Frangula alnus Mill., Rhamnaceae

Click on an image for links to BIGGER PICTURES

Present on Pacific Islands?  no

Primarily a threat at high elevations?  no

Risk assessment results:  High risk; score: 7.5 (Hawaii-Pacific Weed Risk Assessment for Frangula alnus)

Other Latin names:  Rhamnus frangula L.

Common name(s): [more details]

English: alder buckthorn, frangula, glossy buckthorn

Habit:  shrub

Description:  "A many-stemmed shrub or small tree up to 6 m tall, with a grey-brown bark and the young branches pubescent. Leaves are opposite, obovate, 3-7 cm long, entire, dark green above and light green and sometimes pubescent beneath. Petioles are 6-12 mm long. Each leaf has 7-9 pairs of veins. Small and greenish flowers are borne solitary or in axillary clusters of 2-10 on the current season's twigs. Pedicels are 8-12 mm long. Fruits are globose drupes of 6-10 mm diameter, red at first, becoming black. Each fruit contains two seeds of 4-5 mm diameter." (Invasive Plants of the World (Weber, 2003), p. 172)

Habitat/ecology:  "Native habitats of this shrub include moist open forests, heathland, riparian forests, and bogs. Where invasive, the shrub spreads rapidly and crowds out native woody and herbaceous plants. It is intolerant of heavy shade and becomes dominant at forest edges and in cleared areas. It is a prolific seed producer and seeds are dispersed by birds and small mammals. Seeds can remain viable in the soil for several years. Cut or otherwise damaged plants resprout vigorously." (Invasive Plants of the World (Weber, 2003), p. 172)

Invaded habitats include forests and forest gaps, fens, and riparian habitats. "[Frangula alnus] is a shrub that has become a serious invader of forested areas in northern America. It spreads rapidly and crowds out native woody and herbaceous plants by building dense stands. Seed production is high and seeds are dispersed by birds and small mammals. Seeds can remain viable in the soil for several years. Cut or otherwise damaged plants resprouts vigorously. ¶The shrub establishes in forest openings resulting from disturbances and logging and spreads from these sites into the adjacent vegetation (Burnham and Lee, 2010; Lee and Thompson, 2012). It is intolerant of heavy shade and is perhaps outcompeted by native trees in the long term as secondary succession proceeds (Cunard and Lee, 2009). Nevertheless, the shrub threatens natural plant communities with degradation including prairie fens of high conservation value (Fiedler and Landis, 2012). In forests, the plant forms a continuous shrub layer dominating the understorey (Fagan and Peart, 2004), reducing growth and survival of of juvenile canopy trees. This results in an altered relative abundance of native tree seedlings, favouring shade-tolerant species (Fagan and Peart, 2004). Sapling of native trees may have mortality rages of >90% under high density stands of buckthorn. This is likely to result in altered species composition of trees and in a delayed filling of canopy gaps (Fagan and Peart, 2004). ¶Glossy buckthorn invades deciduous broadleaved forests, mixed forests and pine forests. It also becomes abundant along water courses (Catling and Porebski, 1994)." (Invasive Plant Species of the World, 2nd ed., p. 192-193)

Propagation:  "It [Frangula alnus] is a prolific seed producer and seeds are dispersed by birds and small mammals. Seeds can remain viable in the soil for several years. Cut or otherwise damaged plants resprout vigorously." (Invasive Plants of the World (Weber, 2003), p. 172)

Native range:  Northern Africa, temperate Asia, and Europe (GRIN)

Native to Europe (except Mediterranean Isl.), northern Africa, and temperate Asia. (Invasive Plants of the World (Weber, 2003), p. 172)

Albania, Algeria, Armenia, Austria, Azerbaijan, Belarus, Belgium, Bulgaria, China, Czech Republic, Denmark, Estonia, Ex-Yugoslavia, Finland, France, Georgia, Germany, Greece, Hungary, Islamic Republic of Iran, Iraq, Ireland, Italy, Kazakhstan, Latvia, Lithuania, Republic of Moldova, Morocco, Netherlands, Norway, Poland, Portugal, Romania, Russian Federation, Spain, Sweden, Switzerland, Syrian Arab Republic, Tunisia, Turkey, Ukraine, United Kingdom (GISD)

Impacts and invaded habitats:  Invaded habitats: "Open forests and forest margins, riparian habitats." "Invasive in natural areas and not native to the area" in Canada, Alaska, and USA (except southeastern and western). (Invasive Plants of the World (Weber, 2003), p. 172)

Presence:

Pacific
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
Pacific Pacific	Pacific islands	not present	Island Biodiversity and Invasive Species (year unknown) no results were returned when searching Island Diversity and Invasive Species (IBIS) database for occurrences of Frangula alnus on islands

Also reported from
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
Canada Canada	Canada	introduced invasive	Global Invasive Species Database (2017) (p. 6) alien occurrences cited ONLY in US & Canada (20171208)
United States (continental except west coast) United States (other states)	United States (other states)	introduced invasive	Global Invasive Species Database (2017) (p. 6) alien occurrences cited ONLY in US & Canada (20171208); state occurrences do NOT include WA, OR, or CA

Comments:  Presence in Pacific Islands neither noted in Invasive Plants of the World (Weber, 2003), p. 172 nor in GRIN. Naturalized in the United States and Canada and cultivated (in unspecified places) per GRIN.

Control:  "Prescribed burning may kill seedlings but not necessarily larger plants. A foliar application of glyphosate during spring growth proved to be effective. Glyphosate can also be used to treat freshly cut stumps." (Invasive Plants of the World (Weber, 2003), p. 172)