Another Root Less Travelled: Silverweed

Imagine a not-uncommon weed, one which any self-respecting gardener would evict from her garden with alacrity. A bed choking thug, which although short in stature, compensates by spreading sideways with panzer-like rapidity.  It turns out that this self-same plant has been helping keep the hungry alive on several continents for centuries.  Even more incredibly, it is now doing sterling work in preventing infant malnutrition.

So who, or what is this sinning saint, this sweetpotato of the north? I'm talking about none other than silverweed (Potentilla anserina). Even if you don't know this plant, the chances are that you've walked on it or passed close by.  

Image courtesy of www.donaleaplantbrokers.com/

It's a rather beautiful plant, forming low growing tufts, with silkily haired leaves which give it that eponymous silvery sheen.  Dotted amongst the leaves, during the growing season, are pretty, bright yellow, five-petalled flowers, which help establish its identity as a Potentilla. This combination of two precious metals on the one plant accounts for a common French name, richette.



Actually, botany's grand panjandrums have seen fit to rename it Argentina anserina, but in the pugilistic world of plant systematics, this change has not gone unchallenged - the gloves are off and it's Round Two.  I'm personally hoping that the cocky upstart is decked by a swift left hook and Potentilla is reinstated.  I won't cry for you, Argentina.

As the season progresses, silverweed sends out wiry red stolons which root along their length, establishing daughter plants at every node.  Large colonies build up rapidly.  You have been warned.

I remember my surprise when I first evicted a few small clumps from a friend's garden.  Astonishingly, they had long roots.  Even more astonishingly, they were slightly thickened, particularly at the ends, in a way that is sort of reminiscent of the Chinese yam (Dioscorea batatas).   It was possible, in a state of intense hunger, to imagine how it might be worth harvesting and cooking these roots, in lieu of any other carbohydrate staples.  That dog-eared old
copy of Food for Free, whose entry on silverweed I had doubted, wasn't lying after all.

The region of Britain that is most associated with silverweed harvest is Scotland, more specifically, the Outer Hebrides.  On North Uist, in a certain place, according to folklorist Alexander Carmichael, a man could sustain himself on a square of ground of his own length.  Either the silverweed of Uist is remarkably productive or he meant a single day's ration. Perhaps a kind inhabitant of said island paradise would like to confirm or deny these rumours. If true, would she please send me a specimen of brisgean, as it is known in Gaelic, for further evaluation.

Over on the other side of the world, along the Pacific seaboard of British Columbia,  silverweed harvesting was also carried out in an intensive way.  Harvesting, frankly, is not an adequate description of the highly organised approach to crop management that was used by the First Nations of this area.  Like with the camas crop, this was really horticulture. In fact both species were sometimes cooked together, along with the rhizomes of a clover, Trifolium wormskioldii.  Elaborate gardens were constructed, sometimes involving dry stone walls and their ownership was jealously guarded.

To get further information on silverweed and its cultivation and preparation in that area,  I contacted Professor Nancy Turner at the University of Victoria in British Columbia.  She is a renowned ethnobotanist and has carried out research into silverweed and several other native root crops of the area.  Her studies show that silverweed roots have a comparable food value to that of the potato, with the added advantage of higher calcium and magnesium levels.  Traditionally the roots were steamed in pits and eaten with an oil condiment, a favourite being ooligan (or eulachon) grease, produced from the shoals of smelt that abound in the area.  Some native people have compared the taste to that of sweetpotato. Occasionally the cultivated roots reach a diameter of 7mm, which is really quite impressive.  The Pacific silverweed is often classified as a separate sub-species P. anserina ssp pacifica or as P. egedii and is distinctly less silvery than the plant that I know and love.  

Abe Lloyd, one of Nancy's students, told me about his research into traditional silverweed gardening methods in British Columbia.  Abe has been restoring First Nation silverweed plots that were abandoned about 50 or 60 years ago, using a combination of weeding and tilling.  Favoured sites are generally found along estuaries in moist, sandy soil.  The traditional tool of choice is a digging stick made of Pacific yew. Yields sound quite good to me: about 710lbs per acre according to Abe, this being an average from the 60 plots he managed as part of his MSc project.

All this may seem to be a sufficiently ringing endorsement of silverweed to send you scuttling to nearby gravelly river banks or estuaries in search of it.  But no, there's more.  High up on the Tibetan Plateau, droma, as silverweed is known, is being incorporated into the barley-based diet of young children. Silverweed's amino acid profile complements the barley's and creates a complete protein, presumably supplying the lysine that the barley lacks.  In any case, the Terma Foundation has been promoting a return to silverweed consumption as a way of ensuring that the next generation of Tibetans are strong and healthy.  It's a common plant there and as the name Potentilla suggests, it also has medicinal uses.

Silverweed is one of those foods which the potato (damn its eyes!) seems to have driven from our plates out to the badlands, with the status of vegetable pariah.  Perhaps it's time for reacquaintance and re-evaluation. So, in the spirit of enquiry, I decided to investigate further.  Last spring I collected some silverweed shoots from a few locations and potted them on.  I left them alone pretty much thereafter, apart from watering them. 

I also had my eye on a wild stand, growing, true to type, by the water's edge in gravelly soil.  The plants die back quite early in the autumn, so I headed out while the leaves were still visible.  Armed with a trowel and a bag, I set about excavating the plants and their roots.  

Initial yields were puny: I discovered that the densest growth at the centre of the clumps produced no thickened roots. Dispersed clumps proved to be more rewarding.  It was easy to see how the very act of harvesting, with associated disturbance and thinning, might benefit the harvester by reducing competition between the clumps.

Encouraged by my success, I went home and harvested the potted plants.  This is how the roots looked after I'd cleaned them.









So what did they taste like? I took the largest of the roots and boiled them for a few minutes. They had a starchy, somewhat nutty taste, with just a hint of bitterness.  I was surprised to find that they were, as our ancestors knew, perfectly suitable for eating.

So silverweed may really deserve the precious allusions its name conjures in the mind.  It's frost hardy and easy to grow; it's certainly vigorous.  It is even, to my mind, an attractive plant too. The roots may diverge a little from the bulky ovoid shape typified by the potato, but that doesn't seem to have hindered spaghetti's adoption as a common foodstuff. Silverweed's roots are thicker than spaghetti strands, have their own flavour and are nutritious.  With a bit of selection for taste and yield, this could be an interesting low maintenance crop for adventurous gardeners.  The first step is to locate superior wild strains.  That's where you come in.  If you've got a digging stick and time on your hands, you can help me find the finest silverweed varieties for yet another Radix breeding programme. Tempted?