P&PDL Picture of the Week for
January 31, 2005

Buckthorn (Rhamnus cathartica and Frangula alnus)

Glenn Nice, Weed Diagnostician, Department of Botany & Plant Pathology, Purdue University

You have probably heard the name buckthorn before, primarily because of its association with the Asian soybean aphid.  Both these species, common buckthorn (R. cathartica) and glossy buckthorn (F. alnus), have been reported to be over-wintering hosts for the soybean aphid.

Both species are shrubs or small trees, growing up to 19 feet tall (Figure 1).  Both buckthorns produce several dark berry-like fruit (Figure 2 and 3).  Common buckthorns have spines at the ends of the stem (Figure 4) and have entire ecliptic-ovate to round leaves (Figure 5 and 6).  Glossy buckthorn’s leaves are more lanceolate being longer than wide.

Both of these species have been introduced to the US.  Common buckthorn is native to Eurasia and glossy to Eurasia and Northern Africa.  These buckthorns were brought into the US for the use as hedges or wildlife habitat.  Common buckthorn is considered a noxious weed in Iowa, Minnesota and Vermont, and an invasive weed in New Hampshire (http://plants.usda.gov).  In Indiana, common buckthorn has been reported in 15 counties and glossy has been reported in eight counties (Overlease, 2002).  In an assessment done by the Indiana Invasive Plant Species Assessment Work Group (IPSAWG) both common and glossy were rated high for their potential for expansion and difficulty of management.

The Purdue University Weed Ecology lab, headed by Dr. K. Gibson, is presently investigating the ecology of buckthorn in Indiana.  For more information please see the Weed Ecology Lab’s Researching Buckthorn web page.

Overlease, William and Edith Overlease.  2002.  100 Years of Change in the Distrabution of Common Indiana Weeds.  Unpublished.

Pictures courtesy of Purdue University Weed Ecology Lab

Click on image to enlarge

Figure 1. Common buckthorn

Figure 2. Common buckthorn fruit

Figure 3. Common buckthorn undeveloped fruit

Figure 4.  Common buckthorn spine at the terminal point of a stem

Figure 5. Common buckthorn leaf

Figure 6. Common buckthorn leaves

Figure 7. Young common buckthorn seedlings

Purdue Plant & Pest Diagnostic Lab Purdue Cooperative Extension Service