Urban gardener, Cleve West: Weed or wonder?

A year or two before I took my first tentative steps in the world of gardening, my mother brought back a curious plant from a friend. Neither of us had seen it before and together, admiring its feathery foliage, we thought it handsome enough to plant in a bed that had been cleared of

ground elder. Weeks later, proud of our apparent green-fingered ability to make this plant thrive, a garden-savvy friend (once she'd re-gained composure after nearly wetting herself laughing) gave us the low-down on 'Field Horsetail' ( Equisetum arvense), one of the most pernicious weeds around.

A more recent encounter with the genus was at my allotment last year where a thin strand of 'Marsh Horsetail' ( E. palustre) appeared in the greenhouse. An allotment neighbour has been digging it up for several years but I'd never seen any evidence of migration in my direction. Its appearance inside the greenhouse was both alarming and comical, the lonely strand looking as embarrassed as a tunnelling POW, having misjudged his escape route, mistakenly emerging in front of a gun turret. It was yanked out without a second thought.

Equisetum arvense, literally meaning "horse and bristle of the field", is our most common horsetail. Not to be confused with mare's tail, the unrelated aquatic Hippuris vulgaris, its invasive reputation is largely due to the physical strength of its deep, thread-like rhizomes (which will give anything but a sharp spade a run for its money) and its ability to dig deep (1.8m) for the moisture it needs to survive. Like ferns it is non-flowering and reproduces by spores, these ones being produced on conifer-cone-like leaf clusters. It can also propagate from shoots and leaves that emerge from nodes. But despite its reputation for being one of the most difficult weeds to eradicate, it's impossible not to respect the tenacity of this primitive, vascular plant that has kicked about this planet for more than 350 million years.

Emerging spears, looking like miniature parasol mushrooms, are designed to push through the most compacted wasteland (of which they are particularly associated), before elongating to reveal brownish hoops edged with bristles. The stem is hollow with an unusual segmented composition (ie, node at each end), and can be pulled apart with the same idle fascination as popping bubble wrap. Come June the stems unfurl thin branchlets (their leaves) like an umbrella to produce a haze of green foliage, a common sight along railway embankments where other colonisers such as ivy, buddleia and the dreaded Japanese knotweed pursue a perpetual battle for territory.

Before Brillo pads, silica crystals on the leaves and stems of horsetail made them a valuable abrasive (giving them another common name, 'The Scouring Rush') and were used as light sandpaper for fine carpentry and metal work. Medicinally, it is valued as a diuretic, antiseptic and an astringent, while cosmetically it can help toughen fingernails. An infusion under a hot tap is said to make a relaxing bath tonic. But where it earns most respect from the gardener is in its use as a fungicide. An infusion of the stem and fine leaves (made by simmering them in water for half an hour) can be used to spray against mildew, rust and black spot. While in theory this sounds organic, using it on vegetables and herbs has not yet received the Soil Association's seal of approval.

The only horsetail I've really used with confidence in a domestic garden is the 'Dutch Rush' ( Equisetum hyemale), a marginal plant often placed in shallow ponds where its ability to spread can be curtailed in a pot. But if I had the space (a ditch perhaps) I would recklessly experiment with the 'Field Horsetail' and perhaps even the 'Giant Horsetail' ( E. telmateia), a triffid of a plant that can grow to 1.5m (5ft), making it a dramatic accessory for maverick flower arrangers.

Your neighbours certainly won't thank you for trying to introduce these species anywhere near your boundaries, so don't let my enthusiasm for them get you into trouble. Curiously though, it may not be as easy to propagate as I thought, for unlike bindweed, couch grass and ground elder, horsetail can be fussy when its roots are fiddled with and it needs plenty of moisture to find its feet. The fact that my mother and I, with barely an ounce of horticultural knowledge between us, managed to get it to grow all those years ago was simply beginner's luck and, proud of our apparent green fingers, blissful ignorance proved a potent introduction.