Royle (Himalayan balsam) is an invasive alien annual up to 3 m in height with showy flowers that are generally pink or purplish. Native to the Himalayan region, I. glandulifera was first recorded in Canada in 1901 in Ottawa, and is now found in eight Canadian provinces: British Columbia, Manitoba, Ontario, Quebec, Nova Scotia, New Brunswick, Prince Edward Island and Newfoundland. Impatiens glandulifera is typically found in riparian habitats and may spread rapidly because its seeds are readily transported via waterways. Up to 2500 seeds are produced per plant and dispersed explosively up to 5 m from the parent plant. This can result in dense monotypic stands which prevent establishment of native plants and make stream banks vulnerable to erosion when the shallow-rooted plants die back. Impatiens glandulifera is susceptible to glyphosate but because herbicide use in riparian areas is not advised, other control methods such as hand weeding, mowing or flaming have been used. Methods for eradication are most successful when upstream populations are controlled first, as the plants spread downstream. Removal of I. glandulifera should be managed synchronously with non-native control measures and ideally be accompanied by planting native species to ensure the restoration of native species composition. The prognosis for curbing its spread in Canada seems poor as it has quite rapidly become established along waterways in many regions, following a pattern seen over the past two centuries in Europe.Key words: Impatiens glandulifera, Impatiens roylei, Himalayan balsam, impatiente glanduleuse, policeman's helmet riparian, invasive plant, weed biology Clements, D. R., Feenstra, K. R., Jones, K. et Staniforth, R. 2008. La biologie des plantes exotiques envahissantes au Canada. 9. Impatiens glandulifera Royle. Can. J. Plant Sci. 88: 403Á417. Impatiens glandulifera Royle (impatiente glanduleuse) est une annuelle envahissante pouvant mesurer jusqu'a`trois me`tres de hauteur. Ses fleurs tre`s voyantes sont ge´ne´ralement roses ou mauves. Cette plante originaire de l'Himalaya a e´te´signale´e pour la premie`re fois a`Ottawa en 1901, mais on la retrouve ap re´sent dans huit provinces (Colombie-Britannique, Manitoba, Ontario, Que´bec, Nouvelle-É cosse, Nouveau-Brunswick, Iˆle-du-Prince-É douard et Terre-Neuve). Impatiens glandulifera affectionne habituellement les milieux riverains et se multiplie rapidement, car les cours d'eau en transportent aise´ment les graines. Chaque plant donnera jusqu'a`2500 semences qui seront disperse´es de manie`re explosive jusqu'a`5 me`tres de distance de la plante me`re. Il en de´coule parfois de denses peuplements monotypiques qui empeˆchent les plantes indige`nes de s'e´tablir et peuvent rendre les berges vulne´rables al 'e´rosion lorsque meurent ces plantes peu profonde´ment enracine´es. Impatiens glandulifera est sensible au glyphosate, mais l'usage d'herbicides e´tant de´conseille´dans les zones riveraines, on recourt a`d'autres me´thodes de lutte, notamment le de´sherbage manuel, la tonte ou le br...

Verbesina encelioides (Cav.) Benth. & Hook. f. ex A. Gray, golden crownbeard, is a sunflower-like herbaceous annual plant ranging in height from 0.3 to 1.7 m with showy yellow flowers. It is native to the southwestern United States, the Mexican Plateau, and other parts of tropical America. Its invasive characteristics include high seed production (as many as 300-350 seeds per flower and multiple flowers per plant), seed dormancy, ability to tolerate dry conditions, and possible allelopathic effects. Disturbed areas with a relatively sandy substrate within warm, arid climate zones are vulnerable to invasion by V. encelioides. Verbesina encelioides is found on all of the main Hawaiian islands except Ni'ihau but is particularly problematic on Midway and Kure Atoll, where it may threaten the habitat of nesting birds such as Laysan and black-footed albatrosses and Christmas and wedge-tailed shearwaters. Many other Pacific islands with similar habitats could be invaded by V. encelioides. The plant has become naturalized in many other U.S. states, parts of South America, the Bahamas, Cuba, the Dominican Republic, Puerto Rico, parts of Europe, Saudi