Saturday, July 28, 2012

History of the Introduction of Mile-a-minute weed (vine) - Persicaria perfoliata

Early warning that went unnotcied; for more on the story see: Edouards Baltars - Collection of Mile-a-minute in Maryland Aug. 23, 1964

History of the Introduction of Mile-a-minute weed (vine) - Persicaria perfoliata

Extract from my report to the US Forest Service: full document includes and annotated bibliography email request for full pdf at ipetrus"at"

               Persicaria perfoliata (L.) Gross, Mile-a-minute weed or vine, is an annual vine indigenous to Asia that infests nurseries, orchards, openings in forested areas, roadsides, and drainage ditches in the eastern United States (Yun Wu, R. C. Reardon and Ding, 2002). The introduction and establishment of Persicaria perfoliata in eastern North America, and the corresponding potential to cause economic or environmental harm was reported in Rhodora, the Journal of the New England Botanical Club. In the summer of 1946, a specimen from an ornamental nursery in Stewartstown, York County, Pennsylvania, was sent to Dr. John M. Fogg[1] at the University of Pennsylvania Herbarium.[2]  The new species was first detected around 1936 in the germination of holly seeds sent from Japan. The unknown species was identified at the time as Polygonum perfoliatum (L)  (and checked against specimens in the collections of the National Academy of Sciences in Philadelphia and the Gray Herbarium at Harvard University (Moul, 1948)
Mile-a-minute on the run: 
Leslie J. Mehrhoff, University of Connecticut, 
               The establishment of Persicaria perfoliata in the Chesapeake watershed was an unintended outcome of the hybridization program  that produced some of the most reliable rhododendron hybrids for the United States. Although  Persicaria perfoliata was collected as early as 1890 as Polygonum perfoliatum on ballast (Suksdorf 1607) by Wilhelm Nikolaus Suksdorf  (1867-1935), a botanist living in Bingen, Washington, the species failed to establish (J. C. Hickman and C. S. Hickman, 1977). Persicaria perfoliata was also collected in 1954 under the name Polygonum perfoliatum 2.5 miles north and 1 mile east of Pitt Meadows, British Columbia, Canada, by D. Faris Jr. (Faris 261)  There are no further herbaria records for Persicaria perfoliata in British Columbia, Canada, suggesting that either the species failed to establish or that is being misidentified (Hill, Springer and Forer, 1981).

Table 1 Persicaria perfoliata Details for: V47875 - 1954 collection BC, Canada UBC[3]

Accession No.
Scientific Name
Polygonum perfoliatum
British Columbia
2.5 miles north and 1 mile east of Pitt Meadows
Grid Reference
Patches growing over sprayed Canada Thistle by road.
1954 Sep 8
D. Faris Jr.
Collection No.
Determined by
C.F. 1954
To 2 m long- light green foliage. Maturing- bright blue covering over dark blue. Division of Botany, Science Service Department of agriculture, Ottawa, Canada.
Previous Identifications

                 In 1926 Joseph Benson Gable (1886 - 1972) started an ornamental nursery on the family farm and orchard land where he was born.  Starting out at first with native evergreens, trees and shrubs, he eventually turned his attention to hybridizing some 2000 cultivated varieties of hardy rhododendrons and azaleas suitable to the climatic gardening conditions of Mid-Atlantic (Weingartner, 1973).[4] Gable planted his seedlings and hybrids among the woodlands on his land, a form of horticultural intercropping that helped him "select" the most adaptable specimens suitable to real-life landscape conditions.[5]   

               Gable was attracted to the ornamental potential of Persicaria perfoliata's blue berries and allowed the plant to grow and reproduce in his "woodland" nursery the following year.  The novel introduction quickly established a monoculture between the rows of trees in the family orchard as well as along the paths and lanes of the nursery "choking all other herbaceous plants". Dr. Edwin T. Moul, a noted phycologist and Professor of Botany at Rutgers University, was shown around the nursery in October 1946 by Mr. Jack Swartley.[6]  Moul noted the vigor of Persicaria perfoliata was such that it overwhelmed and killed even Lonicera japonica Thunb. as well as Sambucus canadensis L. and various Rubus species. Moul also pointed out that Persicaria perfoliata was able to cause defoliation of apple trees in the orchard.  Mr. Gable reportedly used 2-4D in an futile, ineffective attempt to control the now spreading, aggressive weed. Japanese beetles, Popillia japonica, did more damage than the chemical control (2-4D). However he also noted that the Persicaria perfoliata (P. perfoliatum) recovered quickly after the beetles abundance and infestation peaked in mid-summer (Moul, 1948).  

mile-a-minute weed -fruit-  Persicaria perfoliata (L.) H. Gross:
Leslie J. Mehrhoff, University of Connecticut,
               In 1936, P. perfoliata (reported as Polygonum perfoliatum) germinated in a research seed project at the USDA Plant Industry Station in Beltsville, Prince George's County, Maryland.[7] According to Dr. Joseph Ewan, USDA Glenn Dale Research Station, the Persicaria perfoliata germinated in seed received from Nanjing, Jinagsu Province, China. In the seed of a species Meliosa sent for C. W. Cowgill's research which did not germinate Persicaria perfoliata seedlings grew and subsequently were eradicated (Moul, 1948). It is possible the species designated as  Meliosa was a misspelling of Meliosma a genus that was under investigation and grown from seed at the research facility in the mid to late 1930s (Erlanson, 1949). By the 1950s, Persicaria perfoliata was seen as a possibly "troublesome weed" that was becoming established in Pennsylvania nurseries (Gray, 1950)

               Eduards Baltars, a University of Riga, Latvia, trained botanist who came to the United States in 1949, collected several specimens of P. perfoliatum which he sent to the Smithsonian National Museum of Natural History (1959) and the University of Maryland Norton Brown Herbaria (1964; see Table 8). Eduards Baltars took over the curation of the Clyburn herbarium in Baltimore and continued to collect native species of Maryland flora until he died in 1972.[8]  P. perfoliata was reported in Maryland and by 1982 was established and spreading throughout central Maryland reaching the USGS Patuxent Wildlife Research Center along the mid-reaches of the Patuxent River in Maryland by 1989.[9] Persicaria perfoliata was found in North Carolina in 2010 continuing its spread along the east coast of the United States, as well as moving west into Ohio. (Bargeron and Moorhead, 2007; Poindexter, 2010;, 2011)

[1] Dr. John Milton Fogg, Jr., botanist, University of Pennsylvania professor, Dean, and Vice Provost, director of the Morris Arboretum, instructor at the Arboretum School of the Barnes Foundation, and director of the Barnes Foundation Arboretum: John Milton Fogg Papers, 1931-1982.  
[2] (Swartley 1946) (J. C. Hickman and C. S. Hickman, 1977)
[4] Weingartner, E. W. (1973). Gable Azaleas In The Olive W. Lee Memorial Garden. Journal American Rhododendron Society, 27(2). Retrieved from
"About 1,500 of the approximately 2,000 azaleas in the Lee garden are Gable hybrids and the oldest are now more than 30 years old. Maturity has revealed the ultimate characteristics of each variety. Thus the original 'Mary Dalton' is 15 feet high, although many of its branches are pendant from the burden of its salmon-pink flowers over the years. 'Forest Fire' is not a large plant but is said to be the only existing hybrid with R. tschonoskii as a parent, and its sheets of blossoms are so densely packed that most are unable to open beyond the bud stage. There are a number of highly regarded but as yet unnamed seedlings in the garden. The most interesting of these is T-4-G, a very dwarf, dense, dome-shaped plant covered with double salmon-pink flowers. 'Stewartstonian' is probably the purest red of any azalea, and that feature has been exploited by a mass planting of some 125 specimens, now mature, on a slope back lighted by the afternoon sun. Another area has been given over to 35 specimens of 'Mary Dalton' which at blooming time block the path they line under the weight of their flowers. After the original 'Mary Dalton,' probably the most admired specimen is a huge plant of 'Big Joe' which towers over and seems to shelter other varieties in the same color range. (One frequent visitor makes it a practice to curtsy as she passes 'Big Joe.')
        The introduction of Gable rhododendrons has probably not yet ended and Caroline Gable continues to screen the seedlings remaining in the famed Gable woods, exercising the same disciplined judgment which made the original Gable label assurance of the highest quality. In general the rhododendron plants in the Memorial Garden are not as old as the azaleas, but two Gable hybrids which are greatly admired are specimens of 'Cadis' and 'Caroline,' secured in 1952, some years before they were introduced. 'Cadis' is now 8 feet high and 11 feet wide and has carried as many as 535 trusses. "
[5] The Rhododendron Legacy of Joe Gable  by Donald W. Hyatt.  Hybrids and Hybridizers, Rhododendrons and Azaleas for Eastern North America, Livingston & West, Harrowood Press, 1978.
[6] The author presumes that this is the same Jack Swartley - Stewardstown, York, Pennsylvannia.October 9,1946    J. C. Swartley "in old orchard" Harvard Herbarium; see Table 8       reference #353583.
[7] Glenn Dale  Plant Research Station, Henry A Wallace, Beltsville Agricultural Research Center (USDA-ARS BARC)
[8]  Isaac Rehert. June 19, 1971. Walk With Plant Specialist Presents Variety of Lessons. Baltimore Sun
Eduards Baltars was unable to find work as a botanist, teacher or researcher. He therefore worked as a carpenter and donated his time and knowledge to the people of Maryland as a volunteer curating the herbarium and planting and maintaining the native plant section of the Clyburn Arboretum in Baltimore, Maryland.
[9] personal communication with the author:  Matthew C. Perry, Research Wildlife Biologist, USGS Patuxent Wildlife Research Center. email March 7, 2012
"I first identified mile a minute weed (Polygonum perfoliatum) at Patuxent on September 11, 1989 in the Gabrielson Lab drainage ditch."

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