English Holly

English Holly

Ilex aquifolium

Holly-fruit-K.-Newell
Status in Squamish:
CONTAIN
Status in Whistler:
PREVENTION-WATCHLIST
Status in Pemberton:
PREVENTION-WATCHLIST
 Vectors of Spread: 

         

ID Characteristics

General: A hardy perennial evergreen shrub with a single trunk or multiple stems. It is often used in landscapes as well as in decorations, floral decorations and as an ornamental during Christmas, hence it’s nickname “Christmas Holly”. English Holly plants can live over 250 years, and 10 year-old plants show a low mortality rate and accelerated growth.

Flowers: Are small, four-lobed, white, inconspicuous and sweetly scented.

Stem: Are erect, with spreading branches. Young plants have green bark, while mature plants can grow to be between 5 m to 15 m tall and have smooth, grey-silver bark.

Leaves: Are dark green, glossy, leathery, alternate, evergreen and egg-shaped, 2.5 – 6 cm long. Young leaves have stiff, sharp spines on the leaf margins; mature leaves may have smooth leaf margins and fewer spines, if at all.

Fruits: Are round, smooth, bright red or orange berries, 7 – 8 mm wide. Caution: Berries are poisonous to humans and pets.

Seeds: Berries grow in clusters and contain 2 – 8 seeds each.

Roots: Woody and long.

Similar Species

Native:

Tall Oregon Grape (Mahonia aquifolium) is also an evergreen shrub and boasts similar leaf characteristic that English Holly does, with sharp spines along the leaf margins. It has a longer blooming period, displaying bright yellow flowers; moreover, it can grow up to 2.5 m tall.

 

Report

Please report any sighting of English Holly by clicking here.

Habitat and Origin

English Holly originates from the British Isles and from Southern and Central Europe.

English Holly is adaptable to a wide range of soil, moisture, temperature and light conditions. New plants are often found in mixed deciduous forests, wetlands and near residential areas. It can survive in both sunny and shady conditions and grows best in sandy or well-drained soils.

Distribution

Propagation and Vectors of Spread

English Holly reproduces by seed as well as vegetatively by suckering (sending up shoots from the roots) and layering (growing the roots from where stems touch the ground).

Long distance dispersal is generally done by birds that eat the English Holly berries. Short distance spread is typically done by vegetative reproduction.

Holly is also spread by nursery sales, as it is a popular holiday decoration.

Economic and Ecological Impacts

Ecological:

  • Out-competes native plants:
    • Forms dense monocultures;
    • Suppresses germination and growth of native plants;
    • Creates deep shade which deprives native plants of light;
    • Roots leech nutrients and water from soil, which discourages other plants from growing in its vicinity;
    • Modifies soil conditions by adding organic matter and sulfur, which makes it difficult for native plants to thrive.
  • Unpalatable to ungulates.

Health:

  • Berries are poisonous to humans and pets.
What Can I Do?

Since English Holly is found in Squamish, the best approach to controlling the spread north is PREVENTION.

Learn to identify English Holly: use the images presented in this profile page to learn how to identify English Holly.

What to do if you spot it: You can report any English Holly sighting by clicking here.

DO:

  • Regularly monitor properties for weed infestations.
  • Ensure soil and gravel is free of English Holly before transporting.
  • Ensure plants (particularly flowering heads, berries or root fragments) are bagged or covered to prevent spread during transport to designated disposal sites (e.g. landfill).

DO NOT:

  • Purchase English Holly from nurseries for garden use.
  • Plant English Holly.
  • Unload, park, or store equipment or vehicles in infested areas; remove plant material from any equipment, vehicles, or clothing used in such areas and wash equipment and vehicles at designated cleaning sites before leaving infested areas.

Control

Mechanical Control

  • Hand-pull small plants when the soil is moist. Larger plants may be pulled or dug out using a manually-operated tool, or excavated.
  • Ensure the entirety of the root system is removed whenever possible, but be prepared to repeatedly treat the site.
  • For larger plants, it may be helpful to cut down the above-ground vegetation before digging the roots out.
  • Remove the roots and stems from the site and dispose of them to prevent the cut holly from suckering and re-rooting.
  • To avoid scratches or injury from the prickly leaves, wear eye protection, long pants, long sleeves, sturdy footwear and work gloves when working around English Holly.

Chemical Control

The application of herbicides such as glyphosate, imazapyr or triclopyr to cut stumps is an effective chemical control method. Glyphosate can also be applied using stem injection or foliar application. However, English Holly’s preference for riparian habitats makes the use of chemical control extremely difficult.

We recommend that any herbicide application is carried out by a person holding a valid BC Pesticide Applicator Certificate. Before selecting and applying herbicides, you must review and follow herbicide labels and application rates; municipal, regional, provincial and federal laws and regulations; species-specific treatment recommendations, and site-specific goals and objectives.

Biological Control

There is no biocontrol agent available at this time.

References

Coastal Invasive Species Committee, English Holly, https://www.coastalisc.com/english-holly/

eFlora, Tall Oregon Grape, http://linnet.geog.ubc.ca/Atlas/Atlas.aspx?sciname=Mahonia%20aquifolium

Invasive Plants Atlas, English Holly, https://www.invasiveplantatlas.org/subject.html?sub=5744

Invasive Species Council of British Columbia, English Holly, https://www.invasiveplantatlas.org/subject.html?sub=5744

Invasive Species Council of Metro Vancouver and Metro Vancouver, Best Management Practices for English Holly in the Metro Vancouver Region, http://www.metrovancouver.org/services/regional-planning/PlanningPublications/EnglishHollyBMP.pdf

King County Government, English Holly, https://www.kingcounty.gov/services/environment/animals-and-plants/noxious-weeds/weed-identification/english-holly.aspx

Noxious Weeds Control Board of Washington, English Holly, https://www.nwcb.wa.gov/weeds/english-holly