Dietes (Dietes iridioides)

Present distribution

Scientific name:	Dietes iridioides (L.) Sweet ex Klatt
Common name(s):	dietes

This weed is not known to be naturalised in Victoria

Habitat:

Dietes, (genus of 6 species), occur in open grassland, dry bushland, moist forest margins, and mountain cliffs. (Brickell 1996). “Usually in montane and coastal evergreen forests and forest margins” (Flora Zambesiaca 1993). Dietes are able to endure only very light frosts…and will tolerate sun or deep shade, poor soils and dry conditions. Dietes can be divided, but tend to resent disturbance and need care to re-establish (Kirsten 2004). Dietes will tolerate wind and frost (Pienaar 2004). “All Dietes are extraordinarily drought-resistant” (Macoboy 1986). All species prefer humus-rich, well drained soil that does not dry out too quickly (Burnie et al.1998). In Tanzaniz at 2308 m asl (Tropicos 2009). Alt 30-1828 m, also in tropical Africa (APD 2008). May be killed by sever winters (ONSE 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:
Forestry; pasture dryland; pasture irrigation

Ecological Vegetation Divisions
Coastal; heathland; grassy/heathy dry forest; lowland forest; foothills forest; forby forest; damp forest; wet forest; rainforest; high altitude shrubland/woodland; granitic hillslopes; rocky outcrop shrubland; western plains woodland; alluvial plains grassland; semiarid woodland; alluvial plains woodland; ironbark/box; chenopod shrubland; chenopod mallee; hummock-grass mallee; lowan mallee; broombush whipstick

Colours indicate possibility of Dietes iridioides 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?	“Grows to a height of 60 cm and a spread of 30-60 cm, forming dense clumps of basal leaves in a spreading fan” (Burnie et al. 1998). “Sword like foliage forming large clumps” (Pienaar 1984). Dietes are so tough they can be used as low hedges. Once established they self seed into dense clumps (Macoboy 1986). Could become a major impediment with significant works required to provide reasonable access, tracks closed or impassable.	H	ML
2. Reduce tourism?	“Grows to a height of 60 cm and a spread of 30-60 cm, forming dense clumps of basal leaves in a spreading fan” (Burnie et al. 1998). “Sword like foliage forming large clumps” (Pienaar 1984). Dietes are so tough they can be used as low hedges. Once established they self seed into dense clumps (Macoboy 1986). Some recreational uses may be affected.	MH	ML
3. Injurious to people?	Not described as having prickles, toxic properties or causing allergies (Brickell 1996; Flora Zambesiaca 1993; Kirsten 2004; Pienaar 1984; Macoboy 1986).	L	ML
4. Damage to cultural sites?	“Rhizomatous perennial” (Brickell 1996). Geophyte (African Plants Database 2008). Rhizomatous roots may cause moderate structural effect.	MH	ML
Abiotic
5. Impact flow?	Dietes, (genus of 6 species), occur in open grassland, dry bushland, moist forest margins, and mountain cliffs. (Brickell 1996). “Usually in montane and coastal evergreen forests and forest margins” (Flora Zambesiaca 1993). All species prefer humus-rich, well-drained soil that does not dry out too quickly (Burnie et al.1998). Not known to be aquatic.	L	M
6. Impact water quality?	Dietes, (genus of 6 species), occur in open grassland, dry bushland, moist forest margins, and mountain cliffs. (Brickell 1996). “Usually in montane and coastal evergreen forests and forest margins” (Flora Zambesiaca 1993). All species prefer humus-rich, well-drained soil that does not dry out too quickly (Burnie et al.1998). Not known to be aquatic.	L	M
7. Increase soil erosion?	It is an excellent subject for stabilising steep banks (GAMA 2009). Low probability of large scale soil movement; or decreases the probability of soil erosion.	L	ML
8. Reduce biomass?	Dietes “will thrive in semi-shade as well as full sun, often where little else will grow” (Pienaar 1984). Biomass may increase.	L	ML
9. Change fire regime?	Dietes “will thrive in semi-shade as well as full sun, often where little else will grow” (Pienaar 1984). Could create a minor change to either frequency or intensity of fire risk.	ML	ML
Community Habitat
10. Impact on composition (a) high value EVC	EVC = Ridged Plains Mallee (E); CMA = Mallee; Bioregion = Lowan Mallee; H CLIMATE potential. “Grows to a height of 60 cm and a spread of 30-60 cm, forming dense clumps of basal leaves in a spreading fan” (Burnie et al. 1998). “Sword like foliage forming large clumps” (Pienaar 1984). Dietes are so tough they can be used as low hedges. Once established they self seed into dense clumps (Macoboy 1986). Major displacement of some dominant spp. within a strata/layer (or some dominant spp. within different layers).	MH	H
(b) medium value EVC	EVC = Woorinen Sands Mallee (D); CMA = Mallee; Bioregion = Murray Mallee; H CLIMATE potential. “Grows to a height of 60 cm and a spread of 30-60 cm, forming dense clumps of basal leaves in a spreading fan” (Burnie et al. 1998). “Sword like foliage forming large clumps” (Pienaar 1984). Dietes are so tough they can be used as low hedges. Once established they self seed into dense clumps (Macoboy 1986). Major displacement of some dominant spp. within a strata/layer (or some dominant spp. within different layers).	MH	H
(c) low value EVC	EVC =Damp Forest (LC); CMA = East Gippsland; Bioregion = East Gippsland Uplands; H CLIMATE potential. “Grows to a height of 60 cm and a spread of 30-60 cm, forming dense clumps of basal leaves in a spreading fan” (Burnie et al. 1998). “Sword like foliage forming large clumps” (Pienaar 1984). Dietes are so tough they can be used as low hedges. Once established they self seed into dense clumps (Macoboy 1986). Major displacement of some dominant spp. within a strata/layer (or some dominant spp. within different layers).	MH	H
11. Impact on structure?	“Grows to a height of 60 cm and a spread of 30-60 cm, forming dense clumps of basal leaves in a spreading fan” (Burnie et al. 1998). “Sword like foliage forming large clumps” (Pienaar 1984). Dietes are so tough they can be used as low hedges. Once established they self seed into dense clumps (Macoboy 1986). May have a major effect on <60% of the floral strata.	MH	L
12. Effect on threatened flora?	No information was found in relation to VROT species.	MH	L
Fauna
13. Effect on threatened fauna?	No information was found in relation to threatened fauna.	MH	L
14. Effect on non-threatened fauna?	Not found.	M	L
15. Benefits fauna?	“Grows to a height of 60 cm and a spread of 30-60 cm, forming dense clumps of basal leaves in a spreading fan” (Burnie et al. 1998). “Sword like foliage forming large clumps” (Pienaar 1984). Dietes are so tough they can be used as low hedges. Once established they self seed into dense clumps (Macoboy 1986). May provide an important alternative source for harbour to desirable species.	ML	ML
16. Injurious to fauna?	Not described as having prickles, toxic properties or causing allergies (Brickell 1996; Flora Zambesiaca 1993; Kirsten 2004; Pienaar 1984; Macoboy 1986).	L	ML
Pest Animal
17. Food source to pests?	Animal susceptibility: not reported (NCUN 2009).	M	L
18. Provides harbour?	“Grows to a height of 60 cm and a spread of 30-60 cm, forming dense clumps of basal leaves in a spreading fan” (Burnie et al. 1998). “Sword like foliage forming large clumps” (Pienaar 1984). Dietes are so tough they can be used as low hedges. Once established they self seed into dense clumps (Macoboy 1986). It is an excellent subject for stabilising steep banks (GAMA 2009). May provide enough soil stability and foliage cover to provide harbour and permanent warrens for foxes and rabbits throughout the year.	H	ML
Agriculture
19. Impact yield?	Dietes can be divided, but tend to resent disturbance and need care to re-establish (Kirsten 2004). Little or negligible affect on quantity of yield as it is unlikely to establish in a agricultural environment.	L	ML
20. Impact quality?	Dietes can be divided, but tend to resent disturbance and need care to re-establish (Kirsten 2004). Little or negligible affect on quality of yield as it is unlikely to establish in a agricultural environment.	L	ML
21. Affect land value?	Dietes can be divided, but tend to resent disturbance and need care to re-establish (Kirsten 2004). Little or none as it is unlikely to establish in a agricultural environment.	L	ML
22. Change land use?	Dietes can be divided, but tend to resent disturbance and need care to re-establish (Kirsten 2004). Little or no change as it is unlikely to establish in a agricultural environment.	L	ML
23. Increase harvest costs?	Dietes can be divided, but tend to resent disturbance and need care to re-establish (Kirsten 2004). Little or none as it is unlikely to establish in a agricultural environment.	L	ML
24. Disease host/vector?	The plants seldom fall prey to serious pests and diseases (GAMA 2009). Dietes genus of 6 species, “pests and diseases, trouble free” (Brickell 1996). Little or no host.	L	ML

Invasive

QUESTION	COMMENTS	RATING	CONFIDENCE
Establishment
1. Germination requirements?	Not found.	M	L
2. Establishment requirements?	“Its preferred habitat is in semi-shade under tall, open trees” (Burnie et al. 1998). “Usually in montane and coastal evergreen forests and forest margins” (Flora Zambesiaca 1993). Can establish under moderate canopy cover	MH	M
3. How much disturbance is required?	Dietes can be divided, but tend to resent disturbance and need care to re-establish (Kirsten 2004). “Usually in montane and coastal evergreen forests and forest margins” (Flora Zambesiaca 1993). Dietes, (a genus of 6 species), occur in open grassland, dry bushland, moist forest margins, and mountain cliffs (Brickell 1996). Could possibly establish in healthy and undisturbed natural ecosystems (e.g. mallee, alpine, heathland).	H	ML
Growth/Competitive
4. Life form?	“Rhizomatous perennial” (Brickell 1996). Geophyte (African Plants Database 2008).	ML	M
5. Allelopathic properties?	Not mentioned in any information found. (Brickell 1996; Flora Zambesiaca 1993; Kirsten 2004; Pienaar 1984; Macoboy 1986).	L	L
6. Tolerates herb pressure?	Animal susceptibility: not reported (NCUN 2009).	M	L
7. Normal growth rate?	Not found.	M	L
8. Stress tolerance to frost, drought, w/logg, sal. etc?	Tough, drought-resistant plants will thrive in semi-shade as well as full sun. Dietes will tolerate both wind and frost (Pienaar 2004). Dietes are able to endure only very light frosts, in all other respects they are very tough, and will tolerate sun or deep shade, poor soils and dry conditions (Kirsten 2004). “All Dietes are extraordinarily drought-resistant” (Macoboy 1986). “All species…prefer humus-rich, well-drained soil that does not dry out too quickly” (Burnie et al. 1998). In coastal evergreen forests and forest margins” (Flora Zambesiaca 1993). May be killed by sever winters (ONSE 2009). Highly tolerant of drought, some tolerance to frost and possibly salinity. Probably not tolerant to waterlogging. Tolerant to at least two and susceptible to at least one.	ML	ML
Reproduction
9. Reproductive system	“Rhizomatous perennial” (Brickell 1996). Dietes seed themselves freely (Pienaar 1984). Reproduces by rhizomes growth and seeds (NCUN 2009). Both vegetative and sexual reproduction.	H	M
10. Number of propagules produced?	With the exception of D. bicolor, their flowers are strongly self fertile, producing copious numbers of seeds from hard, oblong capsules (GAMA 2009). ‘Copious numbers of seeds’ is assumed to be greater than 2,000 seeds for the purpose of this assessment.	H	ML
11. Propagule longevity?	“Taking one to four or more years to weather away before germination takes place” (GAMA 2009). Most seeds probably germinate within 5 years.	L	ML
12. Reproductive period?	Long lived (GAMA 2009). In the 2^nd or 3^rd year they flower (ONSE 2009). More specific information is needed to estimate number of years of reproduction.	M	L
13. Time to reproductive maturity?	In the 2^nd or 3^rd year they flower (ONSE 2009). 2-5 years to reach sexual maturity.	ML	ML
Dispersal
14. Number of mechanisms?	Not found.	M	L
15. How far do they disperse?	Not found	M	L

References

African Plants Database. (2008) Available at http://www.ville-ge.ch/musinfo/bd/cjb/africa/details.php?langue=an&id=22528 (verified 23/03/2009).

Brickell, C. (1996) A-Z Encyclopedia of Garden Plants. Covent Garden Books.

Burnie G, Forrester S, Grieg D, Guest S, Harmony M, Hobley S, Hackson G, Lavarack P, Ledgett M, McDonald R, Macoboy S, Molyneux B, Moodie D, Moore J, Newman D, North T, Pienaar K, Purdy G, Silk J, Ryan S, Schien G (1997) Botanica Random House. Milsons Point, NSW.

eFloras (2009) Flora Zambesiaca. http://apps.kew.org/efloras/ (23/03/2009).

GAMA (2009) The Gardener Magazine. South Africa. http://www.thegardener.co.za/feature3_feb.html (13/05/2009).

Macoboy, S. (1986) What Flower is that? Landowne-Rigby, Willoughby.

NCUN (2009) NC State University http://www.ces.ncsu.edu/depts/hort/consumer/factsheets/bulbs-spring/DieteDi.htm (13/05/2009).

ONSE (2009) OnaleeSeeds.COM http://onaleeseeds.bizhosting.com/african_iris_fortnight_lily_or_morea_iris_dietes_iridioides_seeds.html (13/05/2009).

Global present distribution data references

Australian Plant Name Index (APNI) http://www.cpbr.gov.au/cgi-bin/apni (26/03/2009).

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 17/02/2009).

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 07/05/2009).

Global Biodiversity Information Facility (GBIF) (2008) Global biodiversity information facility, Available at http://www.gbif.org/ (verified 17/02/2009).

Integrated Taxonomic Information System. (2009) Available at http://www.itis.gov/ (verified 07/05/2009).

Missouri Botanical Gardens (MBG) (2009) w³TROPICOS, Missouri Botanical Gardens Database, Available at http://mobot.mobot.org/W3T/Search/vast.html (viewed 17/02/2009).

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 26/03/2009).

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