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<br />Common buckthorn - Invasive species: Minnesota DNR <br /> <br />Page 1 of2 <br /> <br />Common buckthorn Rhamnus cathartica) <br /> <br /> <br />Description: <br /> <br />Appearance: Tall understory shrub or small tree up to 20' high with a spreading <br />loosely branched crown, often multiple stems at the base. Brown bark with <br />elongate silvery corky projections (Caution: native plums or cherries have a <br />similar bark). Female and male plants. <br /> <br />Branches: Cut branch exposes yellow sapwood and orange heartwood. Twigs <br />often end in stout thorns. <br /> <br />Leaves: Alternate, sometimes opposite; broadly elliptic pointed at the tip, <br />smooth, dark glossy and small-toothed. leaves stay green late into fall. <br /> <br />Flowers: Inconspicuous, appear in Mayor June, clustered in the axils of leaves. <br /> <br />Fruit: Clusters of black 1/4 inch fruit ripen on female plants in August and <br />September. Seeds are viable for 2 - 3 years in the soil. <br /> <br />Roots: Extensive fibrous root system. <br /> <br />Ecological Threat: <br /> <br />. Aggressively Invades oak forests, savannas, prairies and riparian woods, <br />completely eliminating native plant diversity in the understory over time. It <br />thrives particularly on well-drained soils. <br />. Plants leaf out early and retain leaves late into the fall creating dense <br />shade. <br />. Seeds have laxative effect on birds who disperse them. <br />. Introduced to North America as ornamental shrubs. <br />. Common buckthorn Is on the MDA Restricted noxious weeds list in <br />Minnesota. <br /> <br />Control Methods: <br /> <br />Mechanical <br /> <br />hllp:ll\\ ww.dnr. state. mn. us/in vasi ves/terrestria I plants/woody Icommon buckthom.h tOll <br /> <br />5/29/2009 <br />