Urban gardener, Cleve West: Sumach the better

Marcia and Gerald's sumach has come up blind this year. A shame, as I was hoping to cut one of the flowers for an experiment. Their garden was, I think, the last one I built before design work became more regular, and I have flagrantly taken advantage of our lasting friendship by dropping in for cuttings, photos of plants and cups of tea. The garden, a mixture of decking and gravel, has been - aside from a biennial clean with a pressure sprayer to stop the boards becoming an ice rink - relatively easy to maintain over the years, and the sumach has provided a gentle whiff of architecture among softer perennials and herbs. The drought may have impeded the tree's ability to flower and set seed this year, though some untimely pruning could have been the main cause.

Despite its tendency to sucker (and this makes it easy to propagate), a well-shaped Rhus typhina (Staghorn Sumach) is a useful tree for an urban garden. Native to rocky hillsides of eastern USA (where its suckering habit is a survival technique), it has flourished in the ornamental garden. Slender, alternate, pinnate leaves on downy stems like deer antlers (that give it its common name) are topped at this time of year by clusters of deep crimson velvety drupes. Where conditions allow, a tree can reach a height of 6-8m, its open, flat crown making it a beautiful form both with leaves or without; it's therefore best placed where it can be silhouetted in winter sunshine. If space is limited, it can be pruned, or you could choose Rhus glabra (the Mountain or Smooth Sumach), which grows more like a large shrub at 2-3m.

The Rhus family is highly valued in its native America, and not only for its good looks. The bark and drupes of the sumach are high in tannin and it's therefore used to tan leather. Medicinally, it is said to treat anything from venereal disease to piles, bed-wetting to warts. A close relative, Rhus vernix (or Toxicodendron vernix), is altogether more potent as its common name, Poison Sumach, suggests. The sap (containing pentadecacatechol) is extremely poisonous, causing severe dermatitis in some people even from indirect contact. Such high levels of toxicity means it's a plant that's more than capable of looking after itself and, apart from coral spot, is resistant to most diseases, even honey fungus.

But it's the fruit of Staghorn Sumach that has captured my imagination. I have known for many years that it was used by American Indians to add a citrus flavour to water, but have never tried it for myself. So, with no luck at Marcia and Gerald's, I have for the first time resorted to scrumping, albeit from the relative safety of a public footpath. Interestingly, when I mentioned 'scrumping' to someone in their teens recently, they hadn't heard of the term. The momentary pang of nostalgia that had me lamenting a lost pastime was quickly snuffed out when I remembered the recent bout of thieving at the allotment. It's only the term that's been lost, not the deed. In the excitement and tension of scrumping, the important thing is not to get confused - making a drink from the Poison Sumach would make Dr Jekyll and Mr Hyde sound like a children's bedtime story. Fortunately, the drupes of each tree are quite different. Those of the poisonous varieties are smooth, whereas the Staghorn Sumach's fruit is covered with downy crimson hairs.

My plunder (from an overhanging branch that would have had someone's eye out if I hadn't administered the necessary judicious pruning) was steeped in cold water for half an hour before being strained for tasting. Sure enough, a hint of lemon and quite refreshing. Left to stand overnight it became more astringent, with more tamarind than lemon, and not so palatable. It's hardly a drink that will put R Whites out of business - but it's nice to try these things if only to verify the facts, fulfil a latent desire to scrump and become, for a moment at least, a secret lemonade drinker.