Carduus pycnocephalus L.

Title: Carduus pycnocephalus L.

Scientific Name:

Carduus pycnocephalus L.

Common Names:

slender thistle, shore thistle, Italian plumeless thistle

Source & more images (via ALA)

Habitat: Subhumid warm-temperate regions having winter dominant rainfall on soils of moderate to high fertility (Parsons and Cuthbertson 1992). It is a weed of improved pastures and neglected areas, establishing readily on disturbed sites in areas with annual rainfall above 500 mm (Parsons and Cuthbertson 1992). Slender thistle invades dry coastal vegetation, mallee shrubland, lowland grassland and grassy woodland, dry sclerophyll forest and woodland and rock outcrop vegetation (Carr et al. 1992).

Distribution:


Present Distribution - Australia (source: ALA)

Invasiveness Assessment

ESTABLISHMENT

1. Germination requirements? Seed germinates after autumn rains (Parsons and Cuthbertson, 2001)

2. Establishment requirments? Can establish under shading (Mar Anon & Bartolome1993).

3. How much disturbance is required? Serious environmental weed in woodlands, riparian veg., rainforest etc. (Carr et al. 1992).

GROWTH / COMPETITIVE

4. Life form? Erect annual herb → ‘Other’ (Parsons and Cuthbertson, 2001)

5. Allelopathic properties? None described.

6. Tolerates herb pressure? Not readily grazed by stock b/c of its spiny nature (Parsons and Cuthbertson, 2001).

7. Normal growth rate? More competitive than subterranean clover & ryegrass over a wide range of nutrient levels (Parsons and Cuthbertson, 2001).

8. Stress tolerance to frost, drought, w/logg, sal. etc? Tolerant of waterlogging (grows on creek banks), salinity (occurs in coastal areas), drought (K&J 1977; Clapham et al. 1952; Carr et al. 1992; Pitcher & Russo 1995).

REPRODUCTION

9. Reproductive system? Reproducing by seed (Self & cross pollination assumed). As there is much info on plant, would have probably been stated if only one or other (Parsons and Cuthbertson, 2001).

10. Number of propagules produced? According to one study approx 833 seeds produced/plant (Goeden & Ricker 1985).

11. Propagule longevity? Most seeds germinate in the autumn after they are produced but some may remain dormant for at least 10 years. Short-term innate dormancy (several weeks to months) has been established for seeds of some thistles under certain conditions, e.g./ C. pycnocephalus & C. tenuiflorus (Sindel 1991). The length of time the seeds can survive in the soil is not known but appears to be at least 8 years (Parsons 1973; Pitcher & Russo 1995; Parsons and Cuthbertson 2001).

12. Reproductive period? Form dense populations → monocultures (Bendall 1973).

13. Time to reproductive maturity? Annual (Parsons and Cuthbertson 2001).

DISPERSAL

14. Number of mechanisms? Wind dispersal, animals, birds; pasture seed, contaminated by hay & water (Parsons and Cuthbertson 1992).

15. How far do they disperse? Several birds eat the seeds. The distance that seed can be spread by wind is not known, but is at least several hundred metres (Pitcher & Russo 1995; Parsons and Cuthbertson 1992).

Impact Assessment

RECREATION

1. Restrict human access? “Erect annual herbs commonly 60 to 100 cm high. Stems single or multiple from the base, branched with spiny wings along most of the length. Leaves deeply lobed and each lobe with numerous spines.” Dense infestations of this spiny plant would be highly annoying to people and would restrict access. No restriction to vehicle access; humans clothed appropriately would be able to move through infestations.(Parsons and Cuthbertson 2001).

2. Reduce tourism? Dense infestations of this spiny plant may affect some recreational activities.

3. Injurious to people? Plants die in early summer, but spines are present for most of the year (Parsons and Cuthbertson, 2001).

4. Damage to cultural sites? Dense infestations are likely to cause a moderate negative visual effect.

ABIOTIC

5. Impact flow? Terrestrial species (Parsons and Cuthbertson 2001).

6. Impact water quality? Terrestrial species (Parsons and Cuthbertson 2001).

7. Increase soil erosion? “Seedling establish most readily on bare or disturbed sites.” As an annual it would not contribute to soil stability. Moderate probability of large scale soil movement (Parsons and Cuthbertson 2001).

8. Reduce biomass? “Weeds of improved pastures and neglected areas.” Direct replacement of biomass by invader (Parsons and Cuthbertson 2001).

9. Change fire regime? “Flower stem is produced in early spring and plants die in early summer.” A short-lived annual, it is unlikely to change the fire regime (Parsons and Cuthbertson 2001).

COMMUNITY HABITAT

10(a) Impact on composition of high value EVC? EVC=Plains grassland (E); CMA=West Gippsland; Bioreg=Gippsland Plain; VH CLIMATE potential. Most competitive on disturbed open sites. Dominates pasture species in agricultural situations. Major impact on grasses/forbs. (Parsons and Cuthbertson 2001)

10(b) Impact on medium value EVC? EVC=Grassy dry forest (D); CMA=Port Phillip; Bioreg=Central Victorian Uplands; VH CLIMATE potential. Impact as in 10(a ) above. (Parsons and Cuthbertson 2001)

10(c) Impact on low value EVC? EVC=Lowland forest (LC); CMA=East Gippsland; Bioreg=East Gippsland Lowlands; VH CLIMATE potential. Overstorey cover may limit population density. Minor displacement of grasses/forbs. (Parsons and Cuthbertson 2001)

11. Impact on structure? In the United States, “Native vegetation is threatened by this aggressive weed that tends to form dense stands.” “Dense infestations of slender thistle eliminate other pasture species.” Major effect on the lower stratum.(WSNWCB1; Parsons and Cuthbertson 2001)

12. Effect on threatened flora? None recorded.

FAUNA

13. Effect on threatened fauna? None recorded.

14. Effect on non-threatened fauna? In the United States, “Native vegetation is threatened by this aggressive weed that tends to form dense stands.” In Victoria, the species are widespread in medium to large populations. The plants are not readily grazed by stock, therefore infestations may have a serious impact on the habitat of fauna species (WSNWCB; Carr et al. 1992; Parsons and Cuthbertson 2001).

15. Benefits fauna? No known benefits to fauna species.

16. Injurious to fauna? “Slender thistle is not readily grazed by stock because of its spiny nature.” Spines may cause some injury to fauna, though this is not documented (Parsons and Cuthbertson 2001).

PEST ANIMAL

17. Food source to pests? “Several birds, notably goldfinches [Carduelis carduelis European goldfinch] eat the seeds.” Food source to minor pest species (Parsons and Cuthbertson 2001).

18. Provides harbor? Not documented to provide harbor. A short-lived annual.

AGRICULTURE

19. Impact yield? “Slender thistle is not readily grazed by stock because of its spiny nature, and its presence also discourages animals from grazing neighbouring pasture plants. Dense infestations of slender thistle eliminate other pasture species.” Likely to reduce carrying capacity and thus have a major impact on quantity. Not known as a weed of cropping in Victoria, however, “in Tasmania it is also an important competitor with annual crops" (Parsons and Cuthbertson 2001).

20. Impact quality? Not known as a weed of cropping in Victoria, or to affect the quality of produce or harvest.

21. Affect land values? Impact on agricultural yields may reduce land value, but Carduus pycnocephalus and C. tenuiflorus, like Cirsium vulgare, are widespread throughout southern Australia, and C. vulgare is, “accepted as a permanent part of the vegetation (Parsons and Cuthbertson 2001).

22. Change land use? “…if stock is excluded from weed patches through autumn and winter, the rosette leaves become erect with softened spines, and stock eat these plants in late winter and spring, often in preference to other species.” Using this deferred method of grazing may improve land availability. (Parsons and Cuthbertson 2001).

23. Increase harvest costs? Not known to affect harvest costs.

24. Disease host/vector? Not evident.

Feedback

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

The entry of this assessment was made possible through the generous support of The Weed's Network.

Attachments:

shore_thistle_stem.jpg
shore_thistle_flower_detail.jpg
shore_thistle_flowers.jpg
shore_thistle_plant.jpg
Capture.JPG

referenced by (2)

wra3426: slender thistle/shore thistle wra1004: Common Name - I (via Italian plumeless thistle)

Article: wra2781 (permalink)
Categories: :wra:c, :wra:inv1, :wra:invmh, :wra:inv2, :wra:inv3, :wra:inv4, :wra:invl, :wra:inv5, :wra:inv6, :wra:inv7, :wra:inv8, :wra:inv9, :wra:invml, :wra:inv10, :wra:inv11, :wra:inv12, :wra:invh, :wra:inv13, :wra:inv14, :wra:inv15, :wra:imp1, :wra:impml, :wra:imp2, :wra:imp3, :wra:impmh, :wra:imp4, :wra:imp5, :wra:impl, :wra:imp6, :wra:imp7, :wra:imp8, :wra:imp9, :wra:imp10a, :wra:imp10b, :wra:imp10c, :wra:imp11, :wra:imp12, :wra:impm, :wra:imp13, :wra:imp14, :wra:imp15, :wra:imph, :wra:imp16, :wra:imp17, :wra:imp18, :wra:imp19, :wra:imp20, :wra:imp21, :wra:imp22, :wra:imp23, :wra:imp24
Date: 26 October 2009; 2:53:44 PM AEDT

Author Name: Fariba Moslih
Author ID: moslih