Observations on Elide asparagoides and Polygala myrtifolia in Corse, France
Elide asparagoides (= Asparagus asparagoides, Liliaceae) is an ornamental species originating from South Africa. This plant is a geophyte producing climber stems up to 2.5 m long. The plant is known to be naturalized in Portugal (including Azores), Sicilia (Italy), South of France (including Corse). This plant is known to be very invasive in Australia. According to a field survey made in 2002, the plant is expanding in Corse. This study provided useful information on its biology and ecology. It is not sold by local horticulturists but is supposed to have escaped from gardens. E. asparagoides is heliophile, susceptible to drought and its seeds are thought to be propagated by birds. This plant has a long growing period (from October to April) and produces very rapidly a huge biomass and a lot of seeds. It has a wide ecological tolerance (it grows from 0 to 210 m of altitude). E. asparagoides could represent a threat to indigenous species having the same life cycle as Prasium majus (Lamiaceae) which is rare in Corse. Although the species is stopped by dense vegetations, its extension is favoured by transportation routes (roads, paths ...) and fires. This plant might cover large surfaces in the future and become very invasive. It should be monitored and contained.
Polygala myrtifolia (Polygalaceae) is an ornamental shrub originating from South Africa. The plant is present in Sicilia, Southern France and Corse where it is casual. It is considered invasive in Hawaii (USA). The study shows that the plant does not resist very well to summer drought, that it is heliophile and its seeds seem to be dispersed by wind. Even if the plant should be monitored, its susceptibility to winter low temperatures and to drought limits its populations and it is not considered invasive or potentially invasive.
Sources
Paradis G (2004) Observations sur les stations de l’espèce subspontanée Polygala myrtifolia L. à l’ouest d’Ajaccio (Corse). Bulletin de la Société Botanique du Centre-Ouest. 35, 91-102
Paradis G, Piazza C (2004) Précisions sur les stations d'Elide asparagoides (Asparagaceae) à l'île Rousse et Tiuccia (Corse Occidentale). Le Monde des Plantes. 482,1-2.
Paradis G (2002) Expansion à Ajaccio (Corse) de l’espèce introduite Elide asparagoides (L.) Kerguélen (Asparagaceae). Le Monde des Plantes. 476, 16-20.