Tasty Invasives

This is the first post by new RCR writer Costa. He's a local food advocate, gardener, and wild foods enthusiast living in St. John's. Area residents may remember edible hikes he has hosted in the past and very successful container and square foot gardening workshops. Keep an eye out for more wild foods highlights written by Costa in the future!

Japanese Knotweed

It grows in almost any soil condition, creating privacy screens in the blink of an eye.  Its roots can reach 7 metres out and 3 metres deep, taking over entire gardens in one season.  It can grow through foundations and asphalt, and destroy native ecosystems.  Some countries and states have enacted laws against growing this menace, and some have even classified it as controlled waste.  The only redeeming characteristic of this plant: it is edible!

Japanese knotweed (Fallopia japonica), on the World Conservation Union’s list of the world’s worst 100 invasive alien species, is native to Asia.  This plant was brought to Europe and North America as an ornamental plant and for fodder.

Its massive root system and ability to sprout from just a thumb sized piece of root or stem, have made this a common problem plant in St. John’s and other parts of Newfoundland.  Also called fleeceflower (for its sprays of white flowers in September) pieces of roots are easily transported in fill and soil..  Even though it dies back to the ground in the winter, its tall stems that resemble bamboo can grow up to 4 meters tall in one season.

In St. John’s, you’ll find Japanese knotweed (and its close relative Giant Knotweed, Fallopia sachalinensis) growing almost anywhere: in abandoned lots, along river banks, on the sides of roads and trails, and possibly in your own back yard.  It is common in the down town area.

Nearly impossible to dig up or cut down, this gardener’s worst nightmare is in the Polygonaceae Family (Buckwheat family), which also includes other wild edible stars, such as the docks and sorrels.  To bring this pest under control, some places like in Pennsylvania take a “if you can’t beat it, eat it” approach and hold festivals in the spring.

The young, thumb sized shoots are just starting to poke through the ground.  The shoots resemble asparagus, in looks and taste.  Some say Japanese knotweed tastes more like rhubarb, which is also in the Polygonaceae family.  Either way, use Japanese knotweed as you would asparagus or rhubarb: chopped into bite sized pieces and thrown into stir fries, soups, or omelets; or mix with apples or berries and throw them into pies, cobblers, or jams.  It has a stronger flavour than rhubarb, and is more tart, so you may need to use less knotweed and more of the other fruits in your recipes.

Young shoots can easily be harvested by snapping or cutting off at ground level when they are several inches tall.  Plants will send multiple shoots up throughout the spring and early summer and is one of the earliest plants available to foragers.  The best part is that unlike most other wild edibles, this is one plant that is impossible to kill by over harvesting!

Be careful about eating too much though…Japanese knotweed is high in emodin, a laxative (but for some, this is a benefit).  Knotweed also contains oxalic acids which can be a concern to people prone to kidney stones and gout.  If your doctor has warned against eating too much spinach or chard because of these conditions, then you should also limit your knotweed consumption.  For the rest of us though, knotweed can safely be part of a healthy, diverse diet.  In fact, Japanese knotweed contains resveratrol, a compound famously found in grape skins and wine which is being investigated for anti-cancer and anti-inflammatory properties.  It is also high in vitamins A and C, and potassium. For recipes using Japanese knotweed, check out this site.

Like all wild edibles, before you harvest, make sure you know the area is safe.  Has it been sprayed with chemicals?  Is there lead in the soil?  While the scientific articles I have read indicate knotweed does accumulate lead in its roots, there are different conclusions about lead accumulation in the shoots.

So, to play it safe, I won’t touch the knotweed in my down town back yard and will visit one of the many other places that this delicious menace has invaded.