Title: Tribulus terrestris L.

Scientific Name:

Tribulus terrestris L.

Common Names:

caltrop, bindi, dubblegee, puncture vine



Tribulus terrestris (puncture vine)


Source & more images (via ALA)

Habitat: Warm-temperate regions mainly on light-textured soils (Parsons and Cuthbertson, 1992). It has become a weed of cultivated crops, orchards, overgrazed pastures, stock yards, roadsides and neglected areas particularly in districts with high summer temperatures and dry sandy soils where there is little competition (Parsons and Cuthbertson, 1992). Caltrop can also invade waste or highly disturbed parks (Parsons and Cuthbertson, 1992).

Distribution:



Original source via CABI


Invasiveness Assessment

ESTABLISHMENT


1. Germination requirements? “Seeds germinate after late spring and summer rains’. (P & C, 1992 p. 640)

2. Establishment requirements? Occurs in open areas (i.e. crops and pasture). (P & C, 1992 p. 640/41)

3. How much disturbance is required? Invades pastures and crops (e.g. vineyards, irrigated cotton). “Only in recent years has it invaded horticultural and agricultural crops and pastures”. (P & C, 1992 p. 641)

GROWTH / COMPETITIVE


4. Life form? Annual herb. Other. (P & C, 1992 p. 640)

5. Allelopathic properties? “There is evidence that Caltrop has an Allelopathic effect on some plants” (e.g. grass seedlings). (P & C, 1992 p. 642)

6. Tolerates herb pressure? “They do not normally graze Caltrop when other feed is available but, in some cases there is no alternative”. (P & C, 1992 p. 642)

7. Normal growth rate? Competes with pastures and a variety of crops throughout Australia. (e.g. cereals, cotton, vines and peanuts). (P & C, 1992 p. 641)

8. Stress tolerance to frost, drought, w/logg, sal. etc? Its extensive root system allows it to survive droughts. Its extensive distribution in Australia would allow it to tolerate some frost and likely other conditions. (P & C, 1992 p. 642; Map p. 640)

REPRODUCTION


9. Reproductive system? “Reproducing by seed”. (P & C, 1992 p. 640)

10. Number of propagules produced? “Fruit are thus formed continually throughout the summer and autumn and according to Indian studies up to 1,000 fruit can be produced on each plant”. (P & C, 1992 p. 641)

11. Propagule longevity? "Buried seed remains viable for several years”. (P & C, 1992 p. 641)

12. Reproductive period? Annual herb. (P & C, 1992 p. 640)

13. Time to reproductive maturity? “The first flowers may be formed when plants are only three weeks old and the first fruit at five or six weeks”. (P & C, 1992 p. 641)

DISPERSAL


14. Number of mechanisms? Animals, vehicle tyres, shoes and almost any object which is placed on it. (P & C, 1992 p. 641)

15. How far do they disperse? Animals, vehicles could easily disperse seeds numerous km.


Impact Assessment

RECREATION


1. Restrict human access? “A prostrate summer-growing annual herb.” Even in dense infestations, its presence does not hinder human access. (P & C, 2001)

2. Reduce tourism? Its presence is likely to affect recreational activities. The fruit is a woody burr with sharp rigid spines to about 6 mm long. It splits into five segments each with two spines. The spines on the fruit and segments can easily penetrate human flesh causing discomfort. Infestations may limit recreational activities. (P & C, 2001)

3. Injurious to people? The fruit and resultant segments present rigid spines to about 6 mm long. Fruit are formed continuously through the summer and autumn. In India, plants have produced up to 1,000 fruit. (P & C, 2001)

4. Damage to cultural sites? In dense infestations in NSW the plant is known to provide cover of up to 45 cm deep for several months of the year. Also, in shaded areas or when competing with taller plants the stems will grow erect. The physical structure of site is not affected, but dense infestations would seriously affect the aesthetics of an area. (P & C, 2001)

ABIOTIC


5. Impact flow? Terrestrial species. P & C (2001)

6. Impact water quality? Terrestrial species. P & C (2001)

7. Increase soil erosion? “It occurs mostly on dry sandy soils where there is little competition.” Its presence may help to reduce soil erosion marginally during its growth and flowering period. (P & C, 2001)

8. Reduce biomass? Grows best in disturbed areas with minimal vegetation. Invader replaces biomass. P & C (2001)

9. Change fire regime? A summer annual it adds little if any fuel load. Dry matter would present little or negligible effect on fire risk. (P & C, 2001)

COMMUNITY HABITAT


10(a) Impact on composition of high value EVC? EVC=Plains grassland (E); CMA=North Central; Bioreg=Victorian Riverina; VH CLIMATE potential “…caltrop is most frequently found in the north of the State…where it occurs in railway yards, nature strips, parks and waste areas in almost every town.” “Prefers dry sandy soils where there is little competition.” Allelopathic. Major displacement of grasses or ground covers. (P & C, 2001)

10(b) Impact on medium value EVC? It is not likely to occur in medium value EVCs.

10(c) Impact on low value EVC? It is not likely to occur in low value EVCs

11. Impact on structure? Grows best in disturbed areas with minimal other vegetation. It is reported to have allelopathic properties which inhibit the growth of grass seedlings, and its extensive root system can compete effectively for moisture and nutrients. In dense infestations it can dominate the ground flora. (P & C, 2001)

12. Effect on threatened flora?

FAUNA


13. Effect on threatened fauna?

14. Effect on non-threatened fauna? The areas where T. terrestris inhabit (railway yards, nature strips and waste areas) would not be a significant food source for grazing fauna. Its presence may have a minor effect in reducing food source. (P & C, 2001)

15. Benefits fauna? No known benefits.

16. Injurious to fauna? “Spines on the fruit damage the feet of animals.” When eaten, the fruit can damage the mouth and possibly the lining of the stomach and intestines. It is toxic to sheep and may present similar properties to native fauna. (P & C, 2001)

PEST ANIMAL


17. Food source to pests? Not known as food source to pests.

18. Provides harbor? A prostrate annual herb with spiny fruit, it is unlikely to provide habitat for pest animals. P & C (2001)

AGRICULTURE


19. Impact yield? A significant pest in crops, it is able to extract soil moisture from great depth. This allows it to offer severe competition under very dry conditions. In pasture situations, in the absence of other suitable fodder, animals will graze new growth of T. terrestris, which may cause stock losses. The level of impact is not documented but losses in New South Wales and Western Australia have been reported. (Holm et al 1978; P & C 2001)

20. Impact quality? It contaminates harvested product, particularly in the dried fruit industry, and is a vegetable fault in wool. However, presence of the seed does not affect wool processing. (P & C, 2001;
AWTA Ltd)

21. Affect land values? The weed causes some agricultural loss, but it can be readily controlled with suitable mechanical and chemical controls. Its presence may affect land value somewhat. (Holm et al 1978)

22. Change land use? The potential threat to grazing animals presented by the weed may dictate a temporary change to land use. In NSW grows exceptionally well on farms with a system of winter cereal crops and sheep grazing. A period of continuous cropping may be required until the weed is controlled. (P & C, 2001)

23. Increase harvest costs? Seeds and seed segments are a nuisance causing painful injury to fruit pickers and shearers. Continuous interruption (to remove the offending spine) may increase the time to harvest. (P & C, 2001)

24. Disease host/vector? None evident




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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.






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Date: 5 October 2009; 2:46:20 PM AEDT

Author Name: Jessica Mackay
Author ID: mackayj