Marrubium vulgare L.

Title: Marrubium vulgare L.

Scientific name:

Marrubium vulgare L.

Common name(s):

horehound, white horehound

Source & more images (via ALA)

Habitat: Waysides and waste places in semi-arid to humid temperate regions, growing on well drained soils. It commonly occurs along fence lines, roadsides, channel banks, around buildings, on sheep camps and neglected urban areas, but under favourable conditions it invades pastures and occasionally cropping land (Parsons and Cuthbertson, 1992). Horehound invades dry coastal vegetation, mallee shrubland, lowland grassland & grassy woodlands, rock outcrop vegetation (Carr et al. 1992).

Distribution:

Original source via CABI

Invasiveness Assessment

ESTABLISHMENT

1. Germination requirements? “Most seeds germinate after autumn rains but some germination also occurs through winter and spring” (Parsons and Cuthbertson, 1992 p. 497).

2. Establishment requirements? “Tolerates full sun, shade of woodland canopy” (Blood, 2001 p. 152)

3. How much disturbance is required? Invades Mallee communities as well as red gum, black box and grassy woodland, dry coastal vegetation (Carr et al, 1992; Blood, 2001 p. 152).

GROWTH / COMPETITIVE

4. Life form? Perennial herb. Other. (Parsons and Cuthbertson, 1992 p. 497)

5. Allelopathic properties? None described.

6. Tolerates herb pressure? “Because of its bitter taste, horehound is not palatable to stock and is therefore, encouraged by heavy grazing” (Parsons and Cuthbertson, 1992 p. 499).

7. Normal growth rate? “Able to establish without competition. In contrast, seedlings do not establish in dense pastures”. “Young seedlings are not very competitive but, once established, they make rapid growth” (Parsons and Cuthbertson, 1992 p. 497).

8. Stress tolerance to frost, drought, w/logg, sal. etc? “Horehound is relatively drought tolerant” (Parsons and Cuthbertson, 1992p. 499). May be tolerant of some water logging if occurs in channel banks. “Tolerates drought and frost” (Blood, 2001 p. 152).

REPRODUCTION

9. Reproductive system? Reproducing by seed (Parsons and Cuthbertson, 1992 p. 497).

10. Number of propagules produced? “Mature plants can produce over 20,000 seeds per year” (Blood, 2001 p. 153).

11. Propagule longevity? “May survive in soil for 7-10 years” (Blood, 2001 p. 153).
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12. Reproductive period? Perennial herb. “New growth is produced each year in autumn and spring” (Parsons and Cuthbertson, 1992).

13. Time to reproductive maturity? “Plants may or may not flower in the first year, depending mainly on soil fertility” (Parsons and Cuthbertson, 1992).

DISPERSAL

14. Number of mechanisms? Burr attaches to wool, fur, bag, clothing, etc.: water; “and horses are known to pass the seeds in a viable condition” (Parsons and Cuthbertson, 1992 p. 498).

15. How far do they disperse? Also burrs attached to sheep responsible for much spread in Australia. “and horses are known to pass the seeds in a viable condition” (Parsons and Cuthbertson, 1992 p. 498).

Impact Assessment

RECREATION

1. Restrict human access? A bushy perennial herb, 30 cm tall and 75 cm wide. In dense infestations, its growth habit may present a minor nuisance to pedestrian traffic (Blood, 2001).

2. Reduce tourism? A low growing plant (30 cm); dense patches would have a minor effect on aesthetics, recreational activities not seriously affected (Parsons and Cuthbertson, 2001).

3. Injurious to people? The plant is not toxic, but the fruit has 10 backward-curved hooked spines; not known to be harmful or cause injury (Parsons and Cuthbertson, 2001).

4. Damage to cultural sites? Roots or growth habit unlikely to cause structural damage. Dense patches would create a moderate negative visual impact on a cultural site (Blood, 2001).

ABIOTIC

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

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

7. Increase soil erosion? In one area in Victoria where horehound has flourished, soil erosion has increased markedly (Parsons and Cuthbertson, 2001).

8. Reduce biomass? Generally invades neglected areas such as fence lines, roadsides, channel banks, around buildings, on sheep camps and neglected urban areas (Parsons and Cuthbertson, 2001). Biomass would increase.

9. Change fire regime? Bushy perennial. Increase in biomass would likely cause an increase in the intensity of fire risk (Moerkerk, 2000).

COMMUNITY HABITAT

10(a) Impact on composition of high value EVC? EVC=Plains grassy woodland (E); CMA=North Central; Bioreg=Goldfields; VH CLIMATE potential Prefers open areas. “…has the potential for dense establishment.” “Seedlings do not establish in dense pastures.” Impact lessened with overstorey cover. Major displacement of grasses/forbs (Parsons and Cuthbertson, 2001; Moerkerk, 2000).

10(b) Impact on medium value EVC? EVC=Riverine grassy woodland (D); CMA=Goulburn Broken; Bioreg=Murray Fans; VH CLIMATE potential Impact as in 10(a) above (Parsons and Cuthbertson, 2001; Moerkerk, 2000).

10(c) Impact on low value EVC? EVC=Rocky outcrop shrubland (LC); CMA=Wimmera; Bioreg=Central Victorian Uplands; VH CLIMATE potential. Impact as in 10(a) (Parsons and Cuthbertson, 2001; Moerkerk, 2000).

11. Impact on structure? “Has the potential to establish in pastures and open areas as dense monocultures.” It is present in Victoria in medium to large populations. Monoculture in lower stratum (Moerkerk, 2000; Carr et al, 1992).

12. Effect on threatened flora?

FAUNA

13. Effect on threatened fauna?

14. Effect on non-threatened fauna? In Victoria it is widespread in medium to large populations and invades dry coastal vegetation, mallee shrubland, lowland grassland & grassy woodland, and rock outcrop vegetation. “Because of its bitter taste, horehound is not palatable to stock.” “Horehound is relatively drought tolerant and has the potential for dense establishment in many more areas of Australia.” This plant would reduce the habitat for fauna species (Carr et al., 1992; Parsons and Cuthbertson, 2001).

15. Benefits fauna? No benefits apparent.

16. Injurious to fauna? Burrs are not injurious; no toxic properties (Parsons and Cuthbertson, 2001).

PEST ANIMAL

17. Food source to pests? Not known as a food source to pest animals.

18. Provides harbor? A low growing plant (30 cm tall) it may provide limited harbor for rodents or rabbits in low densities. The plant does occur near rabbit warrens mainly due to the seeds sticking to the animal’s fur (Parsons and Cuthbertson, 2001).

AGRICULTURE

19. Impact yield? In pasture, each plant occupies a large area thus reducing grazing considerably (Parsons and Cuthbertson, 2001).

20. Impact quality? “The meat of animals forced to eat it is tainted with a strong flavour.” (Blood, 2001). Minor impact on the quality of product. “The burrs become matted in wool and are difficult to remove, causing a loss in value of the fleece.” (Parsons and Cuthbertson, 2001).

21. Affect land values? Although infestations can be readily controlled with appropriate management techniques such as repeated cultivation, the presence of the weed, “… impacts on agricultural productivity.” (DPIWE Tas). It may reduce the value of land somewhat.

22. Change land use? “Ideally, the pasture should not be grazed in its first year in order to give maximum competition to any horehound seedlings.” Temporary reduction in agricultural activity (Parsons and Cuthbertson, 2001).

23. Increase harvest costs? No known impact on harvesting costs.

24. Disease host/vector? None evident.

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 The Weed's Network.

Attachments:

tn_horehound_plant.jpg
tn_horehounds.jpg
tn_horehound_flowerhead.jpg
horehound via ala.JPG
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referenced by (2)

wra1040: Common Name - W (via white horehound)wra1002: Common Name - H (via horehound)

Article: wra2342 (permalink)
Categories: :wra:m, :wra:inv1, :wra:invmh, :wra:inv2, :wra:inv3, :wra:invh, :wra:inv4, :wra:invl, :wra:inv5, :wra:inv6, :wra:inv7, :wra:invml, :wra:inv8, :wra:inv9, :wra:inv10, :wra:inv11, :wra:inv12, :wra:inv13, :wra:inv14, :wra:inv15, :wra:imp1, :wra:impl, :wra:imp2, :wra:impml, :wra:imp3, :wra:imp4, :wra:imp5, :wra:imp6, :wra:imp7, :wra:impmh, :wra:imp8, :wra:imp9, :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: 19 October 2009; 4:56:21 PM AEDT

Author Name: Jessica Mackay
Author ID: mackayj