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Published In: Species Plantarum 1: 193. 1753. (1 May 1753) (Sp. Pl.) Name publication detailView in BotanicusView in Biodiversity Heritage Library
 

Project Name Data (Last Modified On 9/8/2017)
Acceptance : Accepted
Project Data     (Last Modified On 7/9/2009)
Status: Introduced

 

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2. Rhamnus cathartica L. (common buckthorn, European buckthorn)

Pl. 522 d, e; Map 2397

Plants shrubs or small trees, 2–8 m tall, dioecious, often incompletely so. Main stems 1 to several, the main branches ascending to loosely ascending and elongate, also with shorter, spreading to loosely ascending, relatively straight branches, these mostly thorn-tipped. Bark gray to reddish or purplish brown, sometimes with lighter blotches, relatively smooth, but with relatively prominent, raised lenticels in cross lines and branch scars, somewhat peeling on older, larger stems. Twigs relatively stout, slightly flattened, gray to yellowish brown, with small, dark lenticels, glabrous, the winter buds narrowly ovoid, with several overlapping scales, these reddish or purplish brown, glabrous except for marginal hairs. Leaves mostly opposite (occasionally subopposite on new growth, the petioles 9–28 mm long. Leaf blades 2–6(–9) cm long, mostly 1–2 times as long as wide, ovate to broadly elliptic or nearly circular, less commonly oblong-elliptic, mostly widest at or below the midpoint, angled at the base, tapered to a sharply pointed tip or the smaller leaves sometimes merely angled or rounded, the upper surface green to dark green, glabrous, slightly shiny, the undersurface light green, glabrous, the lateral veins mostly 2–4 pairs, these strongly arched toward the blade tip. Inflorescences axillary, small clusters of 2–9 staminate or pistillate flowers or occasionally reduced to solitary flowers, the clusters sessile, the individual flower stalks 2–6 mm long. Flowers imperfect. Sepals 4, 1.3–2.0 mm long. Petals 4, 1.0–1.3 mm long in staminate flowers, 0.6–0.9 mm long in pistillate flowers, lanceolate, entire at the tips. Style noticeably (3)4-branched toward the tip. Fruits 5–8 mm long, more or less globose or broadly oblong-obovoid, with 3 or 4 stones, black at maturity. 2n=24. April–June.

Introduced, scattered sporadically, mostly in the eastern half of the state (native of Europe, Asia; introduced widely in the northern U.S. south to Utah, Tennessee, and Virginia; Canada). Bottomland forests, mesic upland forests, banks of streams, and edges of upland prairies; also fencerows, cemeteries, and roadsides.

The R. cathartica complex comprises a group of closely related species of Eurasian buckthorns in Rhamnus subg. Rhamnus. The other two taxa reported as escapes in Missouri have commonly been misdetermined as R. cathartica by some collectors. The proliferation of these three morphologically similar species may be attributable to historical misdetermination of nursery stocks sold in this country. Although R. cathartica is still the most abundant member of the complex in Missouri and the one that has caused the most problems for land managers as an invasive exotic species, there is evidence that R. davurica is becoming more widespread in recent decades. Where members of this complex become established, they can spread aggressively by seed and eventually can form nearly impenetrable thickets. Seltzner and Eddy (2003) showed that the fruits and leaves of R. cathartica can have an allelopathic effect, that is, substances that leach from the fruits and leaves can inhibit the germination and growth of other plant species.

Steyermark (1963) noted that the dark green foliage of R. cathartica persists late into the autumn and that the bark, leaves, and fruits have a strong purgative effect when ingested. He further noted that a fruit extract was used historically in the preparation of a stain for maps and a pigment used by artists known as sap green. Although the species was not then considered to be a big problem in native midwestern ecosystems, Steyermark (1963) discussed that: “It seeds easily and sometimes becomes too plentiful in some areas.”)

 


 

 
 
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