Lord Anson's Pea

This beautiful perennial sweet pea is at last becoming popular after rather a chequered past. Fay Sharman relates its history and explains how to grow it

The Sweet Pea reached this country nearly three hundred years ago and has been a firm favourite ever since - as necessary to an English summer as strawberries and cream. It has many beautiful relatives in the genus Lathyrus (named from the ancient Greek word for pea), with the same climbing habit and distinctive butterfly flowers. But only a few of these have been adopted by gardeners and none has even approached the popularity enjoyed by the Sweet Pea.

One of the most desirable and, until recently, most elusive species is Lathyrus nervosus. Lord Anson's Pea, as it is called, was originally introduced in 1744 and belongs to a dramatic episode in our seafaring history. The story begins in 1740, when Lord George Anson was given command of a squadron and set sail for the Pacific to defend English interests against the Spanish. Battered by storms off Cape Horn, he arrived in a Patagonian port with only one of his six ships, the Centurion, unscathed and his crew much reduced in number. Scurvy, caused by a lack of fresh vegetables, had already taken its toll after a year at sea and it is not surprising that, once ashore, the sailors found 'these Peas (i.e. L. nervosus) were a great relief.' The Centurion's cook sensibly took some of the peas with him and eventually brought them back to England.

Lord Anson, meanwhile, decided to continue towards China in pursuit of a Spanish treasure ship which plied between Mexico and the Phillippines. Off the coast of Manila in 1743 the tiny Centurion caught up with and captured the great galleon, returning home via the Cape of Good Hope in 1744. His lordship was promoted to the rank of admiral and, as a result of his daring circumnavigation of the globe, won both fame and fortune. He used part of the proceeds to extend the family home at Shugborough in Suffolk (now a property of the National Trust).

After its initial introduction by Lord Anson' s cook, L. nervosus was grown in the Chelsea Physic Garden in London before apparently dying out. At first it was known as Pisum americanum or the Cape Horn Pea. It was reintroduced in 1834, probably from Uruguay, and again in about 1839, when the Duke of Bedford received seeds from a settler in South America. This time it survived cultivation until the end of the century. It was now generally referred to as Lord Anson' s Pea, although its botanical name remained uncertain and it was frequently confused with another South American species, L. magellanicus. To make matters worse, unscrupulous nurserymen sometimes offered the common Chickling Pea, L. sativus, instead of it.

Yet another introduction of L. nervosus, on this occasion correctly named, was made in 1926. With the bestowal of an Award of Merit by the Royal Horticultural Society in 1928, it seemed to have arrived at last. But confusion persisted, for in the early 1970s the RHS Garden at Wisley was sent some seeds from a South American botanic garden under the name L. magellanicus, which turned out to be L. nervosus, Fortunately, this latest introduction has been the most successful so far. After its chequered career. Lord Anson's Pea is now relatively secure in cultivation both in Britain and the USA. It may be seen in several great gardens, including Sissinghurst and, appropriately enough, the Chelsea Physic Garden, where it was first grown, and Shugborough, the former home of Lord Anson. It is also available from seed companies.

This delightful plant is certainly well worth growing and has the advantage over its cousin, the Sweet Pea, that it is perennial not annual. A climber to about 2-3ft (60-90cm) high, or as much as 6ft (1.8m) when established, it clings to any suitable support by means of very long tendrils. The leaves are a pleasant greyish green, while the flowers, in clusters of four or five, are sweetly scented and typically pea-like; they vary in colour from an unusual clear blue to a more purplish shade fading to almost white in the centre. The plant is covered in bloom all through the summer.

The rival L. magellanicus, with which L. nervosus has been so often wrongly identified, was finally introduced from Argentina in the 1920s. The chief distinction between the two species is the leaves: those of L. nervosus are completely smooth, as opposed to slightly hairy in L. magellanicus, and characterised by a hard thickened margin, which L. magellanicus lacks. It is understandable that botanists have had such difficulty in telling them apart, particularly as their native habitats overlap. Although L. magellanicus gained an Award of Merit in 1929, it is probably no longer in cultivation and surely deserves to be reintroduced.

In the wild L. nervosus inhabits coastal areas and lake sides, growing in open soil and scrub. It is a native of Argentina (north to 378S latitude), Chile (north to 468S), Uruguay and southern Brazil. In cultivation it has gained a somewhat temperamental reputation which is entirely unjustified. Just as it resembles the Sweet Pea, or a nobler version, so it may be treated in almost exactly the same way.

For best results, seed should be sown outside in early autumn in pots or boxes filled with seed or potting compost. The young plants are then pricked out soon after germination into individual 3½inch (9cm) pots and over-wintered in a cold frame. They may be planted out in early spring when the weather allows, in well drained soil, or alternatively transferred to large 10in (25cm) pots and grown in a cool greenhouse or conservatory. Some form of support, such as wires, twiggy sticks or trellis, should be provided for the plants to clamber up.

Although the lifespan of L. nervosus is usually only about five years, it is perfectly perennial. It will flower well in the first year and even more profusely after that, producing its lovely blooms throughout the summer if deadheaded regularly. It tends to die back a bit in the winter, but don't be alarmed: it should be quite happy out of doors once you have found the right spot for it - perhaps trained against a warm south-facing wall. Since it is so easily raised from seed, you have room to experiment and there is no reason why Lord Anson's Pea should not thrive in most gardens.