Friday, February 18, 2011

Foraging 3: Consume the Dastardly Knotweed, before It consumes You!

What is a weed? A plant whose virtues have not yet been discovered. – Ralph Waldo Emerson

Good luck spraying knotweed with herbicide. The roots go down 9 feet deep.
Photo: Marj Joly, Flickr ccl
As I've said before, the best way to deal with invasive species is to eat them. We seem to stretch everything else we consume to the brink of extinction, so why not put our gums to good use.

About Japanese Knotweed
Photo: dankogreen, Flickr ccl
Japanese knotweed is a non-native invasive plant that was brought to North America from Japan in the 1800s as an ornamental. Knotweed has become a threat in the wild and causes serious problems by displacing native flora and causing diversity damage. 

Japanese Knotweed is an herbaceous perennial, meaning it dies back to ground level each year. It looks like bamboo but actually is a member of the buckwheat family. The plant spreads by an extensive and rapid growing rhizome, as well as from roots and even stems.

Japanese knotweed is a concentrated source of emodin, used as a nutritional supplement to regulate bowel motility. The roots of Japanese knotweed are used in traditional Chinese and Japanese herbal medicines as a natural laxative.

The stems are green with red or purple specks, hollow and look like bamboo. They can grow up to 6-9' (2-3m) tall, forming dense clumps. The leaves are green, shield or heart-shaped, with a flat base and are up to 5" (12cm) long. Small whitish flowers appear on the tips from August to October but produce no viable seeds. The roots consist of rhizomes, which are yellow when cut, but can spread to a depth of 9' (3m) and radius of 23' (7m).

Photo: wayneandwax, Flickr ccl
Japanese knotweed is valued by some beekeepers as a nectar source. The young spring shoots are edible as a vegetable in both sweet and savoury dishes. When cooked its taste is similar to mild rhubarb. In Asian countries, Knotweed is dried and made into tea.

For the three following recipes, harvest Japanese Knotweed stalks at the “wild rhubarb” stage. In Nova Scotia that is late April through May. As it grows constantly until killed by frost, theoretically you could harvest the whole season.

The important thing is to get new growth. Stalks should be no more than 18-24" (46-60cm) long and at least 3/4" (2cm) in diameter.

Cut at ground level, lop off the top cluster of leaves and bring the stalks home. Once you’ve got them home, peel off the very outer layer (which is stringy). The stalks are hollow, so don’t peel too deeply or you won't have anything left to cook.  

Peeled knotweed. Photo: wayneandwax, Flickr ccl
You can eat the peeled stalks raw if you want (they are tart, juicy, and crunchy with a flavour somewhat like a Granny Smith apple), or chop up for use in just about any recipe calling for rhubarb. 

Each recipe has a link to the original source.

Applesauce-Knotweed Cake
3 eggs
1 1/4 cups granulated sugar
1/4 teaspoon salt
2 cups all-purpose flour
1 teaspoon baking soda
2 teaspoons cinnamon
1/4 teaspoon allspice
1/4 teaspoon nutmeg
1 cup plain applesauce
4 firmly-packed cups peeled stalk pieces (about 1/2" long)
1/2 cup chopped walnuts
powdered sugar

Photo: Terry Hope Romero, Flickr ccl
Preheat oven to 350ºF.  Grease a 13” by 9” baking pan. 

Beat eggs, sugar, salt and vanilla in a large mixing bowl until blended.  In the meantime, mix the flour, baking soda and spices together in a separate bowl.  

Add the flour mixture to the mixing bowl, then add the applesauce, knotweed pieces and walnuts and mix until blended. Pour the batter into the greased baking pan and spread evenly.

Bake at 350ºF for one hour, then remove from the oven and cool on a wire drying rack.  Dust the top with powdered sugar.  Serve warm or cold.  Makes 15 good-sized servings. 

Go Anywhere Knotweed Squares
Photo: rcakewalk, Flickr ccl
For bottom crust:
1 cup flour
1/3 cup confectioners sugar
1/3 cup butter (cold)

For filling:
2 eggs, lightly beaten
1 cup sugar
1/4 cup flour
1 teaspoon vanilla extract
1 teaspoon ground cinnamon
1/2 teaspoon allspice
1/2 teaspoon grated nutmeg
3 firmly-packed cups peeled stalk pieces (about 1" long)

Preheat oven to 350ºF.  Grease an 11” x7” x2” baking pan.  

Put crust ingredients into a food processor and pulverize until mixture resembles coarse crumbs.  Press into the bottom of the baking pan and bake at 350ºF for 12 minutes. 

To make the filling, place all the ingredients except the Knotweed into a bowl and mix together; then stir in the Knotweed pieces. Pour filling mixture over the warm crust and spread evenly.  

Bake at 350ºF for 35-40 minutes or until a toothpick stuck into it comes out clean. Cool on a wire rack. Cut into brownie-sized pieces and serve warm. 

Strawberry-Knotweed Pie
Photo: wayneandwax, Flickr ccl
You can substitute rhubarb for knotweed, but use the knotweed if you can find it—you’ll be richly rewarded.

3 to 4 cups strawberries, washed, stemmed, and halved
3 cups Japanese knotweed, peeled and chopped into 1/2-inch pieces
1 to 1-1/2 cups sugar (depending on the sweetness of your strawberries), plus extra for sprinkling over crust
3 tablespoons cornstarch
Pastry for a double-crust pie
3 tablespoons butter
1 egg yolk, beaten with 1 tablespoon water

Preheat oven to 375°F. In a medium bowl, toss together strawberries, knotweed, sugar, and cornstarch. 

Prepare pastry for the bottom of the pie; arrange in pie plate. Pour filling into shell and dot with butter. Slice remaining pastry into 3/4-inch strips and lay over pie in a lattice pattern. Brush crust with egg wash and sprinkle with sugar. 

Bake 45 to 55 minutes, until filling is soft and bubbling and crust is nicely browned (if necessary, cover pie edges with aluminum foil for the final 20 minutes to prevent over-browning). Serve warm with ice cream.


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