Title: Disa bracteata Sw.
South African weed orchid, African weed orchid, South African orchid, brown finger
1. Germination requirements? Sprouts in early spring (DNRE 2002). Requires natural seasonal conditions for germination.
2. Establishment requirements? Can grow in both shade and open ground (Muyt 2001). Can establish under a moderate canopy.
3. How much disturbance is required? Generally grows in disturbed areas and can be found in ‘woodlands, heathlands, roadsides, grazing lands’ (Muyt 2001). ‘Invades bushland and pastures’ (DNRE 2002) .Can establish in minor disturbed ecosystems.
4. Life form? Deciduous perennial terrestrial orchid with underground tubers’ (DNRE 2002). Geophyte.
5. Allelopathic properties? None reported.
6. Tolerates herb pressure? Known to be ‘consumed by sheep, cattle, horses and kangaroos’ (Dempster 2005). Capable of seed production under moderate herbivory pressure.
7. Normal growth rate? ‘Competes and excludes smaller indigenous flora including orchids, lilies and grasses ’ (Muyt 2001). Growth rate will exceed most other species of same life form.
8. Stress tolerance to frost, drought, w/logg, sal. etc? ‘.. tolerant to fire, frost and drought’ (Dempster 2005). No documented evidence of plants response to waterlogging or salinity. Score medium.
9. Reproductive system? Self-pollinated (Muyt 2001). Has tubers (DNRE 2002). Capable of sexual and vegetative reproduction.
10. Number of propagules produced? ‘..each capsule containing up to a thousand seeds’ (Muyt 2001). ‘Each plant produces tens of thousands of airborne seeds’ (DNRE 2002).
11. Propagule longevity? Seeds remain viable for seven years (Muyt 2001).
12. Reproductive period? Annual herb. Perennial plant, producing flowers in second or third year (Muyt 2001). No documented evidence that plant produces viable propagules for greater than 10 years.
13. Time to reproductive maturity? Produces flower in second or third year (Muyt 2001).
14. Number of mechanisms? Known to be both wind and water dispersed. ‘.. likely to be introduced accidentally on vehicles and machinery .. spread by seeds on clothing, shoes and camping equipment’ Seeds are ‘minute and dust-like .. may be blown many km’ (DNRE 2002).
15. How far do they disperse? Estimated that spread in South Australia has averaged 10 km per year. Seeds are ‘minute and dust-like .. may be blown many km’ (DNRE 2002).
1. Restrict human access? Grows up to 50 cm tall (DNRE 2002). Weed would not restrict human access.
2. Reduce tourism? As the plant can out compete other species and is common in grassy paddocks and previously cleared areas (DNRE 2002), it is likely that the weeds would have a minor effect on the aesthetics of the land but would not inhibit activities.
3. Injurious to people? Plant not documented to be injurious or toxic in any way.
4. Damage to cultural sites? Not known to occur at cultural sites.
5. Impact flow? Terrestrial species.
6. Impact water quality? Terrestrial species.
7. Increase soil erosion? The plant has tubers (1-3) and also fleshy side roots (DNRE 2002). Unlikely that the plant would contribute to soil erosion.
8. Reduce biomass? ‘Competes and excludes smaller indigenous flora including orchids, lilies and grasses’ (Muyt 2001). Biomass may increase.
9. Change fire regime? Tuberous plant with fleshy stems (DNRE 2002) . Although deciduous, unlikely to change the frequency or intensity of fires.
10(a) Impact on composition of high value EVC? EVC=Herb-rich Foothill Forest (V); CMA=Glenelg-Hopkins; Bioreg=Victorian Volcanic Plain; CLIMATE potential=VH.
‘Competes and excludes smaller indigenous flora including orchids, lilies and grasses’ (Muyt 2001). Major displacement of some dominant species in the lower strata.
10(b) Impact on medium value EVC? EVC=Herb-rich Foothill Forest (D); CMA=Glenelg-Hopkins; Bioreg=Victorian Volcanic Plain; CLIMATE potential=VH.
‘Competes and excludes smaller indigenous flora including orchids, lilies and grasses’ (Muyt 2001). Major displacement of some dominant species in the lower strata.
10(c) Impact on low value EVC? EVC=Lowland Forest (LC); CMA=Glenelg-Hopkins; Bioreg=Victorian Volcanic Plain; CLIMATE potential=VH.
‘Competes and excludes smaller indigenous flora including orchids, lilies and grasses’ (Muyt 2001). Major displacement of some dominant species in the lower strata.
11. Impact on structure? ‘Competes and excludes smaller indigenous flora including orchids, lilies and grasses’ (Muyt 2001). Likely to have a major effect on the lower strata.
12. Effect on threatened flora? In South Australia ‘Monadenia bracteata has already been found in the close vicinity of nationally declared rare and endangered species such as Psoralea parva (small scurf-pea) and Drosera praefolia (Tepper’s sundew) (Prescott 1997). In Victoria, D. bracteata has been found in several locations including the Victorian Volcanic Plains, where threatened flora such as basalt greenhood and tough scurf pea exist (DPI 2003).
13. Effect on threatened fauna? This species is not documented as posing an additional risk to threatened fauna.
14. Effect on non-threatened fauna? Not documented to have an effect on fauna spp.
15. Benefits fauna? Not known to benefit fauna.
16. Injurious to fauna? Not known to be injurious to fauna.
17. Food source to pests? Plant not known to be a food source to pests.
18. Provides harbor? Plant not known to provide harbour for pets species.
19. Impact yield? Not a weed of agriculture.
20. Impact quality? Not a weed of agriculture.
21. Affect land values? Weed not known to affect land value.
22. Change land use? Weed not documented to cause a change in priority of land use.
23. Increase harvest costs? Not a weed of agriculture.
24. Disease host/vector?Not a known host or vector for diseases of agriculture.
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Date: 4 February 2023; 5:56:03 PM AEDT
Author Name: David Low
Author ID: adminDavid
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