Delairea odorata Lem.

Title: Delairea odorata Lem.

Scientific Name:

Delairea odorata Lem.

Common Names:

Cape ivy

Image via GBIF

Distribution:

Invasiveness Assessment

ESTABLISHMENT

1. Germination requirements? Germination is reported to be rare, occurring in autumn. However vegetative propagules (pieces of stem and stolons) which is the main form of reproduction can root and grow when conditions are suitable (Blood 2001).

2. Establishment requirements? Reported to invade rainforest (Carr, Yugovic and Robinson 1992). Therefore can establish under low light conditions. Cut stems can survive months, then set root and grow when exposed to suitable conditions (Blood 2001).Therefore has some requirement for establishment.

3. How much disturbance is required? Establishes in undisturbed /minor disturbed natural ecosystems: heath land: sclerophyll forest and woodland: riparian vegetation: rainforest (Carr, Yugovic and Robinson 1992).

GROWTH / COMPETITIVE

4. Life form? Vine (Carr, Yugovic and Robinson 1992).

5. Allelopathic properties? No allelopathic properties described. However the species does contain pyrrolizidine alkaloids and xanthones, which are known to be toxic to fauna but not flora (Bossard, Randell & Hoshovsky 2000).

6. Tolerates herb pressure? Contains pyrrolizidine alkaloids and xanthones that make it unsuitable forage for most fauna and if slashed to ground level plants can regrow from rootstock (Bossard, Randell & Hoshovsky 2000). Bio-Control agents have been researched in Sth Africa and a program developed in California, however no such efforts are reported in Australia (Bossard, Randell & Hoshovsky 2000 and Balciunas & Smith 2006).

7. Normal growth rate? Reported to be a fast growing vine (Weber 2003). In California it has been reported as spreading more rapidly than any other weeds species. Average growth rates of plants around San Francisco have been calculated to one foot of growth per month. (Alvarez 1997).

8. Stress tolerance to frost, drought, w/logg, sal. etc? Tolerates some salinity (recorded on salt exposed bluffs) (Alvarez 1997). Drought tolerant (Blood 2001).
Reported in seasonal wetlands, therefore tolerant of waterlogging (Bossard, Randell & Hoshovsky 2000). Frost tender (Blood 2001), however Nelson (1999) reports that hard frosts appear to stimulate seed set, therefore while frost may damage the plant, it may not kill it. Foliage has high moisture content and therefore resistant to burning also plants can regrow from rootstock (Bossard, Randell & Hoshovsky 2000).

REPRODUCTION

9. Reproductive system? Produces seed, however primary mode of reproduction is vegetative, through stolons and stem fragments (Bossard, Randell & Hoshovsky 2000 and Muyt 2001).

10. Number of propagules produced? Large plants can produce more than 40,000 seeds annually (Muyt 2001).

11. Propagule longevity? Reproduction primarily through vegetative means .Stem fragments can persists for months before setting root under favourable conditions (Blood 2001). Seed longevity unknown. Seed doesn’t germinate readily and the seeds are tiny, 2 mm long (Muyt 2001). Therefore assume propagule longevity <5yrs

12. Reproductive period? Long lived, can form monocultures (Bossard, Randell & Hoshovsky 2000).

13. Time to reproductive maturity? Reach sexual maturity within two years (Muyt 2001).

DISPERSAL

14. Number of mechanisms? Seeds are 2 mm with hairs attached, spread by wind and water (Muyt 2001). Vegetative propagules spread by water and deliberate human actions (Alvarez 1997).

15. How far do they disperse? Wind dispersed seed can travel distances of more than 1 km.

Impact Assessment

RECREATION

1. Restrict human access? Can from dense tangled curtains of vegetation, including in riparian areas (Muyt 2001). Access would be difficult and would require significant works to control the species to maintain access due to the species rapid growth.

2. Reduce tourism? Fragrant ornamental species can alter aesthetics (Blood 2001).

3. Injurious to people? Toxic to people (Richardson, Richardson & Shepherd 2006). Toxins include pyrrolizidine alkaloids and xanthones, which are contained in the leaves and present all year (Bossard, Randell & Hoshovsky 2000). No reported fatalities.

4. Damage to cultural sites? Fragrant ornamental species could alter aesthetics (Blood 2001).

ABIOTIC

5. Impact flow? Flood mitigation strategies can be impacted upon by this species invading riparian areas (Bossard, Randell & Hoshovsky 2000).

6. Impact water quality? No reported evidence that this species impacts on water quality factors such as dissolved oxygen or temperature. However the plant is said to contain compounds that are toxic to fish and may be released into the water (Bossard, Randell & Hoshovsky 2000).

7. Increase soil erosion? Can contribute to soil erosion on hillsides (Bossard, Randell & Hoshovsky 2000).

8. Reduce biomass? The weight of the ivy can cause trees to fall, and dense canopy of the vine can smother species of the lower strata and reduce growth (Bossard, Randell & Hoshovsky 2000).

9. Change fire regime? Foliage has high moisture content (Bossard, Randell & Hoshovsky 2000).This would constitute a change in fuel properties and have some impact on fire intensity (Brooks et al 2004).

COMMUNITY HABITAT

10(a) Impact on composition of high value EVC? EVC= Riparian Forest (V); CMA= Corangamite; Bioreg= Otway Plain; VH CLIMATE potential. The weight of the ivy can cause trees to fall, the dense canopy of the vine can smother species of the lower strata and reduce growth and regeneration of species and can form monocultures (Bossard, Randell & Hoshovsky 2000).

10(b) Impact on medium value EVC? EVC= Lowland Forest (D); CMA= Corangamite; Bioreg= Otway Plain; VH CLIMATE potential. The weight of the ivy can cause trees to fall, the dense canopy of the vine can smother species of the lower strata and reduce growth and regeneration of species and can form monocultures (Bossard, Randell & Hoshovsky 2000).

10(c) Impact on low value EVC? EVC= Wet Forest (LC); CMA= Corangamite; Bioreg= Otway Plain; VH CLIMATE potential. The weight of the ivy can cause trees to fall, the dense canopy of the vine can smother species of the lower strata and reduce growth and regeneration of species and can form monocultures (Bossard, Randell & Hoshovsky 2000).

11. Impact on structure? The weight of the ivy can cause trees to fall, and the dense canopy of the vine can smother species of the lower strata and reduce growth and regeneration of species (Bossard, Randell & Hoshovsky 2000).

12. Effect on threatened flora? Can significantly reduce the species richness and diversity of an area, and render habitat in protected reserves for plant species worthless (Bossard, Randell & Hoshovsky 2000).

FAUNA

13. Effect on threatened fauna? Can render habitat in protected reserves for animal species worthless (Bossard, Randell & Hoshovsky 2000).

14. Effect on non-threatened fauna? Significant alteration of habitat; reducing plant species richness and diversity and therefore diversity of food and shelter available. Invasion by cape ivy can render habitat in protected reserves for animal species worthless (Bossard, Randell & Hoshovsky 2000).

15. Benefits fauna? Nothing reported. Insects may visit flowers, dense foliage may provide some shelter.

16. Injurious to fauna? Foliage contains compounds toxic to mammals, spiders and fish (Bossard, Randell & Hoshovsky 2000). Compounds toxic but not necessarily lethal to rats (Connor 1977).

PEST ANIMAL

17. Food source to pests? Little reported to eat the plant.

18. Provides harbor? Dense foliage could provide shelter.

AGRICULTURE

19. Impact yield? Reported to be primarily a weed of conservation areas and public amenity (Scott & Delfosse 1992).

20. Impact quality? Reported to be primarily a weed of conservation areas and public amenity (Scott & Delfosse 1992).

21. Affect land values? Reported to be primarily a weed of conservation areas and public amenity (Scott & Delfosse 1992).

22. Change land use? Reported to be primarily a weed of conservation areas and public amenity (Scott & Delfosse 1992).

23. Increase harvest costs? Reported to be primarily a weed of conservation areas and public amenity (Scott & Delfosse 1992).

24. Disease host/vector? No evidence of this reported.

Assessment ratings originally made by the Victorian Department of Primary Industries.

The entry of this assessment was made possible through the generous support of Nature's Weeding Centre.

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referenced by (1)

wra997: Common Name - C (via Cape ivy)

Article: wra8702 (permalink)
Categories: :wra:d, :wra:inv1, :wra:invh, :wra:inv2, :wra:invmh, :wra:inv3, :wra:inv4, :wra:invml, :wra:inv5, :wra:invl, :wra:inv6, :wra:inv7, :wra:inv8, :wra:inv9, :wra:inv10, :wra:inv11, :wra:inv12, :wra:inv13, :wra:inv14, :wra:inv15, :wra:imp1, :wra:impmh, :wra:imp2, :wra:impml, :wra:imp3, :wra:imp4, :wra:imp5, :wra:imp6, :wra:impl, :wra:imp7, :wra:imp8, :wra:imp9, :wra:imp10a, :wra:imph, :wra:imp10b, :wra:imp10c, :wra:imp11, :wra:imp12, :wra:imp13, :wra:imp14, :wra:imp15, :wra:imp16, :wra:imp17, :wra:imp18, :wra:impm, :wra:imp19, :wra:imp20, :wra:imp21, :wra:imp22, :wra:imp23, :wra:imp24
Date: 19 February 2023; 8:01:31 PM AEDT

Author Name: David Low
Author ID: adminDavid