The biology of Canadian weeds. 135. Lonicera japonica Thunb.

Abstract

Japanese honeysuckle (Lonicera japonica Thunb.) is a twining semi-evergreen vine native to Japan, Korea and eastern China. Over the past 150 yr it has been introduced as an ornamental and become established in temperate and tropical regions worldwide. It was first discovered in Canada in 1976 in southwestern Ontario woodlands and has since been found growing without cultivation in 15 localities. While L. japonica does not occur very frequently in southern Ontario, climate change models suggest that it may become more abundant in this region. Its predominance elsewhere derives from morphological and physiological characteristics that allow it to be particularly successful in the edge habitats of fragmented landscapes. Through extensive vegetative propagation and competitive ability it occupies space which may otherwise host a diverse native flora. The plant has many uses in Asian medicine and is a popular ornamental, but has been prohibited in some regions due to its displacement of other species. A combination of cutting and foliar application of glyphosate has proven to be an effective control method in some circumstances. Planting of L. japonica should be discouraged and horticulturalists should consider alternative attractive vines. The spread of L. japonica should be monitored in Ontario and control of newly established populations should be considered to avoid costly large scale control in the future. Key words: Invasive species, Lonicera japonica, weed biology, climate change