Sweet pea

Sweet Pea (Lathyrus odoratus) is a flowering plant in the genus Lathyrus in the family Fabaceae (legumes), native to the eastern Mediterranean region from Sicily east to Crete.

It is an annual climbing plant, growing to a height of 1-2 m where suitable support is available. The leaves are pinnate with two leaflets and a terminal tendril, this twining round supporting plants to help it climb. The flowers are purple, 2-3.5 cm broad, in the wild plant, larger and very variable in colour in the many cultivars. Unlike most peas, the seeds of the sweet pea are poisonous as they contain a neurotoxin, and should not be eaten. The illness caused by the ingestion of sweet peas is known as odoratism, or sweet pea lathyrism.

Sweet peas have been cultivated since the 17th century and a vast number of cultivars are commercially available. They are often grown by gardeners for their bright colours and the sweet fragrance that gives them their name.

Horticultural development
Henry Eckford (died 1906), a nurseryman of Scottish descent, cross-bred and developed the sweet pea, turning it from a rather insignificant, if sweetly scented flower, into the floral sensation of the late Victorian era.

His initial success and recognition came while serving as head gardener for the Earl of Radnor, raising new cultivars of pelargoniums and dahlias. In 1870 he went to work for one Dr Sankey of Sandywell near Gloucester. A member of the Royal Horticultural Society, he was awarded a First Class Certificate (the top award) in 1882 for introducing the sweet pea cultivar 'Bronze Prince', marking the start of association with the flower.

In 1888 he set up his development and trial fields for Sweet Peas in the North Shropshire market town of Wem. By 1901, he had introduced a total of 115 cultivars, out of total 264 cultivars grown at the time. Eckford was presented with the Royal Horticultural Society's Victoria Medal of Honour for his work. He died in 1906 but his work was continued, for a time at least, by his son John Eckford.

More lately, the association between the sweet pea, the Eckfords and Wem has been highlighted again. In the late 1980s, the Sweet Pea Society of Wem started an annual Sweet Pea show and the town has again taken the flower to its heart. Many of the street signs now carry a sweet pea motif and an area of the town is known as Eckford Park.

Genetics
Gregor Mendel is today recognized as the "Father of Modern Genetics" for his work with the cross breeding of pea plants (Pisum sativum) with different characteristics, and sweet pea has been used in a similar way. The Sweet Pea is thus a model organism being used in early experimentations in genetics, particularly by the pioneer geneticist Reginald Punnett. It is highly suitable as a genetic subject because of its ability to self-pollinate and its easily observed Mendelian traits such as color, height and petal form. Many genetical principles were discovered or confirmed in sweet pea. It was used by Punnett in early studies of genetic linkage. Complementary factor inheritance was also elucidated in sweet pea, from the cross of two pure-breeding white strains which gave rise to a blue hybrid, the blue colour requiring two genes, derived independently from the two white parents Like the blue rose, the yellow sweet pea remains elusive, and a true yellow is unlikely to ever be achieved without genetic engineering.