Rhamnus cathartica

Birds and mice eat the fruits of Rhamnus cathartica, which facilitates the long-distance dispersal of the seeds. This species can invade areas and become problematic. As a non-native understory shrub species, Rhamnus cathartica individuals leaf out very early and retain their leaves late in the growing season, causing the shading out of native wildflowers and herbaceous species.
Photo Credit: © Jan Samanek, State Phytosanitary Administration, Bugwood.org.
Rhamnus cathartica
Common Name: common buckthorn
Other Common Names: Carolina buckthorn, European buckthorn, European waythorn, Hart's thorn, nerprun cathartique
Plant Functional Group: Deciduous broadleaf
Class > Order > Family: Magnoliopsida > Rosales > Rhamnaceae
What does the species look like?

Common buckthorn is a deciduous, large shrub to small tree growing 3.3 to 25 feet tall. Male and female flowers generally occur separately on different plants, although the plants occasionally have flowers with both male and female parts. The small, rather inconspicuous, light yellowish-green to yellowish-brown flowers are grouped into clusters along the branches. Depending on the sunlight received at a site, flowering begins when plants mature from a few years to 20 years of age. They are insect-pollinated.

Common buckthorn occurs in moist to moderately moist areas, and occasionally on drier sites, such as roadsides, fields, thickets, woods, and wood edges. This species prefers lightly shaded sites, yet are also found in full sun. It tolerates many soil types, from well-drained sand and clay, to poorly drained calcareous soils, neutral to alkaline, and tolerates drought and air pollution.
Where is the species found?
States & Provinces
AB, CA, CO, CT, DE, IA, ID, IL, IN, KS, KY, MA, MB, MD, ME, MI, MN, MO, MT, NB, NC, ND, NE, NH, NJ, NS, NY, OH, ON, PA, PE, QC, RI, SD, SK, TN, UT, VA, VT, WI, WV, WY
Special Considerations for Observing

If drought seems to be the cause of leaf color or fall for a plant, please make a comment about it for that observation.

This species has separate male and female flowers. If you know whether the flowers you are observing are male or female (or both), please make a comment about it for that observation.

Note that individuals of this species with only male flowers will not produce fruit.
Which phenophases should I observe?
Do you see...?
Leaves Breaking leaf buds
One or more breaking leaf buds are visible on the plant. A leaf bud is considered "breaking" once a green leaf tip is visible at the end of the bud, but before the first leaf from the bud has unfolded to expose the leaf base at its point of attachment to the leaf stalk (petiole) or stem.
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How many buds are breaking?

  • Less than 3
  • 3 to 10
  • 11 to 100
  • 101 to 1,000
  • 1,001 to 10,000
  • More than 10,000
Leaves
One or more live, unfolded leaves are visible on the plant. A leaf is considered "unfolded" once its entire length has emerged from a breaking bud, stem node or growing stem tip, so that the leaf base is visible at its point of attachment to the leaf stalk (petiole) or stem. Do not include fully dried or dead leaves.
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What percentage of the potential canopy space is full with leaves? Ignore dead branches in your estimate of potential canopy space.

  • Less than 5%
  • 5-24%
  • 25-49%
  • 50-74%
  • 75-94%
  • 95% or more
Increasing leaf size
A majority of leaves on the plant have not yet reached their full size and are still growing larger. Do not include new leaves that continue to emerge at the ends of elongating stems throughout the growing season.
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What percentage of full size are most leaves?

  • Less than 25%
  • 25-49%
  • 50-74%
  • 75-94%
  • 95% or more
Colored leaves
One or more leaves show some of their typical late-season color, or yellow or brown due to drought or other stresses. Do not include small spots of color due to minor leaf damage, or dieback on branches that have broken. Do not include fully dried or dead leaves that remain on the plant.
More...

What percentage of the potential canopy space is full with non-green leaf color? Ignore dead branches in your estimate of potential canopy space.

  • Less than 5%
  • 5-24%
  • 25-49%
  • 50-74%
  • 75-94%
  • 95% or more
Falling leaves
One or more leaves with typical late-season color, or yellow or brown due to other stresses, are falling or have recently fallen from the plant. Do not include fully dried or dead leaves that remain on the plant for many days before falling.
More...


Flowers Flowers or flower buds
One or more fresh open or unopened flowers or flower buds are visible on the plant. Include flower buds or inflorescences that are swelling or expanding, but do not include those that are tightly closed and not actively growing (dormant). Also do not include wilted or dried flowers.
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How many flowers and flower buds are present? For species in which individual flowers are clustered in flower heads, spikes or catkins (inflorescences), simply estimate the number of flower heads, spikes or catkins and not the number of individual flowers.

  • Less than 3
  • 3 to 10
  • 11 to 100
  • 101 to 1,000
  • 1,001 to 10,000
  • More than 10,000
Open flowers
One or more open, fresh flowers are visible on the plant. Flowers are considered "open" when the reproductive parts (male stamens or female pistils) are visible between or within unfolded or open flower parts (petals, floral tubes or sepals). Do not include wilted or dried flowers.
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What percentage of all fresh flowers (buds plus unopened plus open) on the plant are open? For species in which individual flowers are clustered in flower heads, spikes or catkins (inflorescences), estimate the percentage of all individual flowers that are open.

  • Less than 5%
  • 5-24%
  • 25-49%
  • 50-74%
  • 75-94%
  • 95% or more
Fruits Fruits
One or more fruits are visible on the plant. For Rhamnus cathartica, the fruit is berry-like and changes from green to black.
More...

How many fruits are present?

  • Less than 3
  • 3 to 10
  • 11 to 100
  • 101 to 1,000
  • 1,001 to 10,000
  • More than 10,000
Ripe fruits
One or more ripe fruits are visible on the plant. For Rhamnus cathartica, a fruit is considered ripe when it has turned black.
More...

What percentage of all fruits (unripe plus ripe) on the plant are ripe?

  • Less than 5%
  • 5-24%
  • 25-49%
  • 50-74%
  • 75-94%
  • 95% or more
Recent fruit or seed drop
One or more mature fruits or seeds have dropped or been removed from the plant since your last visit. Do not include obviously immature fruits that have dropped before ripening, such as in a heavy rain or wind, or empty fruits that had long ago dropped all of their seeds but remained on the plant.
More...

How many mature fruits have dropped seeds or have completely dropped or been removed from the plant since your last visit?

  • Less than 3
  • 3 to 10
  • 11 to 100
  • 101 to 1,000
  • 1,001 to 10,000
  • More than 10,000
What do these phenophases look like?

The following Phenophase Photo Guides for this species have been vetted for accuracy by the USA-NPN National Coordinating Office. Most photo guides are developed for a particular local or regional monitoring effort, and some of the content may not apply to your effort or your region. However, we make them available to provide as much help as they may in illustrating phenophases for this species. If you have high quality phenophase photos that you are willing to share with us, please visit the Phenophase Photo Guidelines page.

Be aware there is variation from individual to individual within a species, especially across different regions, so your plant may not look exactly like the one pictured.

Since they do not always include complete definitions for the species, use these photo guides ONLY in conjunction with the official Nature's Notebook phenophase defintions included in the table above, in the phenophase definition sheet that downloads with the datasheet, or in the Observe screen in the mobile app.

USDA PLANTS profile for common buckthorn (USDA Symbol: RHCA3 )