUSG 2009). Tolerates dryness/ drought hardiness increases with age/ Tolerates maritime conditions (paghat 2009). Thrives in a bog garden (PFAF 2009). Root stock survives adverse conditions (PFAF 2009). Highly tolerant of at least two of drought, frost, fire, waterlogging, and salinity, and may be tolerant of another. Susceptible to at least one.	MH	MH
Reproduction
9. Reproductive system	Outcrosses (TEGA 2009), Self pollinates (PFAF 2009). Sexual (self and cross-pollination). Root stock survives adverse conditions (PFAF 2009). Both vegetative and sexual reproduction.	H	MH
10. Number of propagules produced?	One pod contains about 40 seeds (see photo Paghat 2009). Masses of orange seeds (AUSG 2009). “Each branched stem bears up to 5 dull purple flowers” (ENGP 1996). Few branched (Spencer 2005). Estimate 5 branches with 5 Flowers each = 25 x 40 = 1000 seeds. 50-1000	ML	M
11. Propagule longevity?	Seeds can take a year and half to germinate (Paghat 2009). Survive approximately 2 years (Strykstra et al. 2002; Bekker et al 1998). Increased by division of rhizome (Lazarides et al. 1997). Greater than 25% of seeds survive 5 years, OR vegetatively reproduces.	L	MH
12. Reproductive period?	Plant lives many years (AUSG 2009). Perennial (Lazarides et al. 1997). Life span: Long (Strykstra et al. 2002). Mature plant produces viable propagules for 3–10 years.	MH	MH
13. Time to reproductive maturity?	“two years to produce seeds” (Paghat 2009). Propagation is more swiftly done by division of the clump (Paghat 2009). Increased by division of rhizome (Lazarides et al. 1997). No info at what time vegetative division can take place.	MH	M
Dispersal
14. Number of mechanisms?	No information (Strykstra et al. 2002). Seeds ignored by birds (TEGA 2009). Rhizome is creeping (Bodkin 1986). Ornamental, spread by propagation (Paghat 2009).	ML	M
15. How far do they disperse?	Bulbs multiply freely and can become crowded (AUSG 2009). Rather slow to spread (PFAF 2009). Seeds remain attached to pods for a long time/ probably gravity dispersed, and are ignored by birds (Paghat 2009). Info on its dispersal is limited (pers. Obs). But reported to be naturalised in many places far from its native range – throughout Europe and in N. America it is categorised as an invasive weed (Paghat 2009). Very unlikely to disperse greater than 200 metres, most less than 20 metres.	L	M

References

AUSG (2009). AusGardener: Iris foetidissima. Available at http://www.ausgardener.com.au/products/Gladwin-Iris.html (verified 04/09).

BDBR (2007). Iris species database at Badbear.com. Available at http://www.badbear.com/signa/signa.pl?Iris.foetidissima (verified 04/09).

Bekker, R. M., Bakker, J. P., Grandin, U., Kalamees, Milberg, P., Poschlod, P., Thompson, K. and Willems, J. H. (1998) Seed size, shape and vertical distribution in the soil: indicators of seed longevity. Functional ecology 12, 834-842.

Bodkin, F. (1986) Encyclopedia Botanica. Angus & Robertson publishers.

BOTN (2009) Botanica: The illustrated A-Z of over 10, 000 garden plants and how to cultivate them. Random House Australia.

Connor (1977) The Poisonous Plants In New Zealand. E. C. Keating, Government Printer, Wellington, New Zealand.

ENGP (1996) A-Z Encyclopedia of Garden Plants. Christopher Brickell – editor in Chief. Covent Garden books.

FSCC (2009) Fire Safe Council . com. Available at http://www.firesafecouncilnevco.com/Publications/FSC_plant03.pdf (verified 04/09).

Grieve, M. (1994) A modern herbal. A Cresset Press Book.

Lazarides, M, Cowley, K., Hohnen, P. (1997) CSIRO handbook of Australian weeds. CSIRO publishing.

Paghat (2009) Paghat’s garden: Iris foetidissima. Available at http://www.paghat.com/stinking iris.html (verified 2/04/2009).

PFAF (2009) Plants for a future – Iris foetidissima. Available at http://www.pfaf.org/database/plants.php?Iris+foetidissima (verified 04/09).

Rice (1984)

Spencer, R. (2005) Horticultural Flora of South Eastern Australia. Vol 5. Royal Botanical Gardens Melbourne. UNSW Press.

Strykstra, R., Bekker, R. M. and van Andel, J. (2002) Dispersal and life span spectra in plant communities: a key to safe site dynamics, species co-existance and conservation. Ecography 25, 145-160.

TEGA (2009) Telegraph gardening – how to grow. Available at http://www.telegraph.co.uk/gardening/howtogrow/3293722/In-focus-Iris-foetidissima.html (verified 04/09).

Global present distribution data references

Australian National Herbarium (ANH) (2008) Australia’s Virtual Herbarium, Australian National Herbarium, Centre for Plant Diversity and Research, Available at
http://www.anbg.gov.au/avh/ (verified 24/03/2009).

Department of the Environment and Heritage (Commonwealth of Australia). (1993 – On-going) Australian Plant Name Index (APNI) http://www.cpbr.gov.au/apni/index.html (verified 24/03/2009).

Global Biodiversity Information Facility (GBIF) (2008) Global biodiversity information facility, Available at http://www.gbif.org/ (verified 24/03/2009).

Integrated Taxonomic Information System. (2009) Available at http://www.itis.gov/ (verified 24/03/2009).

Missouri Botanical Gardens (MBG) (2009) w³TROPICOS, Missouri Botanical Gardens Database, Available at http://mobot.mobot.org/W3T/Search/vast.html (viewed 24/03/2009).

United States Department of Agriculture. Agricultural Research Service, National Genetic Resources Program. Germplasm Resources Information Network - (GRIN) [Online Database]. Taxonomy Query. (2009) Available at http://www.ars-grin.gov/cgi-bin/npgs/html/taxgenform.pl (verified 24/03/2009).

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