A Prostrate Weed

Knotweed growing from a crack in the concrete

I used to be a tenant in a Brooklyn apartment with a concrete patio in the back (in fact I still am, but I’m describing a different place). I spent a lot of time back there grilling, talking with my friends, or just pacing around. Sometimes my roommates and I threw parties and we had huge groups of people over: naturally the largest groups of guests were usually packed on the patio. One day I was on the patio, quietly appreciating the garden plants, when I noticed that there was a crack in the concrete right next to the barbecue grill. Growing in this unfavorable environment was a flattened-out dark green plant.  It was spidery and sprawling with tiny leaves and wiry stems, but it was thriving right where everyone walked on it constantly.  In fact it was next to the grill!  I think I probably spent the whole summer standing on it and cooking without even noticing.

This plant was Polygonum arenastrum, more commonly called the common knotweed.  It has a prosaic name and it is not exactly a giant redwood in terms of magnificence, but perhaps the giant redwoods should look up to it.  Although it was originally from Europe, it is now on all of the continents except for Antarctica, and it can be easily found in most temperate locations.  It has made a living being underfoot.  A summer annual, the knotweed is a bicot with a long taproot. A member of the buckwheat family and a cousin to the smartweeds, it grows on footpaths, dirt roads, and in barnyards–anywhere it can find packed ground.  The foot traffic which is inimical to other plants is actually helpful to it.  The tiny plant has a great many common names.  To quote Edwin Rollin Spencer’s folk-lore treatise, All About Weeds, ”Like most of the weeds that came from the Old World this one has many English names: Ninety-knot, Centinode, Ninejoints, Allseed, Bird’s Tongue, Swynell grass, Swine’s grass, Redrobin, Armstrong, Cow-grass, Hog-weed and Pig rush.”  Spencer further underscored this point by calling the plant “knotgrass” throughout his little essay.

Most of the literature I have found concerning the knotweed/knotgrass is about how one can eradicate it (to summarize this accumulated body of wisdom: pull it up), however the lowly weed has found its way into some lofty places.  In A Midsummer Night’s Dream, the Athenian nobleman Lysander tells off his lover Hermia (when, thanks to the magical power of fairy herbs and plot contrivances, he has conceived a dislike for her):

Get you gone, you dwarf;
You minimus, of hindering knot-grass made;
You bead, you acorn.

This is an allusion to the folk belief that eating knotweed would retard a person’s growth. It was also reckoned by herbalists to be a astringent, coagulant, diuretic and expectorant, but I am not going to make any attempt to assess whether those things are true–I’m only reporting lore.  Small birds certainly enjoy the seeds as do some larger animals (hence some of the common names).  The Vietnamese make use of a closely related species Polygonum aviculare as rau đắng, an ingredient in hotpot.

A diagram of Polygonum aviculare which...um...happens to be in Italian

If you are feeling a bit trampled down you might pause to think of the knotweed.  It lives underfoot, but it lives everywhere.  Because of its humble appearance and lowly aspect (not to mention our haughty human tastes and perspectives) we call it a weed.  Looked at from a more expansive vantage (or maybe from the knotweed’s own perspective), we might call it a winner.

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