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Fortnight lily (Dietes bicolor)

Present distribution


Scientific name:

Dietes bicolor Sweet ex Klatt.
Common name(s):

fortnight lily

This weed is not known to be naturalised in Victoria
Habitat:

Margins of perennial streams & marshy areas, in full sun or light shade (GAMA 2009). Occurring in grassland, dry bushland, moist forest margins and
mountain cliffs (Bricknell 1996). Usually in montane and coastal evergreen forests (eFloras 2009). Poor soils and dry conditions (Kirsten 2004). Salt
tolerance: poor (UNIF 2009). Will thrive where little else will grow (Pienaar et al. 2004).


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
swampy scrub; treed swampy wetland; lowland forest; foothills forest; forby forest; damp forest; riparian; wet forest; high altitude shrubland/woodland; high altitude wetland; granitic hillslopes; rocky outcrop shrubland; western plains woodland; semi-arid woodland; alluvial plains woodland; riverine woodland/forest; freshwater wetland (ephemeral).

Colours indicate possibility of Dietes bicolor infesting these areas.

In the non-coloured areas the plant is unlikely to establish as the climate, soil or landuse is not presently suitable.
maps
Red= Very highOrange = Medium
Yellow = HighGreen = Likely

Impact

QUESTION
COMMENTS
RATING
CONFIDENCE
Social
1. Restrict human access?“Sword like foliage forming large clumps….bicolor 750mm high clumps” (Pienaar 1984). Self seed into dense clumps (Macoboy 1986). High nuisance value.
MH
MH
2. Reduce tourism?It occurs in clumps along the margins of perennial streams and in marshy areas, in full sun or light shade, and grows to a height of 1.2 m GAMA (2009). Likely to block access to waterways. Some recreational uses affected.
MH
MH
3. Injurious to people?No spines, burrs, thorns, reported in literature. No effect, no prickles, no injuries.
L
M
4. Damage to cultural sites?“Sword like foliage forming large clumps….bicolor 750mm high clumps” (Pienaar 1984). Rhizomatous (PLZA 2009). Unlikely to cause structural damage. Moderate visual effect.
ML
MH
Abiotic
5. Impact flow?It occurs in clumps along the margins of perennial streams and in marshy areas, in full sun or light shade, and grows to a height of 1.2 m (GAMA 2009). “spreading fans off stiff, leathery sword shaped leaves up to 2 ft in length but only ” wide.” Evergreen, leaves radiate up and out in weeping pattern (UNIF 2009). Leaves may drrop into water and slow surface flow. Minor impact on surface flow.
ML
MH
6. Impact water quality?It occurs in clumps along the margins of perennial streams and in marshy areas, in full sun or light shade, and grows to a height of 1.2 m (GAMA 2009). .” Evergreen, leaves radiate up and out in weeping pattern (UNIF 2009). Likely to reduce light levels. Noticeable but minor effects in dissolved O2 or light levels.
ML
MH
7. Increase soil erosion?“It is an excellent subject for stabilizing steep banks” about simular species D. iridiodes (GAMA 2009). Low probability of large scale soil movement.
L
MH
8. Reduce biomass?“Sword like foliage forming large clumps….bicolor 750mm high clumps” (Pienaar 1984). Self seed into dense clumps (Macoboy 1986). Biomass likely to increase.
L
MH
9. Change fire regime?No information. Leaves evergreen, thick and leathery. Possibly low fire risk.
M
L
Community Habitat
10. Impact on composition
(a) high value EVC
EVC = Swamp Scrub (E); CMA = West Gippsland; Bioregion = Strzelecki Ranges; H CLIMATE potential. May be invasive if let flowers go to seed (LNDS 2009). One account by a person who has done extensive bushland survey work and seen D. grandiflora that he has never seen D. bicolor naturalised. (WCRC 2009) - Minor Displacement of some dominant or indicator species withing any one layer/strata/
ML
H
(b) medium value EVCEVC = Wet Sands Thicket (R); CMA = Corangamite; Bioregion = Otway Ranges; H CLIMATE potential. May be invasive if let flowers go to seed (LNDS 2009). One account by a person who has done extensive bushland survey work and seen D. grandiflora that he has never seen D. bicolor naturalised. (WCRC 2009) - Very Little displacement of any indigenous species. Sparse/scattered infestataions.
L
Q
(c) low value EVCEVC = Damp Forest (LC); CMA = Philip Island Western Port; Bioregion = Central Victorian Uplands; H CLIMATE potential. May be invasive if let flowers go to seed (LNDS 2009). One account by a person who has done extensive bushland survey work and seen D. grandiflora that he has never seen D. bicolor naturalised. (WCRC 2009) - Minor displacement of dominant or indicator species within any one layer.
ML
H
11. Impact on structure?May be invasive if let flowers go to seed (LNDS 2009). One account by a person who has done extensive bushland survey work and seen D. grandiflora that he has never seen D. bicolor naturalised. (WCRC 2009). Not known to be invasive (UNIF 2009). Partial shade (UNIF 2009). “Perform best in the light dappled shade of tall open trees, but can grow in full or nearly full sun” (ONSE 2009). May affect understory plants and tree establishment.
ML
M
12. Effect on threatened flora?No information. Not known to be invasive (UNIF 2009).
M
L
Fauna
13. Effect on threatened fauna?Pests and diseases: Trouble free (Brickell 1996). The plants seldom fall prey to serious pests and diseases. (GAMA2009). Not reported to be browsed and therefore may reduce food availability. Not enough information.
M
L
14. Effect on non-threatened fauna?Not reported to be browsed and therefore may reduce food availability. Not enough information.
M
L
15. Benefits fauna?The flowers attract numbers of insects to the garden including bees and beetles that in turn serve as food for insect-eating birds (about simular species D. grandiflora (Gama 2009).
M
M
16. Injurious to fauna?No spines, burrs, thorns, reported in literature. No effect, no prickles, no injuries.
L
M
Pest Animal
17. Food source to pests?Pests and diseases: Trouble free (Brickell 1996). The plants seldom fall prey to serious pests and diseases. (GAMA2009). Nematodes main problem, usually not affected by pests. No diseases of major concern. (UNIF 2009). Provides minimal food for pest animals.
L
MH
18. Provides harbour?“Sword like foliage forming large clumps….bicolor 750mm high clumps” (Pienaar 1984). Self seed into dense clumps (Macoboy 1986). May provide shelter to pests such as bush rabbits (WCRC 2009). Capacity to harbour rabbits or foxes at low densities or as overnight cover.
MH
ML
Agriculture
19. Impact yield?Self seed into dense clumps (Macoboy 1986). Can grow in full sun (ONSE 2009) therefore could grow in pasture and reduce pasture quality. Not enough information.
M
L
20. Impact quality?Self seed into dense clumps (Macoboy 1986). It occurs in clumps along the margins of perennial streams and in marshy areas, in full sun or light shade, and grows to a height of 1.2 m (GAMA 2009). Likely to restrict access to water for livestock and may reduce pasture quality. Minor impact on quality
ML
M
21. Affect land value?Self seed into dense clumps (Macoboy 1986). Not known to be invasive (UNIF 2009). Conflicting reports/ not enough information.
M
L
22. Change land use?Self seed into dense clumps (Macoboy 1986). not enough information.
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L
23. Increase harvest costs?Self seed into dense clumps (Macoboy 1986). If it becomes a problem removal would increase harvest cost – not enough information.
M
L
24. Disease host/vector?Pests and diseases: Trouble free (Brickell 1996). The plants seldom fall prey to serious pests and diseases. (GAMA2009). Nematodes main problem, usually not affected by pests. No diseases of major concern. (UNIF 2009). Little or no host.
L
MH


Invasive

QUESTION
COMMENTS
RATING
CONFIDENCE
Establishment
1. Germination requirements?The African Iris is very easy to grow from seed (RSS 2009). Readily self seeding” (WCRC 2009). Seed coat takes one to four years to weather away before germination takes place. Natural scarification.
M
M
2. Establishment requirements?Dietes: occurring in open grassland, dry bushland, moist forest margins, and mountain cliffs (Brickell 1996). Usually in montane and coastal evergreen forests and forest margins (eFloras 2009). ). It occurs in clumps along the margins of perennial streams and in marshy areas, in full sun or light shade, and grows to a height of 1.2 m (GAMA 2009). Easily cultivated….flourishing in full sun or light shade, in almost any soil, boggy conditions. Can establish under moderate canopy.
MH
MH
3. How much disturbance is required?Establishes in open woods (ONSE 2009).
MH
MH
Growth/Competitive
4. Life form?Perennial, rhizomatous plant. (UNIF 2009). Geophyte.
ML
MH
5. Allelopathic properties?No allelopathic properties reported.
M
L
6. Tolerates herb pressure?Resent disturbance (GAMA 2009). Therefore unlikely to have large tolerance to herbivory pressure. Consumed and recovers slowly.
ML
ML
7. Normal growth rate?They multiply rapidly and are soon ready to be split again (PLZA 2009). Fast growing (Abulk 2009). Bicolor: Growth rate slow? (UNIF 2009). Conflicting evidence. But over all literature appear to be fast growing. Moderately rapid growth that will equal competitive species of the same life form.
MH
M
8. Stress tolerance to frost, drought, w/logg, sal. etc?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). Will thrive where often little else will grow (Pienaar et al. 2004). Salt tolerance: poor (UNIF 2009). Highly tolerant of waterlogging, drought (Macoboy 1986), can tolerate some frost.
MH
MH
Reproduction
9. Reproductive systemReproduces by rhizome growth and seeds (NCUN 2009). Both vegetative and sexual reproduction.
H
H
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). Multiplies rapidly by offset formation (GAMA 2009). Not enough information but reproduces rapidly: “All species self seed into dense clumps).
M
M
11. Propagule longevity?Taking one to four or more years to weather away before germination takes place (GAMA 2009). Greater than 4 years-not enough information.
M
L
12. Reproductive period?In the 2nd or 3rd year they flower (ONSE 2009). Long lived (GAMA 2009). Likely to be at least 3 years. 3-10 years
MH
M
13. Time to reproductive maturity?In the 2nd or 3rd year they flower (ONSE 2009). No information at which time vegetatitve reproduction occurs. 25 years
ML
M
Dispersal
14. Number of mechanisms?Propagation (Brickell 1996). Although grows near streams (GAMA 2009) and may float downstream or eaten by birds (Gama 2009) so maybe bird disprsed but no information on this.
ML
ML
15. How far do they disperse?Young plantlets often develop along the flower stems, rooting when they touch the ground (GAMA 2009). Very few disperse greater than 200 metres. Although grows near streams (GAMA 2009) and may float downstream or eaten by birds (Gama 2009) so maybe bird disprsed but no information on this.
L
ML


References

Abulk (2009) Abulk Wholesale Nursery. Available at http://www.abulk.com.au/awn/Dieties.html (verified 04/2009).

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

GAMA (2009) The Gardener Magazine. South Africa. Available at http://www.thegardener.co.za/feature3_feb.html (verified 04/2009).

Kirsten, K. (2004) Flora: A Gardener’s encyclopedia. Briza Publications.

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

NCUN (2009) NC State University. Dietes spp. Available at http://www.ces.ncsu.edu/depts/hort/consumer/factsheets/bulbs-spring/DieteDi.htm (verified 04/2009).

ONSE (2009) Onaleeseeds.com. Available at http://onaleeseeds.bizhosting.com/african_iris_fortnight_lily_or_morea_iris_dietes_iridioides_seeds.html (verified 04/2009).

Pienaar, K. (1984). The South African: What Flower is that? C. Struik Publishers; Foreshore, Capetown.

PLZA (2009). Plantzafrica. Available at http://www.plantzafrica.com/plantcd/dietesgrand.htm (verified 04/2009).

RSS (2009) Rare Seed source. Available at http://rareseedsource.com/proddetail.php?prod=dietes (verified 04/2009).

UNIF (2009) University of Florida – Institute of food and Agricultural Sciences. Available at http://hort.ufl.edu/shrubs/DIEBICA.PDF (verified 04/2009).

WCRC (2009). Environweeds archive. Weeds CRC. Available at http://www.weedscrc.org.au/cropweeds/crop_weeds_d.html (verified 04/2009).


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 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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