Looking for Shrubs in All the Wrong Places — Finding a Rare Irish Plant that Became the Scourge of the Midwest

By Liam Heneghan

ClonburBuckthorn0001Every time I extricate a tick from near my groin I recall with fondness a trip I took with a small group of youthful botanists to the west coast of Ireland in 1984. I tagged along with third year undergraduates on the annual University College Dublin Botany Department’s field trip to the Burren in Co Clare. The trip was designed to help these naturalists hone their plant identification skills, since the Burren – a grassland on karst topography — has a truly exceptional flora. One finds botanical treasures there not readily found elsewhere. I was a third-year zoology major and at that time my passion was for chrysomelid beetles with their shimmering metallic elytra and chironomid flies, the males of which family have those marvelous antennae that perch like out-sized Christmas trees upon their heads. I mention here, merely as a grateful aside, that my mentor for beetle work was Jimmy O’Connor for Dublin’s “Dead Zoo” (National Museum of Ireland, Natural History) and for flies it was Declan Murray from UCD. I am indebted greatly to both these excellent men.

We crossed through the Midlands early in the month of June stopping off at the Bog of Allen, a fine though now of course greatly diminished raised bog, which generation after generation of Irish folks have burned as peat to heat their damp and somewhat chilly homes. And as we approached our destination we stopped several times at sites of scientific interest. As groups of hushed botanists whisperingly conferred over the relative hairiness of sepals, the flexuousness of petals, the lanceoloation of leaves and so forth, I swept the margins of small steams with my net with giddy abandon. The art of sticking one’s head into a net of agitated insects to retrieve one’s prizes, and to transfer them to a small vial of ethanol, has not received its due attention, but we shall have to reserve that meditation for another time. Once back on the mini-bus I’d stow the net under the bus seat and we’d be off to the next venue.

As we approached Co Clare a mild clamor emerged from the botanists, upon whose finely pubescent legs — need I point to the genderlessness of this observation? — ticks were now promenading. By the time my net was recognized as the tick delivery mechanism, the little blighters has already made their greedy ascent to the humid and agreeable habitat of the nether-regions that seem to be their preference. The ticks were painstakingly removed that evening, a process, the self-administration of which I can admit to having a certain fondness. The trick here is patience, a steady hand, and the graduated amplification of pulling force. Ticks relent.

Now, a point I want to make here is metaphorically a rather small one. Ticks, not always noticed when in the field become a nuisance when they are in the wrong place at the wrong time. I had inadvertently transported these ticks from their point of immediate origin, and their impact was uncomfortably felt in a manner that demanded attention. These ticks that so afflicted my botanists were not, of course, themselves invasive species, nevertheless they can serve to illustrate the rudiments of invasive species biology. Invasive species are those spread by human agency outside their typical range and have an impact in the host location significant enough to warrant management action. Setting aside, for now, the terminological skirmishes over distinctions between non-natives, exotics, invasives and so on, I simply ask you to bear in mind as important the factors of transportation between locations and an impact in a new range that is assessed as consequential.

My botanists forgave me, for botanists are generally an affable and forgiving race, and we settled down to the real task of our trip, botanizing. On that trip I encountered out on the limestone of the Burren a plant that I barely registered at that time but that was later to assume a dominant role in my life. This was Rhamnus cathartica, or buckthorn as it is commonly known. Buckthorn is a shrub or smaller tree with alternate finely tooted leaves and spiny twigs. It is to my eyes a fairly pretty plant. When I saw this relatively rare Irish plant again fourteen years later it was as, arguably, the commonest woody species in the Chicago Wilderness region. Introduced from its native range across the Old World where its populations are generally small it has become, after a lag-time of several decades, explosively successful in the US Midwest. From a conservation management perspective buckthorn is “public enemy number one” since it encroaches upon, and in many instances dominates, open land set aside for conservation purposes. Much of my research work and that of students I have worked with in subsequent years has been devoted to this plant.

In the summer of 2012 I traveled back to Ireland to find buckthorn growing natively. My younger son Oisín (then 16) traveled with me. The trip was more arduous than we expected. With time ticking away we discovered that although several Irish botanists could tell us roughly where to locate the plant, none could say where a population of buckthorn was to be found with the precision required by a man with little time to spare.


Buckthorn prefers rocky lake shores and is generally found on soils developed on calcareous bedrock. It is found across Europe sporadically and in parts of North Africa and western Asia. My D A Webb’s An Irish Flora reported that it was to be found in Ireland in “rocky places and lake-shores and other seasonally flooded habitats; occasionally in the west and centre, very rare elsewhere.” I did not have a clear recollection of where exactly in the Burren we had visited in the 1980s, and having reason to visit some other of the Irish National Parks, we first explored the Muckross Peninsula in Killarney National Park in the South West. Daniel Kelly from Trinity College, Dublin, an expert of the vegetation of the National Park, informed me that the shrub is present but quite scarce in the Killarney limestone area. My son and I followed the Arthur Young trail in the park that winds across the limestone, close to Reenadinna Yew Woods (about which I have written elsewhere), and out onto the rocky beaches adjacent to the lake. I left Oisín by the lake shore skipping limestone pebbles as I scrambled over rocks by the water looking for buckthorn. Several hours later, we abandoned the effort.

We walked dolefully back to the visitor center. Oisín was somewhat less morose it can be said. I suggested that we detour to see Muckross Abbey, a deserted monastic settlement, to whet our appetites with the sauce of viewing the graves of long-dead monks. Along the way we listened in on the jarveys, drivers of jaunting cars who ferry visitors less inclined to peripatetic excursions around the park. “When the horse goes up the hill he goes slow”, a jarvey sagely informed a client, “…but when he goes down the hill he goes very slow!” At the center of the monastery is an ancient yew tree and one can sit at the cloister’s edge and admire this old tree. Children ran about us and mothers fretted as their darlings darted towards the paneless windows some distance above the flagstones. The monastic roof was long gone and jays called raucously from among the graves. As we walked away from the abbey out of the corner of my eye I saw a shrub that seemed happily to fit the habit of buckthorn, and there is was! Worth the morning's walk, a gift of departed monks.

The leaves were quite lanceolate (tapering and longer than broad), unusual for buckthorn, and I reflected a little on the morphological deviation of our Chicago populations from the native condition. Perhaps there had been some inter-species hybridizing in the New World that invigorated the introduced population. In Ireland the plant was growing singly at the edge of a trail and not clumped in distribution as we find it around Chicago, where sometimes in fact it grows as a impenetrable monoculture. Photographs were taken, and leaves were pressed between the pages of my Webb’s Irish Flora. We would come back the following day to look at the other vegetation around Muckross Abbey.

Later that evening we ate at the home of old friends of mine, Bill Quirke and Helena Twomey. Both are excellent naturalists and have worked in the Killarney area since the 1980s. In 1982 Bill had introduced me the national park’s own problematic invasive shrub Rhododendron ponticum which proliferates throughout the oak woodlands. R. ponticum is native to southern Europe and southwest Asia. No doubt there is a Bulgarian ecologist visiting home nostalgically looking for populations of this shrub in its native land. As naturalists do we drank tea and lolled about with vegetation samples and every botanical volume in the house opened to the Rhamnaceae. Helena held up my prize. “Oh nice…”, she said, “you found spindle!” I had found Euonymus europaeus, a handsome shrub by any measure, but not buckthorn. Spindle is also associated with limestone and is found occasionally in Ireland. On another occasion I might have been pleased. The night was not a loss of course; Oisín provided a rather fine dramatic reading from the “American Girl” story collection for the entertainment of the Quirke-Twomey daughters, and for our collective amusement he juggled deftly. Nevertheless, we left Killarney a couple of days later without seeing our plant.


Finding Rhamnus cathartica in Ireland was important to me for a number of reasons. I wanted to observe buckthorn in a location where its discovery was a cause for satisfaction not concern. There is a habit among conservationists to demonize less desirable species no matter how lovely they may be. Perhaps this it’s inevitable to so regard the enemy. When I worked on Rhododendron removal in Irish woodlands in the 1980s I quite happily attributed to this, after all quite blameless species quasi-imperialistic motives and entered into battle with it. Novice conservation volunteers the world over are oftentimes taken aback when they show up to “restore” a site and are forthwith kitted with loppers and bow-saw and sent about their deadly task. We called the removal “Rhodo bashing”, and when incredulous tourists would yell at us as we hacked away at the beautifully blossomed plant I would feel sorry for their ignorance, though some of the ignorance was ours. Though what we were doing was, I still think, correct from a conservation perspective, the ethical theory upon which it is based is far from transparent.

So when I moved to Chicago I felt inclined to like buckthorn even though local restorationists regarded at times with the enmity I once had for Rhodo. It was, after all, an Irish native successfully setting down roots in a foreign land. So successful that I claimed that my research on it was motivated by jealousy! But just as Hitchcock’s The Birds made ominous organisms that individually we love well enough, a leafy flock of buckthorn is an abomination. Returning this past summer to find it in Ireland where it was ecologically well-behaved, a rarity among its fellows, was in some ways an attempt to vindicate my high regard for it.

There was another reason besides. When I traveled with my botanists on that first tick-infested trip I was setting out to be a naturalist. I wanted to both identify, and identify with, organisms. Insects were my thing back then, but I hoped to become a good botanist as well. Though they are professionally closely related an ecologist and a naturalist are not quite the same thing and I became the former and not so much the latter. Ecologists, as a rough and ready rule with exceptions, concern themselves with processes whereas naturalists concern themselves with “things” – organisms. Ecosystem ecologists — process ecologists in an aggravated way — squint at the world and rather than seeing “things” they see the buzzing connections between “things”. The buzz is typically the buzz of death: predation, decay, necrophagy. I have primarily been a student of death and decay, and have learned less about the lives of individual organisms than I had hoped. A methodological distinction between ecology and natural history, again I write in approximations, is that ecologists tend to be more experimentally inclined, setting up “event traps” in which processes are allowed to occur, whereas the naturalist’s primary methodology, walking, sends her into the trap that nature pleasantly sets. A naturalist is a sentient body in motion. Traveling in Ireland to find buckthorn called for a natural historian’s skill and rehabilitating this field skill, seemingly lost in me, was as much as anything, my motivation.

Yet with time moving along rapidly I was yet to find a single buckthorn individual.


I next visited Connemara National Park, in the far west coast of Ireland. Tim Robinson, whose three volume account of Connemara’s social and natural history is definitive, wrote and told me that I would not find buckthorn there. He would, he said, see the plant out on the Aran islands when he was working there but it was not to be found in the metamorphic and granitic parts of Connemara that I was visiting. My last hope was to find it in east Co Galway. Jim White, my old teacher from University College Dublin, had provided me with information from D A Webb and Mary Scannell’s Flora of Connemara and the Burren which confirmed east Galway locations. White warned though that whereas general locations of the plant were known, it might be hard to find specific sites where one was guaranteed to find it.

As it happened Oisín and I were traveling on this leg of the journey with my cousin Brendan Heneghan. Brendan, a lawyer, is a man of vast and eclectic interests and he took a friendly concern in my locating buckthorn. On the last day of our travels together we decided that we would drive through East Galway and on up into Co Mayo. Our ultimate destination that day was a graveyard in which several generations of dead Heneghans have been laid to rest so I did not want to tax the patience of my amiable cousin. After all, the search area for buckthorn was reasonably large. Webb and Scannell reported that it is frequent near Oughterard, a town north of Galway City and locally abundant by the south shore of Lough Mask. Coincidentally, I had run into Declan Little of Woodlands of Ireland, an old friend from my graduate school days, in Glendalough, Co Wicklow, who had suggested that I try Clonbur woods for buckthorn. OisinPartry

Since Clonbur Woods was on our route we stopped and walked through the woods towards the lake. The woods are close to Cong, where John Ford’s The Quiet Man was filmed. There had been some recent cutting of plantation trees in the woods; the site looked disheveled and unpromising. Flies buzzed about us aggressively. Brendan sprinted: for a bookish man he can gather up quite some speed. We moved further into the woods towards Lough Mask. The flies vociferated in their buzzing way and Brendan attempted to make himself the less appetizing target by sprinting randomly. He merely provoked their further interest and they feasted on that fine legal head. Calculating that his patience was good for about another thirty minutes, we pressed on, each with our personal head-cloud of flies. Was it to be that my first love, insects, would keep me from locating my newer botanical love? And in the way that such things happen, even to those of us who believe not at all in fate or the gods we walked around a bend in the the trail and there, stretched out across a little limestone terrace, was the loveliest little population of buckthorn.

Later that day, three living Heneghan crouched down in a graveyard near Partry, Co Mayo surrounded by a virtual monoculture of dead Heneghans.

Many thanks to all the Irish botanists that helped me find buckthorn. In addition to the ones named in the piece I recieved useful information from Drs Gerry Clabby and Noel Kirby.

Follow me on Twitter @DublinSoil for 140 character updates on my columns. Links to previous 3QD columns here. Pictures are of Buckthorn leaves on copy of Webb's An Irish Flora and Oisin Heneghan with dead ancestral Heneghans in Co Mayo.