Old Man’s Beard | Clematis Vitalba

California Pest Rating for
Clematis vitalba: Old man’s beard
               Ranunculales: Ranunculaceae
Pest Rating: A  |  Proposed Seed Rating: P

Initiating Event:

Old Man’s beard (Clematis vitalba) is listed as a B rated quarantine weed in Oregon and Class C noxious weed in Washington. In 2014, this species was added as new alert weed in California (Joe DiTomaso, UC Davis) and was listed on California Invasive Species Council’s watch list in December, 2015. It has been reported several times growing in Marin, Santa Cruz and San Francisco Counties recently. (Cal Flora: Distribution by County: Clematis vitalba). Due to this, a risk assessment of this known weed is critical to designate an official rating.

History & Status:

Old man’s beard is a broad leaved, deciduous, woody climbing vine that  lives up to 40 years (West, 1991). It grows to 65 feet long and acts as a ground cover in the absence of trees to climb. New shoots can grow 6 feet per year and older plants can grow 30 feet per year. (Kings county Noxious Weed Control Program). Old Man’s Beard is native to Europe, Africa and south west Asia. It has been introduced to and naturalized in North America, Australia and New Zealand. This plant is found on disturbed lands, forest edges and wooded areas with partial sun. It is also capable of growing on hedgerows, fence lines, dunes, riverbanks and grassland. Old man’s beard can easily invade riparian vegetation, waste land, tall grasses and disturbed urban areas. Since this plant grows on road sides, the seeds can be transported on vehicles from known infestations to new sites. The highest risk of introduction is through the intentional introduction of this plant as an ornamental, plants and seeds sold by nurseries, mail order and online sales (Invasive Species Compendium: CABI Database: Clematis vitalba). It is self-pollinated and can also be pollinated by wind or insects. Old man’s beard produces up to 100,000 seeds per plant per year. Seeds can remain viable for up to five years in the soil (Kings county noxious weed control program).

Official ControlOld man’s beard is recognized as a harmful organism in New Zealand and is listed as invasive weed in the United Kingdom and Canada. In the United States, it is recognized as invasive in Oregon, Washington and Maine (Invasive species compendium: CABI Database: Clematis vitalba). It is not yet fully established in California.

California DistributionOld man’s beard has been observed in limited areas of Marin, Santa Cruz and Santa Clara counties (Consortium of California Herbaria).

California InterceptionsOld man’s beard has not been intercepted in California through regulatory pathways (Pest and Damage Report Database, CA Department of Food and Agriculture), but has been reported to CDFA from National and State Park personnel.

United States:  Old man’s beard has a long history in North American Horticulture. It was first introduced into the US between 1830 and 1840 (ACS, 2003). Currently, it has a limited naturalized distribution in the states of Oregon, Maine, Washington and California (Invasive species compendium: CABI Database: Clematis vitalba).

International: Old man’s beard is native to Europe and is reported as naturalized in Ireland, Poland, Sweden, Norway and other areas bordering its native range.  It is also naturalized in parts of North America, Australia and New Zealand. (Invasive species compendium: CABI Database: Clematis vitalba)

The risk Old man’s beard would pose to California is evaluated below.

Consequences of Introduction: 

1) Climate/Host Interaction: Old man’s beard is a warm temperate species. It grows on well-drained, moderately fertile and moist soils. In gardens, it responds well to the application of lime, but it is not restricted to calcareous sites in the wild. It is generally found in areas where annual rain fall is greater than 800 mm. California coastal areas with moist soils and heavy precipitation during the winter months can be at a risk for this invasive plant to establish. Risk is Medium (2).

Evaluate if the pest would have suitable hosts and climate to establish in California.  Score: 2

– Low (1) Not likely to establish in California; or likely to establish in very limited areas.

– Medium (2) may be able to establish in a larger but limited part of California.

– High (3) likely to establish a widespread distribution in California.

2) Host Range: Old man’s beard is capable of growing in variety of habitats and on a number of substrates including trees and shrubs on forest margins, riverbanks, fence lines, dunes, hedgerows, grasslands and even in urban areas. (Invasive species compendium: CABI Database: Clematis vitalba). It has been observed recently near creeks, slopes and forest areas along California coast. Risk is High (3).

Evaluate the host range of the pest. Score: 3

– Low (1) has a very limited host range.

– Medium (2) has a moderate host range.

High (3) has a wide host range.

3) Pest Dispersal Potential: Old man’s beard is pollinated by wind and insects. It can produce up to 100,000 seeds per plant and seeds can remain viable up to five years. (Kings County Noxious Weed Control Program). Seeds can be spread by wind, water, humans and animals. It can also spread by fragmentation when roots are produced from both separated and attached stem fragments. This weed can be accidentally spread along road sides by turbulence created by moving motor vehicles. Additionally, it has been introduced intentionally as an ornamental plant (Invasive species compendium: CABI database: Clematis vitalba). Risk is High (3).

Evaluate the natural and artificial dispersal potential of the pest. Score: 3

– Low (1) does not have high reproductive or dispersal potential.

– Medium (2) has either high reproductive or dispersal potential.

High (3) has both high reproduction and dispersal potential.

4) Economic Impact:  Old man’s beard is a host of Alfalfa mosaic virus (Polak, 1986). There may be an increased risk of disease transmission by Clematis vitalba near vineyards. It has been regarded as a minor weed in European vineyards as well as a weed of pine plantations (Mitchell, 1975). Old man’s beard is poisonous to grazing livestock animals (West, 1991). Risk is High (3).

Evaluate the economic impact of the pest to California using the criteria below.

Economic Impact: A, B, E, F

A. The pest could lower crop yield.

B. The pest could lower crop value (includes increasing crop production costs).

C. The pest could trigger the loss of markets (includes quarantines).

D. The pest could negatively change normal cultural practices.

E. The pest can vector, or is vectored, by another pestiferous organism.

F. The organism is injurious or poisonous to agriculturally important animals.

G. The organism can interfere with the delivery or supply of water for agricultural uses.

Economic Impact Score: 3

– Low (1) causes 0 or 1 of these impacts.

– Medium (2) causes 2 of these impacts.

– High (3) causes 3 or more of these impacts.

5) Environmental Impact: Infestation with Old man’s beard reduces biodiversity by blocking the light and out-competing native plants and trees. This could cause extirpation of local species that have restricted distributions. Its vines can form a dense, light absorbing canopy that suppresses all vegetation it climbs. Its vigorous growth and heavy weight can break the trees beneath it, leaving previously heathy forest a low, long-lived thicket of vines. (Global Invasive Species Database). Damage from old man’s beard can enhance invasion of native habitats by other invasive plants. As it occurs on public land, its presence will lead to treatment programs. Risk is High (3).

Evaluate the environmental impact of the pest on California using the criteria below.

Environmental Impact: A, C, D

A. The pest could have a significant environmental impact such as lowering biodiversity, disrupting natural communities, or changing ecosystem processes.

B. The pest could directly affect threatened or endangered species.

C. The pest could impact threatened or endangered species by disrupting critical habitats.

D. The pest could trigger additional official or private treatment programs.

E. The pest could significantly impact cultural practices, home/urban gardening or ornamental plantings.

Environmental Impact Score: 3

– Low (1) causes none of the above to occur.

– Medium (2) causes one of the above to occur.

High (3) causes two or more of the above to occur.

Consequences of Introduction to California for Old man’s beard: High (14)

Add up the total score and include it here.

-Low = 5-8 points

-Medium = 9-12 points

High = 13-15 points

6) Post Entry Distribution and Survey Information: Old man’s beard has a limited distribution in Marin County and has been observed sparsely in Santa Cruz and San Francisco counties (Consortium of California Harbaria). Score: -1

Evaluate the known distribution in California. Only official records identified by a taxonomic expert and supported by voucher specimens deposited in natural history collections should be considered. Pest incursions that have been eradicated, are under eradication, or have been delimited with no further detections should not be included.

-Not established (0) Pest never detected in California, or known only from incursions.

-Low (-1) Pest has a localized distribution in California, or is established in one suitable climate/host area (region).

-Medium (-2) Pest is widespread in California but not fully established in the endangered area, or pest established in two contiguous suitable climate/host areas.

-High (-3) Pest has fully established in the endangered area, or pest is reported in more than two contiguous or non-contiguous suitable climate/host areas.

Final Score:

The final score is the consequences of introduction score minus the post entry distribution and survey information score: High (13)


Old man’s beard may not spread and get established in drier areas of California but has it has a strong ability to grow and spread in the coastal areas with ample moisture and higher than average precipitation. It has not yet spread to vineyards and pine plantations in California, but has done so in Europe.

Conclusion and Rating Justification:

Old man’s beard has been recognized as a threat in Oregon and Washington. The fact that it has been observed multiple times, growing in the areas of Marin and Santa Cruz counties indicates that it can spread and get established in coastal areas of the California. An “A” rating is proposed at this time for this invasive weed, as it can still be eradicated from California.


Plants Profile of Clematis vitalba (evergreen clematis), Accessed:10/06/2016 http://plants.usda.gov/core/profile?symbol=CLVI6

West CJ, 1991. Literature review of the biology of Clematis vitalba (old man’s beard). DSIR Land Resources Vegetation Report No. 725. Library@landcareresearch.co.nz.

Invasive Species Compendium- Clematis Vitalba, Accessed:10/06/2016 http://www.cabi.org/isc/datasheet/14280

Kings county Noxious Weed Control Program: Best Management Practices- Old Man’s Beard http://your.kingcounty.gov/dnrp/library/water-and-land/weeds/BMPs/Old-mans-beard-Clematis-vitalba-control.pdf

Plants for a Future: Clematis vitalba; Accessed: 10/06/2016 http://www.pfaf.org/user/Plant.aspx?LatinName=Clematis+vitalba

Cal Flora: Clematis vitalba; Accessed: 10/06/2016 http://www.calflora.org/cgi-bin/county_taxon.cgi?where-calrecnum=8710

Consortium of California Harbaria: Accessed 10/20/2016 http://ucjeps.berkeley.edu/consortium/

California Agriculture; University of California Agricultural and Natural Resources http://calag.ucanr.edu/Archive/?article=ca.v068n03p89

Global Invasive species database http://www.iucngisd.org/gisd/species.php?sc=157

Mitchell AF, 1975. Three forest climbers, Ivy, old man’s beard, and honeysuckle. Forestry Commission Forestry Record, HM Stationery Office, 1-12

Polak Z, 1996. Spontaneous hosts of alfalfa mosaic virus ascertained in ruderal plant associations in central Bohemia. Ochrana Rostlin, 32:161-165

Pest and Damage Records Database: Plant Health and Pest Prevention Services, California Department of Food and Agriculture, Assessed: 10/19/2016

Distribution of Climatis vitalba: Discover Life: Global Mapper- Global Biodiversity Information Facility. http://www.discoverlife.org/mp/20m?kind=Clematis+vitalba


Responsible Party:

Raj Randhawa, Senior Environmental Scientist; Dean G. Kelch, Primary Botanist; California Department of Food and Agriculture; 1220 N Street, Sacramento, CA 95814; Tel. (916) 654-0312; plant.health[@]cdfa.ca.gov.

Pest Rating: A  |  Proposed Seed Rating: P

Posted by ls