2012 NORTHEASTERN NATURALIST 19(4):601–610 Rhamnus cathartica: Notes on its Early History in North America Jessica Kurylo1,* and Anton G. Endress1,2 Abstract - Rhamnus cathartica (Common Buckthorn) is a well-established invasive species in North America. We searched early records of the species to help refine this species’ history in North America. This note presents strong evidence of Common Buckthorn’s entry to North America prior to the 19th century and suggests it was originally imported for medicinal, not ornamental, purposes. We then briefly discuss aspects of its expansion across North America to about the mid-19th century, when it was promoted as a hedge-forming plant. Such information is useful for reconstructing Common Buckthorn’s invasion history (including reasons for its success), as well as for understanding human-invasive species interactions in general. Introduction The history of human-mediated plant introductions into North America extends beyond 400 years (Viola and Margolis 1991). While the histories and intended uses—be it medicinal, fruit bearing, or ornamental—for some of the earliest introductions are unknown (Sturtevant 1972), there was generally a shift from importing plants for their utility (medicinal and fruit bearing) to importing for their ornamental desirability, as is reflected in the seed and nursery catalogs of the late 18th and early 19th century (Mack and Lonsdale 2001, Rehder 1936). Knowing the history of introduced plants can help further the understanding of plant invasions in general. For example, Mack (2003) describes gaining insights as to why some species naturalized very quickly while other, perhaps related species, take much longer. Similarly, he asks whether species naturalized long ago facilitate current species naturalization/invasions, a question relevant to the idea of “invasion meltdown” (Simberloff and von Holle 1999). One could also gain insight to explain why certain species are problems in some regions but not others. Our focus is to help clarify the early history of Rhamnus cathartica L. (Common Buckthorn) in North America up to about the mid-19th century. This time period was chosen as it coincides with the species’ increased promotion for use as a hedge plant. Tracking of the species from the mid-19th century to its decline in use is beyond the scope of this note. We aim not only to inform certain aspects of Common Buckthorn research, but also to remind readers that too often histories are taken as “common knowledge” without any authentication, 1Illinois Natural History Survey, Prairie Research Institute, University of Illinois at Urbana-Champaign, 1816 South Oak Street, Champaign, IL 61820. 2Department of Natural Resources and Environmental Sciences, University of Illinois at Urbana- Champaign, 1102 South Goodwin Avenue, Urbana, IL 61801. *Corresponding author - kurylo@illinois.edu. 602 Northeastern Naturalist Vol. 19, No. 4 attention, or reference to original sources; we also aim to encourage more historical literature reviews of this kind. This paper is the result of many years of searching historical archives as they have been digitized and increasingly made more available. For example, regional magazines such as Prairie Farmer and Northwestern Cultivator from the Midwest and New York Farmer and New England Farmer from the Northeast were searched. Historical floras and herbals as well as other various texts were referenced. Because newly digitized documents come available regularly and some non-circulating historical books are housed hundreds of miles away, ours was not an exhaustive search. We did not consult historical herbarium records for every state in the species range due to time constraints. Nor did we have the opportunity to explore ships’ manifests or nursery and seed-trade catalogues. Invasion History Common Buckthorn is native to Europe and western Asia (Godwin 1943), with large geographical ranges in both its native and naturalized ranges (Kurylo et al. 2007). This dioecious shrub or small tree (Godwin 1943) can live at least to 39 years (J. Kurylo, pers. observ.). The species has small honey-scented flowers pollinated by insects, with resulting green drupes ripening to black in September and October (Godwin 1943). Many species of both native and introduced birds are known to consume the fruits and are considered primary dispersers (Gourley 1985, Knight et al. 2007). Today, Common Buckthorn is highly invasive in certain regions of North America (Ontario, Canada, and the midwestern states of Wisconsin, Illinois, and Minnesota), and problematic from Colorado in the western United States to Nova Scotia in eastern Canada (Kurylo et al. 2007). It can form dense thickets across a variety of habitats, moisture gradients, and light levels (Knight et al. 2007, Kurylo et al. 2007). The taxon is readily associated with disturbance and disturbed habitats (Gavier-Pizarro et al. 2010; J. Kurylo, unpubl. data; Moffatt and McLachlan 2004). Common Buckthorn has undesirable effects in both natural landscapes (such as alteration of the local ecosystem’s biogeochemical cycle and increased predation of nesting song birds) (Knight et al. 2007) and agriculture settings (as an alternate host of Puccinea coronate Corda [Oat Crown Rust] and Aphis glycines Matsumura [Soybean Aphid]) (Heimpel et al. 2010). When was Common Buckthorn brought to North America? A review of the literature shows a general consensus of Common Buckthorn arriving in North America during the 19th century. The disparity arises as to which part of the century it arrived: early (Gourley 1985, Heimpel et al. 2010), the mid- 1800s (Seltzner and Eddy 2003), late (Gassmann et al. 2008, Heneghan et al. 2007), or just sometime during the nineteenth century (Mascaro and Schnitzer 2007). Luken and Thieret (1997) suggest entry was during “colonial times”, which would appear to be the most accurate. 2012 J. Kurylo and A.G. Endress 603 By the early 19th century, Common Buckthorn was “common in hedges” in the Philadelphia, PA area (Coxe 1806) and was so common in some parts of New England that it was considered indigenous to New York in early plant catalogues (Eaton 1817, Green 1814). An observation from Foster, RI noted the species was exotic, but appears naturalized in some areas (Drown 1825). Torrey (1824) questioned the indigenous designation because older New York residents noted the taxon in gardens before it appeared in woodlands. His doubts were supported by an earlier article listing Common Buckthorn as one of many naturalized species wrongly considered native (Rafinesque Schmaltz 1811). Given that Common Buckthorn takes between 9 and 20 years (Gourley 1985) to reach reproductive maturity, and the common perception over a large geographical area in the early 1820s of it being native or least naturalized, indicate an introduction before the turn of the 19th century. Why was it brought to North America? Common buckthorn is often said or implied to have been imported to North America as an ornamental, hedge, and/or shelterbelt species (Barnes and Wagner 2004, Brown and Brown 1972, Culley and Stewart 2010, Heimpel et al. 2010, Heneghan et al. 2007, Hough 1921, Maw 1981, Newhall 1893, Randall and Marinelli 1996). These designations are related but not interchangeable: ornamental is for decoration, a hedge is a row of shrubs or low growing trees, and a shelterbelt is a type of hedge used to protect an area from wind or soil erosion. It is also important to note that Possessky et al. (2000) is an incorrect citation for Common Buckthorn (Knight and Reich 2005, Knight et al. 2007, Madritch and Lindroth 2009), as that work concerned its close relative Frangula alnus Miller, syn. Rhamnus frangula L. (Glossy Buckthorn). Common Buckthorn was found in hedges in the United Kingdom, but there is no indication that it was specifically cultivated to form hedges (Godwin 1943, Hulme 1914, Miller 1754). While its common use as a hedge plant in North America in the mid- to late 19th century is well documented in monthly and weekly magazines from the time (e.g., The Canada Farmer [Toronto, ON], The Cultivator [Albany, NY], Maine Farmer [Augusta, ME]), the species is known to have been here before such use. Therefore, its use as a hedge plant in North America may have been the intent of its introduction to new areas within North America, but its initial introduction to the continent may have been for a different purpose. The first reported Common Buckthorn hedge was in Salem, MA, where it was established using young individuals dug from beneath a Common Buckthorn “tree” in a local physician’s garden (Derby 1834). Apparently this local physician had “the oldest plant of this species known in this country” and “long used the fruit as a cathartic in his medical practice” (Anonymous 1847a). Common Buckthorn is dioecious; therefore, there had to be other individuals nearby in order for viable seed to be produced. This usage suggests the possibility that Common Buckthorn made its way to North America initially as a medicinal plant before its more common use as a hedge plant. 604 Northeastern Naturalist Vol. 19, No. 4 Gourley (1985) states medicine is likely the oldest use of Common Buckthorn, but ends the discussion with its use in hedges. Thus, she does not equivocally state why the species was imported other than to say it has many uses. Gil-ad and Reznicek (1997) secondarily suggest the taxon may have been brought to North America for its medical properties after first mentioning its use as an ornamental species. Common Buckthorn’s specific epithet alludes to its medicinal properties as a cathartic. Purging Buckthorn is another, older common name for the species (Coxe 1806, Green 1814, Miller 1754). It has a long history in pharmacopeia (Hulme 1914) and would appear to be one of the “Buck-Thornes” mentioned in an English herbal dating to 1633 (Gerard 1633). Newhall (1893) states the taxon was often commented on by 16th-century medical writers. King’s American Dispensatory calls it a powerful cathartic, listing the effects (“brisk, watery purging, with nausea, dryness of throat, thirst, and gripes” [acute abdominal pain]) of consuming ripe berries, and suggesting it should be dispensed in a syrup form to lessen the severity of those effects. That entry goes on to mention the syrup at one time had a good reputation as a hydragogue (a purgative that causes watery diarrhea) in the treatment of gout, rheumatism, and dropsy (Felter and Lloyd 1900). Common Buckthorn was much earlier listed in The American Dispensatory from 1806 with a warning that “in the markets, the fruit of some other trees, as the black berry-bearing alder, and the dogberry tree, have of late been mixed with, or substituted for, those of buckthorn” (Coxe 1806). The entry indicates that Common Buckthorn juice was sold in apothecaries, and while it is no better than other cathartics, its effects “are more offensive, and operate more severely” (Coxe 1806). The taxon fell out of regular use by late 19th century (Newhall 1893). While Common Buckthorn is often mentioned as a medicinal plant in old texts, there is also mention of its use for making dye/tint in some of the same texts. Ripe berries produce a green dye/tint and unripe berries produce a “faire yellow colour” (Gerard 1633). Painters would mix juice from ripe berries with alum to produce a pigment known as sap green (Gerard 1633, Hulme 1914). There is a more in-depth discussion of Common Buckthorn’s many uses as a dye plant in Shishkin and Bobrov (1949). So Common Buckthorn could have made its way to North America as a plant of economic value for use in pigments, but the strongest evidence for its introduction appears to be related to its medicinal value, a use which is also reflected in the species’ name. Use as a hedge By the early to mid-19th century, live fences or hedges were in use but continued to be experimented with in the US, from the Northeast to the Midwest, for economic (expense of wooden fencing) and practical (availability of wood or stone for fencing in some regions) reasons (Downing 1835, Procter 1824, Warder 1858). Several native and non-native species such as Crataegus spp. (Hawthorn), Gleditsia triacanthos L. (Acacia, currently Honey Locust), Maclura aurantiaca Nutt. (syn. Maclura pomifera (Raf.) C.K. Schneid) (Osage Orange), and Arborvitae 2012 J. Kurylo and A.G. Endress 605 (probably Thuja occidentalis L.) were used and tested with much discussion in the weekly/monthly agricultural magazines (e.g., Maine Farmer, Michigan Farmer, Ohio Cultivator) as to the best species to use, the worst, and the how-to’s of hedge construction (Anonymous 1847c, Downing 1835, Nash 1847, Saul 1846, Warder 1858). Common Buckthorn was mentioned as a “superior” hedge species in an 1824 issue of New England Farmer, brought to light after a visit to area farms by the Essex Agricultural Society in Essex County, MA (Proctor 1824). The hedge that the Essex Agricultural Society visited was established in 1809 in Salem, MA by E. Hersy Derby. He had been unsuccessful in using other species (“English Hawthorn” and “Three-Thorned Acacia”) for hedge, but found Common Buckthorn “so hardy a plant, and so well adapted to hedges” (Derby 1834). Its praises were further sung by others since “its bark and leaf are offensive to insects, and the borer, the aphis, and others … remarkable for its hardiness, its robustness, and its power of adapting itself to any soil … one of the easiest plants to propagate” (Anonymous 1847b). Derby was so confident in this taxon as a hedge plant that within a few years of establishing his hedge he “furnished and distributed into different sections of the United States, plants sufficient to extend several miles” (Derby 1836). Movement west, north, and in-between The date and location of the first Common Buckthorn introduction or movement into the midwestern United States from the New England/Mid-Atlantic area cannot be stated for certain. The taxon could have found its way to the Midwest via Mr. Derby, but it could also have come earlier with settlers. Further investigation into more local historical documents such as settlers’ or country doctors’ diaries and small, localized publications from various regions may hold a more definitive date or more narrowed range. The Wisconsin Farmer recommended its cultivation as a hedge plant because of its temperature hardiness and adaptability in New England (Anonymous 1849). An earlier issue offered a testimonial about a very effective 10-year-old buckthorn hedge in Rockford, IL (Haskell 1849). Therefore, the species was in the Midwest by at least 1839. Anonymous (1847c) noted the existence of established hedges in the Chicago area, and describes the species growing wild along the Fox River, west of Chicago, IL, suggesting the species was in the Midwest even earlier. In Canada, Common Buckthorn was available for purchase as a hedge plant at Toronto Nurseries in 1864 (Leslie 1864). Northeast from Toronto along Lake Ontario, the taxon was included on a list of species present on “cultivated grounds” in the St. Lawrence and Great Lakes Valley, near Castleton and in the vicinity of Belleville, ON (Macoun and Gibson 1877). Common Buckthorn may have been in Canada before 1864 since it was promoted as a hedge plant starting about 1831 in the Rochester, NY area (Derby 1831), which is across Lake Ontario from Belleville and Castleton. In the 1930s, the taxon was introduced to western Canada (Saskatchewan) as a potential shelterbelt species, but quickly abandoned 606 Northeastern Naturalist Vol. 19, No. 4 (Archibold et al. 1997). It seems reasonable that the taxon’s introduction into Canada could very well have been as a hedge plant. Frugivorous birds and fruit/seed-eating animals have undoubtedly contributed to the spread of Common Buckthorn from homesteads to native ecosystems. The spread of a related species, Glossy Buckthorn, across Ohio coincided with the spread of Sturnus vulgaris L. (European Starling) across the same state (Howell and Blackwell 1977). Direct links between Common Buckthorn and a species or group of species contributing to its spread across a large geographic area such as a state or region have not been found, however. Wildlife has certainly played its part (see discussion in Knight et al. 2007), but Common Buckthorn seed was being sold by the pound, and it was widely promoted from the northeastern to midwestern United States as a hedge plant (e.g., Prairie Farmer [Chicago, IL], Genesse Farmer [Rochester, NY], New England Farmer [Boston, MA]); therefore, humans were no doubt critical dispersal agents (especially early in its spread) across the continent. Identifying the direction and speed with which non-native species spread from their point of introduction is instrumental in uncovering clues about their dispersal, identifying attributes of those habitats/sites most at risk, and clarifying why or how a species is differentially invasive across its range. For example, Silander and Klepeis (1999) constructed a historical distribution pattern for Berberis thunbergii DC (Japanese Barberry) through seed and nursery catalogs, personal accounts, herbarium specimens, old floras, and historic photographs. A pattern of distribution emanating from Boston, MA and New York City, NY was discovered. The human factor was also evident, as the taxon naturalized in popular vacation spots for those cities’ residents. A similar systematic review constructing a timeline of Common Buckthorn’s invasion history does not exist, but would be informative. Similar to Japanese Barberry, the taxon was actively cultivated, which can make tracking dispersal or “lag time” calculation (Crooks 2005) more challenging than for a naturally dispersing taxa moving out from a single entry point. The invasion will not be linear at a large scale, but would likely appear as several regionally and locally disjunct nodes that eventually coalesce. Such a map would illustrate important information. For example, if Common Buckthorn had been introduced into a state repeatedly, but never escaped beyond being adventive or persistent at the point of introduction, then there is something to be learned from that either in terms of soil nutrient needs or climatic tolerances. Similarly, this map would inform how long the species took to escape. Is there a difference in how long it took to proliferate after escape in one state versus another? These are just a few of the unanswered questions, but the answers would not only be informative for this species, but for invasive species ecology in general. Conclusion This historic account of Common Buckthorn has relevance for understanding its historical rates of spread and understanding the effects on propagule pressure 2012 J. Kurylo and A.G. Endress 607 on this species’ human-mediated success. The fact that Common Buckthorn was intentionally shipped across the continent helps explain why it had such an extensive range so soon after its arrival in North America. This human-mediated expansion would confound the calculation and understanding of a “lag time” between arrival, naturalization, and subsequent increase to problem levels across much of Common Buckthorn’s invaded range, but would nonetheless be an informative exercise. Acknowledgments We would like to thank Greg Spyreas for his review of this manuscript and Kathleen Knight and J. 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