Unwhackable Weeds

Three words sum it up: mare's tail again.

I've mentioned this plant before, but have yet to do it justice. "Again" is the right tag - though admittedly a bit like "dj vu all over again." This filigree weed comes again. And again. And again. And again....

"Whenever you see one, pull it up," advisers advise. My problem is that "whenever" is all the time. If you do pull it, its black roots stretch elastically (Alec is convinced there's an evil underground genie pulling back), and then it snaps, suddenly. All its roots need to do is grow again.

Joe Gallagher, expert Irish plot-holder, says in his least encouraging brogue: "Don't worry. You'll never get rid of it."

Red, gatepost-leaning while he and Joe chat, agrees. "See that one? You pull it up. Three of its pals come up to see where it's gone!"

"At least I'd like to slow it down," I sigh, having had another half hour at it, aware that tomorrow morning I'll find exactly the same number of hirsute green mare's tails gesturing at me defiantly.

"Slow it down is right," says Joe between his teeth. "That's all you'll do."

The gardeners' clich is that a weed is a plant in the wrong place. Emerson, even more generously, said "a weed is a plant whose virtues have not yet been discovered."

Well, Ralph Waldo, you were wrong about mare's tail (or "horsetail" as many call it). This weed's "virtues" are long known. It has old names like "pewterwort," "scouring rush," and "scrubby-grass."

A favorite book, "The Grasses, Sedges, and Ferns of Great Britain," by Anne Pratt (my copy has its first owner's 1871 inscription), includes the horsetails. (Though not ferns, they are similarly primitive, flowerless plants, producing spores, not seeds.)

The corn horsetail was, Pratt writes, "very serviceable in the kitchens of olden times "for cleaning wooden and pewter tableware. Silica crystals on its stems make it sandpapery. Also, according to Richard Mabey's fascinating "Flora Britannica" (1996), boiled horsetails make a fungicide that works on rose mildew.

Children find horsetails fun. The stems are jointed. Pulled apart, they can be rejoined. So horsetail has a 20th-century name: Lego plant.

I can even admit to its beauty; massed along forgotten ditches or canals, it looks like a soft green mist.

RED tells me that mare's tail was introduced to Britain from India to consolidate railway banks. Another gardener tells me the same story, only it's from South America, not India.

The truth of these claims I have yet to determine. Certainly its wiry roots could hold up any slidy bank. But Elizabethan writers mention it, and railways were rather rare in the 16th century.

Its virtues aside, mare's tail is still a notorious worldwide weed, deserving choice descriptive language. Anne Pratt puts it discreetly: "It sometimes runs all over the land, and is most difficult of extirpation."

My previous mention of mare's tail electrified a gardener-reader in Washington State. (I was at school with her husband, but that's another story.) She wrote: "Well, Bruce and I ... went outside immediately and picked an average sized horsetail. Our yard is covered....

"We actually believe now to have found the end of the root-system of our batch. [It's] your batch on the 'other side' of the globe.... Nasty plant, no discussion."

Very thoughtfully, she enclosed their specimen, well dried, to me.

De-enveloping it was like unraveling a very long snake's skin.

(Incidentally, one English country name for it is "snake-pipes.")

Our friends are so good to us.

* A weekly series about a municipal garden in Glasgow, Scotland.