Sagittaria platyphylla (Engelm) J. G. Sm.

Title: Sagittaria platyphylla (Engelm) J. G. Sm.

Scientific Name:

Sagittaria platyphylla (Engelm) J. G. Sm.

Common Names:

sagittaria, arrowhead

Source & more images (via ALA)

Habitat: Warm-temperate and subtropical shallowly flooded to about 45 cm or marshy areas associated with rivers and streams (Parsons and Cuthbertson, 1992). It is a weed of drainage ditches and permanent swamps associated with irrigation and drainage systems in south-eastern Australia (Parsons and Cuthbertson, 1992). Arrowhead invades permanent freshwater wetlands (Carr et al., 1992).

Distribution:

Original source via GBIF

Invasiveness Assessment

ESTABLISHMENT

1. Germination requirements? Seeds germinate as temperatures rise in spring. Rhizomes begin to form on seedlings about a month after germination (Parsons and Cuthbertson, 1992).

2. Establishment requirements? Establishes in ‘open’ habitats. (See ‘habitats’ notes) (Parsons and Cuthbertson, 1992).

3. How much disturbance is required? Establishes in highly disturbed natural ecosystems. E.g. irrigation channels and drainage systems associated with permanent swamps (Parsons and Cuthbertson, 1992).

GROWTH / COMPETITIVE

4. Life form? Emergent aquatic perennial herb (Parsons and Cuthbertson, 1992).

5. Allelopathic properties? None described.

6. Tolerates herb pressure? Spoonbills and carp have been observed feeding on the plant. Either or both of these animals may have been the cause of the plants disappearance on river flats along the River Murray. Small patches, however, reappeared (Black, 1987).

7. Normal growth rate? Sagittaria competes strongly with hydrilla (Parsons and Cuthbertson, 1992).

8. Stress tolerance to frost, drought, w/logg, sal. etc? Tolerates water logging and fire as occurs in aquatic habitats (Parsons and Cuthbertson, 1992).

REPRODUCTION

9. Reproductive system? Reproducing by seed, rhizomes and tubers (Parsons and Cuthbertson, 1992).

10. Number of propagules produced? “Hundreds of viable seeds produced from each flower” Champion (1995).

11. Propagule longevity? ?

12. Reproductive period? Forms dense monocultures. (See picture in Parsons and Cuthbertson, 1992 p. 35). (Parsons and Cuthbertson, 1992).

13. Time to reproductive maturity? Seeds germinate in spring and flowering stems appear in summer (Parsons and Cuthbertson, 1992).

DISPERSAL

14. Number of mechanisms? Some seeds are eaten by ducks and believed to be viable when excreted, while others may float some distance before sinking (Parsons and Cuthbertson, 1992).

15. How far do they disperse? Most seeds drop within the parent colony ( < 20 m ). However, some bird dispersed seeds may disperse > 1 km (Parsons and Cuthbertson, 1992).

Impact Assessment

RECREATION

1. Restrict human access? An emergent aquatic perennial herb. Inhabits shallowly flooded (to 45cm) or marshy areas associated with rivers and streams. In south eastern Australia it is commonly found in drainage ditches and permanent swamps associated with irrigation and drainage systems. Would not affect land-based activities (Parsons and Cuthbertson, 2001).

2. Reduce tourism? Although most commonly found in drainage ditches and irrigation canals, it has also been found in a number of creeks in Victoria including Nine Mile Creek, Wunghnu and Bullock Creek near the junction of the Oven and Murray Rivers. In drain and irrigation channels it can form dense infestations. Likewise, in similar slow-flowing creeks its presence may affect water-based activities such as fishing or swimming (Parsons and Cuthbertson, 2001).

3. Injurious to people? No known toxic or physical properties. Other tuber forming species such as S. sagittifolia are eaten by ducks and sometimes humans. Not harmful (Parsons and Cuthbertson, 2001).

4. Damage to cultural sites? An aquatic species. Not likely to occur in any site of cultural significance.

ABIOTIC

5. Impact flow? "Sagittaria grows in static or slow-moving freshwater such as drains, streams and pond margins, up to a depth of 45cm. [It] forms extensive infestations in shallow waterways, seriously restricting water flow and increasing sedimentation, thus aggravating flooding." An emergent aquatic, firmly rooted. Would have serious impact on surface and sub-surface flows in slow-moving water bodies. (Bay of Plenty; Parsons and Cuthbertson, 2001).

6. Impact water quality? In flowing water it occurs on stream margins and can obstruct flow. Its presence in Victoria, though well known, has not produced any reports of serious impact on water quality. Dense infestations may have a minor impact on dissolved O2 or light levels (Sainty and Jacobs, 1981).

7. Increase soil erosion? In New Zealand it, "forms extensive infestations in shallow waterways, seriously restricting water flow and increasing sedimentation, thus aggravating flooding." Increased chance of flooding would create the potential for large-scale soil movement with minor off-site implications (Bay of Plenty).

8. Reduce biomass? Where it occurs in drainage channels and irrigation canals little other vegetation would normally exist. Infestations of arrowhead would increase biomass (Parsons and Cuthbertson, 2001).

9. Change fire regime? Aquatic species. No effect on fire regime.

COMMUNITY HABITAT

10(a) Impact on composition of high value EVC? Aquatic species (Parsons and Cuthbertson, 2001).

10(b) Impact on medium value EVC? Aquatic species (Parsons and Cuthbertson, 2001).

10(c) Impact on low value EVC? Aquatic species (Parsons and Cuthbertson, 2001).

11. Impact on structure? It has the potential to, "…replace natural communities on stream margins." Potential to dominate native aquatic species (Champion, 1995).

12. Effect on threatened flora? This species is not documented as posing an additional risk to threatened flora.

FAUNA

13. Effect on threatened fauna? This species is not documented as posing an additional risk to threatened fauna.

14. Effect on non-threatened fauna? No known negative impacts on native fauna. See also comment in 15 below.

15. Benefits fauna? In South Australia, spoonbills have been observed digging up plants to get at the corms. The plant may provide an alternate source of food. (Note: It is believed that such predation led to the disappearance of an infestation along the Murray River in South Australia.) (Black, 1987).

16. Injurious to fauna? Spoonbills and carp have been observed feeding on the plant. Not harmful (Parsons and Cuthbertson, 2001).

PEST ANIMAL

17. Food source to pests? Carp have been observed feeding on the plant. (Consider a serious aquatic pest) (Parsons and Cuthbertson, 2001).

18. Provides harbor? Unlikely to provide any additional harbour not already available by native species.

AGRICULTURE

19. Impact yield? Aquatic species. Would not affect yield.

20. Impact quality? Aquatic species. Would not affect quality of produce.

21. Affect land values? Aquatic species. It may affect the value of irrigated land due to increased costs relating to keeping channels clear. Very minor.

22. Change land use? Aquatic species. Infestations are unlikely to affect land use.

23. Increase harvest costs? Aquatic species. The cost of keeping irrigation channels open may increase production costs, but not affect harvesting.

24. Disease host/vector? None documented.

Feedback

Do you have additional information about this plant that will improve the quality of the assessment? If so, we would value your contribution.

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

The entry of this assessment was made possible through the generous support of f Dr Robin Adair, Research Leader, Weed Sciences, Victorian Department of Primary Industries.

Attachments:

P1010623.jpg
saggitaria via ala.JPG
Capture.JPG

commented on by (2)

wra4343: re: Sagittaria graminea Michx.wra3988: re: Sagittaria graminea

referenced by (1)

wra702: Common Name - A (via arrowhead)

Article: wra3893 (permalink)
Categories: :wra:s, :wra:inv1, :wra:invmh, :wra:inv2, :wra:invml, :wra:inv3, :wra:inv4, :wra:invh, :wra:inv5, :wra:invl, :wra:inv6, :wra:inv7, :wra:inv8, :wra:inv9, :wra:inv10, :wra:invm, :wra:inv11, :wra:inv12, :wra:inv13, :wra:inv14, :wra:inv15, :wra:imp1, :wra:impl, :wra:imp2, :wra:impmh, :wra:imp3, :wra:imp4, :wra:imp5, :wra:imph, :wra:imp6, :wra:impml, :wra:imp7, :wra:imp8, :wra:imp9, :wra:imp10a, :wra:imp10b, :wra:imp10c, :wra:imp11, :wra:imp12, :wra:imp13, :wra:imp14, :wra:imp15, :wra:imp16, :wra:imp17, :wra:imp18, :wra:imp19, :wra:imp20, :wra:imp21, :wra:imp22, :wra:imp23, :wra:imp24
Date: 9 November 2009; 10:55:29 AM AEDT

Author Name: Michelle Heitch
Author ID: heitchm