Cytisus multiflorus (L.' Hér. ex Aiton) Sweet

Title: Cytisus multiflorus (L.' Hér. ex Aiton) Sweet

Scientific Name:

Cytisus multiflorus (L.' Hér. ex Aiton) Sweet

Common Name:

white Spanish broom

Source & more images (via CABI)

Habitat: In Victoria, this plant naturalised following an ornamental planting on a lakeside in central Victoria. It has since spread along roadsides and into townships (Weeds CRC). In New Zealand, it occurs on the South Island in dry waste places, scrubland and riverbeds (Webb et al 1988). Within its native range in the Mediterranean region it occurs as one of the representative species in woodlands and scrublands (Rodriguez-Riaño et al 2004).

Distribution:

Original source via GBIF

Invasiveness Assessment

ESTABLISHMENT

1. Germination requirements? "The seeds germinate with autumn rains and during spring." Responds to natural season disturbances; autumn rain, and spring rainfall and temperatures (Weeds CRC, 2003).

2. Establishment requirements? "…white Spanish broom is hard seeded and the seeds remain viable for a long time in the soil." As with the related C. scoparius, it is likely that germination will occur only after the hard seed coat is damaged by fire, or some abrasive action (e.g. disturbance due to animal digging). In New Zealand, C. multiflorus occurs in dry waste places, scrubland, and riverbeds. Possibly requires access to light and direct rainfall (Weeds CRC, 2003).

3. How much disturbance is required? "As a weed, it is known to enter relatively undisturbed bushland. In Australia it has spread from lakeside plantings into roadsides and townships." Potential to establish in areas subject to minor disturbance (Weeds CRC, 2003).

GROWTH / COMPETITIVE

4. Life form? Perennial shrub ⇒ Other (Webb et al. 1988).

5. Allelopathic properties? None described. A nitrogen-fixing plant, it may inhibit the growth of some native species by changing the soil chemistry (Weeds CRC, 2003).

6. Tolerates herb pressure? A study on the consumption of a related broom, C. scoparius, by both vertebrate and invertebrate herbivores found that the growth or reproductive capacity is not affected. It appears the same result may be applied to C. multiflorus. (It is a common practice in other research or extension material to compare or combine these species.) Not eaten by animals/insects; not under a biological control program in Victoria (Bossard & Rejmane, 1994).

7. Normal growth rate? C. multiflorus will grow at the same or similar rate to other native and exotic leguminous species (Perez-Fernandez & Lamont, 2002)

8. Stress tolerance to frost, drought, w/logg, sal. etc? Occurs in dry sclerophyll forest and woodland ⇒ tolerates dry weather: somewhat drought resistant. In cultivation in the U.S., it is noted as having a hardiness rating of 6 to 10 (-23°C to 2°C). Likely to survive mild frosts in Australia. "Many dry-fruited shrubs form highly resilient thickets because of their pyrophilous (fire-loving) nature." Plants able to withstand low-intensity fire (Carr et al., 1992; Page & Olds, 1998; Malo, 2004).

REPRODUCTION

9. Reproductive system? Sexual reproduction. Cross-pollination only (Rodriguez-Riaño et al., 2004)

10. Number of propagules produced? "Cytisus multiflorus is a winter-flowering species in the study population and produces a great number of white flowers per plant (range = 8259–15228), [but]…the final crop of seeds and fruit was sparse." Fruit set ≈ 23%: 2 seeds/fruit ⇒ 7,000 seeds (Rodriguez-Riaño et al., 2004).

11. Propagule longevity? "Like many legumes, white Spanish broom is hard seeded and the seeds remain viable for a long time in the soil, probably as long as the seed of the closely related C. scoparius, which is still viable 20 years after being dropped." (Weeds CRC, 2003).

12. Reproductive period? No data are available on the life span of this species. As with other broom species, it is possible that C. multiflorus would produce propagules for a period of 5 to 10 years or possibly longer. It is noted that the related C. scoparius can live for up to 27 years (Muyt, 2001)

13. Time to reproductive maturity? Seeds produced from the third year (Weeds CRC, 2003).

DISPERSAL

14. Number of mechanisms? The main mechanism for dispersal is the explosive pods that eject the seed. As with other brooms, rainwater and erosion may move some seeds over much greater distance. However, the role of humans in dispersal of this attractive plant should not be discounted (Malo, 2004).

15. How far do they disperse? Seedpods eject the seed, but most fall near to the maternal plant. "Under natural conditions, over 60% of C. multiflorus seeds are dispersed less than 1 m from the edge of the plant and less than 15% reach beyond 3 m." The abiotic dispersal of seed from such Mediterranean shrubs appears to allow only for the colonisation of peripheral areas around the scrub patches. "The above-mentioned case of C. multiflorus and the published data on Cistus ladanifer strengthen the idea of minimal abiotic dispersal of dry-fruited shrubs typical in pioneer Mediterranean scrubland." (Weeds CRC, 2003; Malo, 2004).

Impact Assessment

RECREATION

1. Restrict human access? Large shrub to 3 metres high; infestations can create a dense scrub layer. More commonly occurring in disturbed places such as roadsides. As it likely to establish in undisturbed habitats, such as grasslands and woodlands, dense infestations would inhibit pedestrians. Dense stands are impenetrable (Weeds CRC, 2003; Blood pers. com. ).

2. Reduce tourism? The plant produces abundant white, sweet-scented flowers from September to November, which the 'average' visitor may find attractive. It is unlikely to inhibit recreational pursuits except where it may occur as a dense patch beside or near a waterbody. Minor effect; visitors would be aware of the plant, but not greatly bothered by its presence (Weeds CRC, 2003).

3. Injurious to people? Seeds are poisonous. Produces a great number of seeds most of which fall near to the parent plant. Toxic properties at most time of the year (Weeds CRC, 2003; Rodriguez-Riaño et al., 2004; Malo, 2004).

4. Damage to cultural sites? "Dense broom stands shade out native herbaceous groundcover plants and eucalypt seedlings." Changes to vegetation structure may create a moderate negative visual effect (Weeds CRC, 2003).

ABIOTIC

5. Impact flow? Terrestrial sp. Occurs in dry sclerophyll forest and woodland (Carr et al., 1992).

6. Impact water quality? Terrestrial species.

7. Increase soil erosion? "[Brooms] have been widely used as ornamental landscape plants and also for wasteland reclamation (e.g. mine tailings) and sand dune stabilisation." Although the distribution of white Spanish broom in Victoria is limited, within infestations it is known to occur in medium to large populations. Likely to enhance soil stabilisation in neglected or waste areas. Low probability of large-scale soil movement (Wikipedia; Carr et al., 1992).

8. Reduce biomass? "…it could also establish in a wide range of disturbed and undisturbed habitats such as grasslands and open eucalypt woodlands." Dense infestations may lead to a slight increase in biomass (Weeds CRC, 2003).

9. Change fire regime? Its contribution to fuel load and flammability are not documented. In Victoria, it occurs in dry sclerophyll forest and woodland; observed growing in conjunction with English broom and gorse. Influence on fire regime in these situations would be minimal (Carr et al., 1992; Blood, pers. com.; Hansford, pers. com.) .

COMMUNITY HABITAT

10(a) Impact on composition of high value EVC? EVC=Heathy Woodland (V); CMA=North Central; Bioreg=Goldfields; VH CLIMATE potential. The dense habit of the shrub produces deep shade that would affect ground covers and forbs. It may also affect the regeneration of native overstorey species. Potential for major displacement of some dominant spp. within
different layers (Weeds CRC, 2003).

10(b) Impact on medium value EVC? EVC=Box Ironbark Forest (D); CMA=North Central; Bioreg=Goldfields; VH CLIMATE potential. Impact as in 10(a) above.

10(c) Impact on low value EVC? EVC=Heathy Dry Forest (LC); CMA=North Central; Bioreg=Goldfields; VH CLIMATE potential. Impact as in 10(a) above.

11. Impact on structure? At Creswick in Victoria, it occurs with other invasive shrubs (English broom, gorse), on roadsides and some private land. The dense habit of the shrub produces deep shade that would affect ground covers and forbs. It may also affect the regeneration of native overstorey species. Major effect on < 60% of the lower and mid storeys (Weeds CRC, 2003; Blood, pers. com.; Hansford, pers. com.).

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? Reduction in native groundcovers or forbs reducing food source for native spp. Minor effect due to reduction in food (Weeds CRC, 2003).

15. Benefits fauna? No benefits documented.

16. Injurious to fauna? The seeds are known to be poisonous, however, consumption by native herbivores is not documented (Weeds CRC, 2003).

PEST ANIMAL

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

18. Provides harbor? It is considered to provide shelter for feral animals, though the species are not documented. The dense habit of the shrub may provide harbour for pest birds such as blackbirds. Similar to Scotch broom, C. scoparius, it may possibly provide harbour for feral pigs (Weeds CRC, 2003; Parsons & Cuthbertson, 2001).

AGRICULTURE

19. Impact yield? "In pastures, white Spanish broom forms thickets that prevent grazing and restrict access to water." However, the more aggressive C. scoparius is not known to be a problem in pasture; certainly not in cropping. Likely to have a limited impact on yield (e.g. by reducing carrying capacity) (Weeds CRC, 2003; Parsons & Cuthbertson, 2001).

20. Impact quality? Not likely to affect the quality of produce. Not a seed contaminant. (Large seed would be easily removed during processing.)

21. Affect land values? As with C. scoparius, it is unlikely to be a significant agricultural weed, thus it would have an immeasurable affect on the value of agricultural land (Parsons & Cuthbertson, 2001).

22. Change land use? No. Not likely to be a significant weed on managed farms. Potentially, it could be a problem on abandoned pasture.

23. Increase harvest costs? No

24. Disease host/vector? None documented. No other brooms are known to be hosts or vectors of disease.

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:

Cytisus_multiflorus_potential.pdf
Cyt_mul present.pdf
broom via ala.JPG
Capture.JPG

commented on by (1)

wra4463: re: Cytisus multiflorus (L.' Hér.) Sweet

referenced by (1)

wra1040: Common Name - W (via white spanish broom)

Article: wra3949 (permalink)
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Date: 9 November 2009; 11:10:56 AM AEDT

Author Name: David Low
Author ID: adminDavid