Daniel Atha is an Associate Editor of NYBG‘s systemic botany journal, Brittonia, and a researcher specializing in floristics, taxonomy, and economic botany. He has taught classes in anatomy and systemics at the Garden’s School of Professional Horticulture and is currently working on a project to develop identifying DNA barcodes for plants of the Northeastern United States.

Nothing to Fear, but Fear Itself

Reynoutria japonica Houtt. (Japanese knotweed)

Godzilla-like, swaggering through our communities, Japanese knotweed is choking our waterways, breaking apart foundations, consuming whole houses and costing our cash-strapped economy millions of dollars per year in repair and mitigation. Ranked among the World’s 100 Worst Weeds, it is illegal to propagate the plant in England. It’s banned in Connecticut, Massachusetts, New Hampshire and Oregon and is considered a noxious weed in Alabama, California, Vermont and Washington.

What to do? Eat dessert! Yes, that’s right: dessert! Enjoy a beautiful lime-green parfait and do your part to halt Godzilla in her tracks (the plants are mostly females). Here’s how:

You’ll need about a dozen knotweed canes, harvested when they’re only about two feet tall–the thicker the better. Use a sharp knife and cut them off at the soil line. And don’t tell me you can’t find any! The plant occurs in 39 of the 50 states and is especially abundant on the east coast. No one will begrudge you for cutting them down. You can’t even mistake them for anything else. No other plant in North America grows six feet tall from thick, hollow, fleshy stems that are swollen at the nodes, has large, green oval- or heart-shaped leaves and produces numerous sprays of off-white flowers and small, winged fruits late in the season.

Wash the stems, remove the leaves and side branches, then peel the outer, fibrous rind from the stalks. If you start at the bottom (the thick end near the root) and peel toward what was the top of the plant, the rind will stop peeling just about where the stalk turns more fleshy and doesn’t need peeling anyway. Compost the rind and chop the peeled stalks into inch-long sections. If you wait too long into the season, the stalks become too fibrous and you have to use the tender side branches and top few inches of stalk, but these are harder to peel and take a little more time.

Now try a piece. They’re sour, right? Our grandmothers ate rhubarb (another sour plant, high in oxalic acid) and some of them loved it. And if you’re reading this, they survived! Now it’s your turn. Yesterday’s rhubarb is today’s knotweed. You can check off all the 21st-century must-haves: local (you can’t get more local than your own front yard), sustainable (just try to get them all), organic (depending on the site), conservation (clear habitat for natives), antioxidant (they contain resveritrol, the antioxidant in grapes), family-friendly (harvest them together), low-budget (as in free), home cooking (not found in restaurants–yet), etc., etc… Grandma was doing it all along, only without the labels.

But let’s get back to the recipe. Cover the chopped stalks with water and simmer until mushy, but they should still be bright green. Don’t worry if you cooked them too long, though. They’ll still taste just as good and still be an eye-catching green. Let the stalks cool and beat with a whisk, blender, or mixer. Strain the liquid through a cheese cloth to remove the fibers and return to a slow boil. While you wait, sprinkle one package of gelatin over one cup of cold water in a large mixing bowl and let stand one minute. Then pour three cups of the hot knotweed liquid over the gelatin and water, add three more packages of gelatin, one to two cups of raw cane sugar, and mix thoroughly. I think sugar works best with the tart stalks, but feel free to experiment with other sweeteners. You can try maple syrup for a purely local, seasonal dish. Chill in the refrigerator for about two hours or until just before it “gels.”

Spoon the thickened knotweed into parfait glasses and chill until firm. Top with yogurt, whipped cream or–better yet–wild berry preserves you and your family made on vacation last summer. For a little variety and fun, try layering the green with other bright colors like the pure white of yogurt, the purple of blueberry and/or the red of strawberry. Orange and green go well together, so try marmalade, too.

Just like rhubarb, to which it is related (and spinach, Swiss chard, black tea, cocoa and many other unrelated plants), Japanese knotweed contains oxalic acids. Aside from being a mild laxative for some individuals, the acid can interfere with calcium absorption in persons who are malnourished or otherwise have abnormal blood chemistry. But healthy persons have nothing to fear from consuming moderate amounts of knotweed, just as they might eat spinach.

So, if you can eat Swiss chard and chocolate, you can do your part to reduce the budget deficit, nurture biodiversity and promote family values–simply by having dessert!

Tags: edible weeds, knotweed

This entry was posted on Thursday, April 19th, 2012 at 4:30 pm and is filed under Around the Garden, Learning Experiences. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.