Flowering Japanese Knotweed Traditional Cache

Flowering Japanese Knotweed, maybe of a different kind than the most common one? I was excited by the different flowers. It took a while to realize it must be a variety of Japanese Knotweed. Private, with permission granted.

Flowering Japanese Knotweed

Japanese Knotweed is an aggressive semi-woody perennial plant that is native to eastern Asia. In the 1800’s it was introduced to North America as an ornamental species and also planted for erosion control. It has since spread throughout the United States and Canada.

Japanese Knotweed is often mistaken for bamboo; however it is easily distinguished by its broad leaves and its ability to survive Ontario winters. Japanese Knotweed is especially persistent due to its vigorous root system, which can spread nearly 10 metres from the parent stem and grow through concrete and asphalt. This invader is very persistent and once it becomes established, is incredibly difficult to control.

Distribution and Habitat

Japanese knotweed occurs across the U.S. and has been reported to be invasive in natural areas throughout the northeast into Georgia and west to Missouri, with additional infestations in Oregon and Washington. It can tolerate a wide variety of challenging conditions, including deep shade, high salinity, high heat, and drought. Knotweed is commonly found near water sources, such as along streams and rivers, and in a variety of low-lying areas like ditches, waste places, utility rights-of-way and around old home sites.

Ecological Threat

It spreads quickly to form dense thickets and pushes out native plant species. Knotweed poses a significant threat to riparian areas where it can survive flooding events and rapidly colonize scoured shores and islands. Once established, populations are extremely persistent.

Impacts of Japanese Knotweed

Spreads quickly, creating dense thickets that degrade wildlife habitats.

Reduces plant biodiversity by competing with other native vegetation. Thick layers of decomposing stems and leaves on the ground make it difficult for native plant species to establish.

Aggressive plant with a strong root system that has been known to break through asphalt and concrete.

Plant populations are extremely persistent. Plants are able to survive severe floods and recolonize areas.

It can establish along riverbanks, where pieces of roots can break off and float downstream to start new populations.

Prevention and Control

Japanese knotweed is an extremely difficult plant to control due to its ability to re-grow from vegetative pieces and from seeds. Mechanical and chemical methods are most commonly used to eliminate it. Single young plants can be pulled by hand when soil is moist and roots are small. Roots and runners must be removed to prevent re-sprouting. Glyphosate and triclopyr herbicides have been used effectively, applied to freshly cut stems or foliage . Although a biological control agent has been found and is being released in the United Kingdom in 2010, there are no agents available for release in the U.S. at this time.

The cache is a tied in, camoed "micro" pill bottle, the push hard to open and close kind. Please BYOP and put back as you found it, with the rubber band around the log and the plastic bag sealed. I had to move the cache from the more promising hide because of thorns, so watch out for those. It's not there.

This part of the old RR grade is now private, with posted signs further on. I met the owner, had a nice chat and he gave permission for the cache.