The Physical  Removal of a Recent Population of Phytolacca americana (Pokeweed) in the Niagara River Gorge
P. M. Eckel
Res Botanica
Missouri Botanical Garden

http://www.mobot.org/plantscience/ResBot/niag/
January 22, 2012

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The Physical  Removal of a Recent Population of Phytolacca americana (Pokeweed) in the Niagara River Gorge

 

by Patricia M. Eckel

Missouri Botanical Garden

 

 

The Physical  Removal of a Recent Population of Phytolacca americana (Pokeweed) in the Niagara River Gorge

 

P. M. Eckel

Missouri Botanical Garden

St. Louis, Missouri

January 22, 2012

 

VIDEOS:

Digging out Pokeweed roots

Area of the removal

Array of roots removed

A large root

 

 

 

Master Naturalist Program, Cornell University,

New York State, Volunteer Contributions

 

Volunteer hours to produce this article:

Transportation, 16 hours to and from Saint Louis and Niagara Falls, 4 hours in town, 20 hours total. Research and analysis before and after work: 16 hours; computer preparation, herbarium label and specimen preparation: 8 hours. On site: 4 hours.. Total = 48 hours.

 

 

Introduction

 

The Niagara River and its environment has a long history of tributes to the uniqueness  and the scientific and public value of its botanical resources. The islands residing in the Niagara River between the two cataracts, the American and Canadian, or British Falls, were set aside (as The Niagara Reservation) in 1885, and, contemporaneously, the Queen Victoria Niagara Falls Park in Canada, the crest of the River at and around the cataracts above and below them. The value of these resources was attested to by the distinguished American and British botanists Asa Gray, of Harvard University, and Joseph Dalton Hooker, Director of the Kew Royal Botanic Gardens. The political justification to the New York State legislature for the creation of the Reservation was articulated by Frederick Law Olmsted. The Niagara Reservation was established by the State of New York and was and is the first continuously operating State Park in the United States, arguably the origin for State and Provincial Parks systems throughout the United States and adjacent Canada and the foundation for subsequent parks and preserves throughout the State of New York.

 

The nationally and internationally recognized biological resources of the Niagara River environment have been severely compromised throughout the years since the establishment of the Niagara Reservation, leaving challenges for the stewardship and custodianship of these areas on both sides of the River. One of the most serious challenges is the control of noxious species and the absence of functional policy commitment and resource allocation for this control by the governments involved in the Niagara River area.

 

It was while hiking along the gorge of the Niagara River in 2011 that a station of what the author knew to be an invasive species was observed. It was a Mother Site, that is, a location in a relatively pristine natural area with a species population with a main individual at its center and descendent individuals radiating outward from it from oldest in the center, to youngest on the periphery. Numerous Mother Sites for different invasive species can be identified all along the Niagara River gorge and adjacent environment on both sides of the River.

 

The species was Phytolacca americana L. (Pokeweed). This species, like Aster pilosus, is native to western New York and, unlike A. pilosus, has a long history of occurrence in the Niagara River gorge and vicinity, including Goat Island, being found there on August 1, 1862 by George W. Clinton - a time when its rich purple fruits would be evident. Since then it has been found around Lake Erie, in the Queenston area, Niagara Glen, Lewiston, LaSalle and so on. Zenkert (1934) reported it as “Rather common” on the “edges of moist woods, in clearings, pastures, and along hillsides in various soils; sparse to rather abundant.” It is associated with disturbed soils. The large perennial, fleshy taproot is poisonous, according to Voss (1985), and the rest of the plant is variously edible if used with a knowledge of how to destroy the toxic elements, as the juice of the raw fruit is a powerful purgitive.

 

In the Niagara gorge flora, I have used the species as an indicator of disturbance, and also as an indicator of conditions conducive to the introduction and spread of other invasive species. Its presence is an indication that there is a threat to the native plant community. It is listed as an invasive and noxious weed by the USDA. According to the Ohio Perennial & Biennial Weed Guide (OPBWG) the plant is poisonous in all of its parts to humans, pets and livestock, and the roots are the most toxic.

 

 

General Methods

 

Site work took place on Saturday, November 26, beginning at 12:00 PM ending at 4:00 PM, or approximately four hours..

 

Activity took place in light, brightly overcast, unseasonably warm, but still cool conditions, suggesting an extended season of growth for the year 2011.

 

Tools used included secateurs, a heavy metal shovel, a heavy pitch-fork, a trowel to pull away loose soil from the roots, several large, durable plastic bags, smaller durable bags to collect and retain any fruit or seed material, a camera to record activity and results. Gloves were used at all times to prevent toxic plant juices from skin contact. Care was taken when drinking from water bottles to prevent inadvertent ingestion of toxic emetic, purgative plant juices.

 

 

 

Care must be taken with any chopping tool (such as a shovel) that the roots are not fragmented. Some web sites suggest that only the top crowns of the root need be removed, but others have reported new shoots arising from root fragments left behind in the soil. Every attempt was made to remove the entire below-ground structure.

 

Due to the significance and cultural importance of the biota of the site, invasive plant removal must be careful, as though one were removing material from an archeological site.

 

Bags and tools were kept close to the stems being extricated to avoid migration of plant parts.

 

For several days the area had been subjected to rather heavy seasonal rains. The Thursday and Friday (24th and 25th November) were clear. There was no precipitation on Saturday the 26th, nor the 27th. The soil at the site was thus saturated and rather loose, hence relatively easy to manipulate and to prevent root pieces from remaining and possibly regrowing.

 

In November, much of the fruit of Phytolacca americana had set and dropped into the surrounding soil. Although what fruit and their seeds existed were carefully collected in bags for later disposal, it was clear that, by November, much seed had already dropped down to the soil surface.

 

The stems of the plants are succulent, with chambered pith, and deciduous down to the ground. Many had been bleached of pigment (from their ordinary bright purple color) and were at first inconspicuous, and difficult to see as an apical portion of large underground roots. Several plants had only the main stem remaining, the branching upper parts with their fruit already rotted away. It is likely that after a few more weeks, the stems would have rotted quite down to the green buds at the apex of the thick underground root and the population would have been otherwise undetectable during the winter months.

 

 

Although a wet November is recommended as a good time to remove the large, carrot-like roots, the colorful deep purple fruit-clusters should have been removed earlier in the season at a time to be determined: in Chautauqua County in the southern tier of western New York, anthesis is stated as July 7 with fruit on August 2 (Eaton and Schrot 1987). The August date for collecting the seed for removal is reinforced by Farmer and Hall (1970), see also Steinbauer and Grigsby (1956).

 

The area is along a weedy approach from the top of the trail from the parking area below the Robert Moses Overpass just south of the Lower Arch Railroad Bridge off Whirlpool Street in the City of Niagara Falls, New York. The property is owned by the New York State Power Authority interrupted by the privately owned property associated with the Bridge. The area is close to the old Custom’s House facing the bridge. All associated areas are under active development. The old bolts from the Suspension Bridge, a structure that existed prior to the present Railroad Bridge, were evident in the boulders and rock faces.

 

The gorge and portions of the Robert Moses Parkway are maintained by the New York State Department of Parks, Recreation and Historic Preservation. The gorge trail system is being developed and maintained by the New York State Department of Parks, Recreation and Historic Preservation, the New York Power Authority and the Department of the Interior of the federal government.

 

The top of new trail down to base of gorge: the trail is covered by gravel over a manufactured kind of cloth that reduces erosion on the path, which is relatively steep. The path appears to have been prepared by a small bulldozer. The upper portion of the path leads down rather gradually along the top of the talus slope, along the base and face of the dolomite caprock, terminating before a man-made opening in the caprock that is faced with a metal door and lock. From the emanation of sewage odors it is presumed that this door is associated with a CSO (Combined Sewer Outlet) associated with drainage in the urban areas adjacent to the bridge and parkway.  A small area of seepage from the caprock was evident on the first leg of the descent that crossed the path, but which is probably not evident except after precipitation.

 

All path areas occur on natural talus rubble and soils except in the first leg from the gorge rim. A heap of transported soil is associated with the CSO which constitutes transported soil mixed with rubble (rubbish constituted of old bricks, old broken glass) and large angular talus cobbles mostly less than 12” on the longest side, coupled with black cinder covering all and exposed at the surface. It is assumed that this rubble was deposited some years ago to form a path down to the CSO, which displays signs of trampling in the weeds in front of the door indicating the door is in relatively frequent and recent use. The CSO door is located at the top of the talus slope and is associated with the dolomite caprock. A heap or deposit of transported soil at the CSO door together with the rubble indicates that the soil was accumulated in a weedy waste area and deposited at the site to form a path down to the CSO.

 

The approach on the first leg of the trail leading down to the CSO is dense with a weedy flora of non native species. Species noticed in November included: Alliaria officinalis (Garlic Mustard), Arctium minor (Burdock), Chrysanthemum parthenium (Feverfew), Dactylis glomerata (Orchard Grass), Daucus carota (Queen-Anne’s Lace), Hesperis matronalis (Dame’s Rocket), Nepeta cataria (Catnip), ), Poa interior (Interior Meadow-grass), Panicum capillare (Witch-grass), Rubus idaeus (European Red Raspberry), Solanum dulcamara (Bitter Nightshade), basal rosettes of Verbascum thapsus. Aster pilosus (Old Field Aster) may be considered to be native to the area. Since 1934, when it was not reported by Zenkert for the area in a fifty mile radius around a point in the City of Buffalo, it has increased its presence in the local Niagara flora as if it were an invasive species.

 

A large shrub of Ligustrum sp. (Privet) at least five years or more old grew at the cliff base, with no descendents observed. Also Rhamnus cathartica (Buckthorn). Rosa canina (Dog Rose), grew about the path, a shrub species in the gorge usually associated with plantation. The most common alien weed, becoming more frequent toward the CSO door was Leonurus cardiaca (Motherwort) in the Mint family (Lamiaceae-Labiatae).

 

The only species of plant considered rare in New York State at the site were populations of Pellaea glabella, which grew on a different substrate and were in no detectable way affected or disturbed by removal of the Pokeweed population.

 

From the CSO door the path makes a sharp right and plunges steeply downward to the buolder-field along the path at the base of the gorge. A steel cable is affixed to boulders to assist the hiker up and down the talus slope.

 

The Pokeweed area is directly in front of the CSO door. No plants of Pokeweed were found either on the approaches to or descent from the gorge rim. Examination of the rim or crest of the gorge directly above the Pokeweed-CSO site and beneath the overpass of the Robert Moses Expressway revealed a wooded vegetation remarkably clean of alien weeds (and garbage), comprised mostly of grasses and Solidago altissima, Solidago flexicaulis, with an Arctium minus plant and a liliaceous weed that may have been planted. Old patches of Vinca minor (Periwinkle) were present. Some Phragmites occurred due to a slight seepage amid the grasses.

 

The largest individual of the Pokeweed population was surrounded by ‘haloes’ of younger, smaller plants extending out from the central plant in front of the CSO door. Seven large Pokeweed plants were removed at the end of the path leading from the crest to the CSO door.

 

 

All native soils on the lower talus slopes seem relatively clean in comparison with the weedy path approach, and filled with native plant species, in November, mostly Solidago and Aster species, as on the gorge crest above, particularly, Solidago flexicaulis and S. altissima, Rhus toxicodendron (Poison Ivy), and some Polymnia canadensis (Small-flowered Leafcup), all typical of the talus slopes in this area, except for occasional stems of Verbena urticifolia (White Vervain), which was rather unexpected.

 

The only other species with bright berries present at the site were the red berries of Solanum dulcamara (Bitter Nightshade).

 

Before Pokeweed removal, the large plants formed a screen in front of the CSO door, concealing it, which may have been part of an intention to establish it there.

 

 

Results

 

A total of 57 roots and four seedling roots were removed during a period from 12:06 PM to 4:00 PM, or around four hours.

 

The area involved was approximately 20’X 5’ cleared, or 100 square feet.

 

If in three hours, a 100 sq.ft.’ area was cleared, then 33 sq. ft. per hour = 1/2 square foot per minute.

 

All above-ground parts and their associated below-ground parts were removed from the population of Pokeweed located in front of the CSO door.  Care was taken to remove the root tips in the below-grown root system. All fruits remaining on the stems were removed. All plant materials were bagged and removed from the site and disposed of in city trash containers. At the end of the day, there was no evidence that this population had existed at the site and all signs of disturbance had been removed.

 

No other species of plant was disturbed other than a few plants of the abundant Leonurus cardiaca (Motherwort) with which the Pokeweed was growing.

 

Examination of areas peripheral to the population, above it on the gorge crest and below it at the base of the gorge were examined for additional populations of Pokeweed, and none could be identified. The eradicated population seemed relatively new and quite mature, probably producing fruit for at least one season (and probably several) before the 2011 season. Several rather large stems that occurred with their fruiting tops gone were removed.

 

Seven additional medium-sized plants were removed on both sides of the path just up from the main population (total of ca. 14 stems).

 

 

Discussion

 

Due to the historical and cultural values associated with the biota of the site, the attitude to adopt when manipulating the biota of the site is curatorial (something akin to cleaning and clearing an archaeological site) to preserve the valuable elements of the plant community and the natural environment. It was also important to restore the site to a clean condition as it was and is being used by the public.

 

The Niagara gorge alone is a 14 - mile combined biological environment, with seven miles in Canada and seven in the United States. Within this patchwork and discontinuous environment are many areas needing custodial attention. The purpose of the removal of this one species, among so many needing removal, was to document the resources required to achieve success in this one site with one particular species. Any concept of plant community restoration at the Niagara lands would require an effort such as this one. Preservation can be achieved one site at a time, one species at a time.

 

Every invasive or otherwise noxious or inappropriate species, such as horticultural or patented species used in inappropriate landscaping activities, has its own properties. Some are easy to remove, some difficult, some relatively rapidly recolonize through seed set, underground rhizome development, cloning, etc. The removal of some species results in an extirpation of that species from the Niagara flora, in other species, the future expansion or restoration of the population is to be determined.

 

In the case of the Pokeweed plants, even though the single population had probably existed for several seasons, there seemed to be no observable evidence in November, 2011, that the species had expanded beyond the immediate and expanding periphery of the Mother plant, that is, birds, animals or simply gravity downslope had not contributed to dissemination of this species from the site.

 

The major investment of energy with Phytolacca americana appears to be in the development of its large root. The root is a simple structure and does not produce extensive secondary swellings or constrictions that remain behind in the soil, but the entire root mass may be excavated with perhaps no further regrowth.

 

 

That the climatic conditions were so mild for November at Niagara suggests a contribution to an extended season of growth of all green plants and a modification of cold temperatures as a limit on dispersal, competition and vigor between species and their populations, either weedy, alien and native alike.

 

The Pokeweed site was determined to be a Mother Site by the author, that is, the surrounding landscape was free of this particular species, the undisturbed landscape free of not only this species, but many others as well, as seen in the densely populated biologically ‘dirty’ soils used to prepare the path from the gorge rim to the CSO door.

 

Many other such sites may be seen in the environments along the Niagara River and its gorge in the public lands areas, such as one tree of Cotinus coggygria, Smoke-tree, a horticultural species, ringed by its descendents at Artpark, Rhamnus cathartica (Buckthorn) planted with Lilacs, Ligustrums and other horticultural aliens, Salix matsudana (Cork-screw Willow) planted on the spoil area overlooking Artpark and on the crest of the gorge by the Lewiston-Queenston Bridge, by the various lawn weeds creeping into DeVeaux State Parks through the backyards of residents neighboring the northern bountary of the park, especially Lapsana communis (Nipplewort) the vector of which can be seen from Lewiston Road stretching west through DeVeaux Park across Whirlpool State Park and down into the base of the gorge of the River.

 

The absence of Phytolacca americana (Pokeweed) from the mix of alien species along the disturbed path and path margins leading down to the CSO door seemed unusual.

 

The station before the CSO door may be examined for regrowth in the spring of 2012 (the year subsequent to the year of removal), but it is unlikely that additional plants will be found in the first spring, due to the complex and large nature of the rootstalk. The smallest stems observed occurred directly within the entrance-recess to the CSO door, and these had relatively large roots. It is likely that the plant is a biennial, with a shoot developing in the first year, and the stalk in the second, due to the development of a large, fleshy root. The search for seedlings in the spring may be undertaken, but it is likely that two years may be necessary to readily identify the plant, or else it would need a full summer’s growth to readily identify new seedlings - such as reexamination in November 2012. From images posted on the internet, seedlings show red stems, although, like the older plants, the leaves are green.

 

It is assumed that birds are the primary vector for longer distance dispersal than within a few feet of the mother plant. It is perhaps theoretically doubtful that this population would have contributed in any significant way to dispersal in the immediate area, a suggestion that might be easy to confirm or disprove in 2012 during the growing season.

 

For restraint on the expansion of populations of this species, it is recommended that all flowers and fruit be removed from the stems in August, taking especial care that the plant is not stimulated to produce new flower and fruit structures - presumably to remove these structures as late in the season as possible before fruit fall. Care must be provided that fruits are removed before an interest by birds is developed. Racemes on the plants removed did not seem foraged by birds, perhaps because there were so many other food options, and the population was small.

 

Roots are best removed after the soil is well moistened by heavy rain in fall (November) and spring (March or April). It is easier to remove these plants where the root plays a significant factor in the durability of the population when the soil is loose and saturated.

 

 

Conclusions

 

For removal of a species such as Phytolacca americana with a significant root system by a single individual, total removal of the root system was undertaken. There is probable good expectation that the population has been eradicated at the chosen site as stems were still above ground, juvenile as well as old plants were removed.

 

A total of 57 roots and four seedling roots were removed in all during a period from 12:06 PM to 4:00 PM, or around four hours.

 

The area involved was approximately 20’X 5’ cleared.

 

If over four hours, a 100 sq.ft.’ area was cleared = then 25 square feet per hour = 1/2 [0.42] square foot per minute.

 

If $7.25 is the minimum wage per hour, then the minimum cost to employ a laborer or contract worker to remove this population of Pokeweed would be $25.00.

 

Acknowledgements.

 

The author would like to thank Meg Janis for arranging permission to study the removal of Phytolacca americana from a site in the Niagara gorge, and Kimberley Smith for helpful discussions and arranging contacts within State Parks. Both individuals are employed by the New York State Department of Parks, Recreation and Historic Preservation.

 

Literature Cited

 

Eaton, Stephen W. and Edith Feuerstein Schrot. 1987. A Flora of the Vascular Plants of Cattaraugus County, New York. Bulletin of the Buffalo Society of Natural Sciences. Vol. 31. Buffalo, NY.

 

Farmer, Jr., R. E. and Geraldine C. Hall. 1970. Pokeweed seed germination: effect of environment, stratification, and chemical growth regulators. Ecology. Vol. 51(5) pp. 894-898.

 

Steinbauer, G. P. and B. Grigsby. 1956. Interaction of thermoperiod, light and substrate in the germination of seeds of pokeweed (Phytolacca americana L.). Plant Physiology (Suppl.) 31:36-37.

 

Voss, Edward G. Michigan Flora. 1985. Part II. Dicots (Saururaceae-  Cornaceae). Cranbrook Institute of Science Bulletin 59 and University of Michigan Herbarium, Ann Arbor.

 

Zenkert, Charles A. 1934. Flora of the Niagara Frontier Region. Bull. of the Buffalo Society of Natural Sciences. Vol.16. Buffalo, New York.