The biology of Canadian weeds. 114. Symphyotrichum pilosum (Willd.) Nesom (Aster pilosus Willd.)

Abstract

Chmielewski, J. G. and Semple, J. C. 2001. The biology of Canadian weeds. 114. Symphyotrichum pilosum (Willd.) Nesom (Aster pilosus Willd.). Can. J. Plant Sci. 81: 851-865. Symphyotrichum pilosum (Willd.) Nesom, the white heath aster, is a robust, native North American, polyploid, herbaceous perennial. Until recently the species was treated as part of Aster. Its placement in the segregate genus Symphyotrichum follows the revised generic combinations proposed for North American asters. Occurring throughout eastern North America from Nova Scotia and Maine in the northeast, southward to Georgia, westward through southern Quebec and Ontario to Wisconsin, Iowa, Kansas, and Arkansas in disturbed areas such as fallow land, roadsides, dumps, quarries, arable fields, railroad beds, and embankments, the species is troublesome in the United States but a weed of minor importance in Canada. Two varieties, var. pilosum and var. pringlei are recognized. The former, the hairy variety, is weedier than the latter, the hairless variety. The species commonly occurs in fields following the first year of abandonment and may dominate in the second, or subsequent years. Control may be achieved through the application of selected herbicides. Also, even a moderate amount of grazing by herbivores such as small rodents and rabbits is sufficient to restrict growth in the species. Mildew is chronic and widespread in natural populations but typically neither kills the plants nor prevents seed production. This contribution summarizes the known biological data for the species. On lui connaît deux variétés, pilosum et pringlei. La première, la variété pileuse, est plus adventice que la variété glabre. L'aster éricoïde se rencontre couramment dans les champs l'année suivant leur abandon et peut y régner en maître l'année suivante ou les années subséquentes. On en vient à bout au moyen de certains herbicides. Une paissance modérée par des herbivores comme les petits rongeurs et les lapins suffit parfois à entraver la prolifération de l'espèce. Les peuplements naturels sont souvent attaqués par le mildiou, mais cette maladie, même si elle est répandue, ne tue pas la plante et n'empêche pas la production de semences.Mots clés : Symphyotrichum pilosum, Aster pilosus, aster éricoïde, biologie des mauvaises herbes, var. pilosum, var. pringlei 1. Name Symphyotrichum pilosum (Willd.) Nesom (basionym: Aster pilosus Willd.) -the white heath aster (Mulligan 1992), heath aster, frost aster, hairy aster, common old field aster, old field aster, steelweed [these common names typically refer to var. pilosum as opposed to var. pringlei (A. Gray) Nesom, Pringle's aster]; Asteraceae (Compositae), aster (composite) family, Composées (Fernald 1950;Anonymous 1990;Semple et al. 1996).

A comparison of two North-American asters invading in central Europe

“…Aster lanceolatus produced on average more new rhizome rosettes and longer and thinner rhizomes than Aster novi-belgii (tested in another experiment; Jedlicˇka, unpublished). These characteristics seem to be advantageous for Aster lanceolatus in soils with a loose texture, which was reported for native populations (Chmielewski and Semple, 2001). On the other hand, the vegetative spread of asters was very much reduced in compact soil (Schmid and Bazzaz, 1990).…”

Spatially Varying Relationships between Alien Plant Distributions and Environmental Factors in South Korea

“…Previous studies reported that wind is the primary dispersal force for these species [ 17 , 18 ], owing to the morphological features of their seeds, such as the bristled pappi and lightweight achenes (less than 1 mg). This is similar to other Asteraceae plants [ 17 , 18 , 21 ].…”

“…Both species are designated as harmful invasive plants by the Ministry of the Environment of the Republic of Korea because of their negative impacts on ecosystem diversity. They are also considered troublesome weeds in several regions such as the United States, Europe, and Australia [ 17 , 18 ]. It is important to estimate the critical environmental factors that facilitate the spread and establishment of harmful alien plants.…”

The biology of Canadian weeds. 113. Symphyotrichum lanceolatum (Willd.) Nesom [Aster lanceolatus Willd.] and S. lateriflorum (L.) Löve & Löve [Aster lateriflorus (L.) Britt.]

“…Although the species does reproduce vegetatively, large clones, such as those produced by S. lanceolatum are not typical. Rather, population structure is more similar to that of S. pilosum (Chmielewski and Semple 2001) in which less clumped, smaller, more individualistic clones occur.…”