• Jackman, George (1801-1869)

The Jackman Nursery was founded by William Jackman (1763-1840) in 1810 on 50 acres of land at St. Johns, Woking, Surrey, England. His son, George Jackman, became a renowned clematis hybridizer. The specific epithet, jackmanii, as in Clematis x jackmanii was named for him.

George Jackman II (1837-1887) followed his father in the nursery business which sold a wide range of plant material in addition to the famous clematis cultivars.

• Jefferson, Thomas (1743-1826).

In addition to the many hats the third President of the United States wore as architect, statesman and politician, he was also an agriculturist, horticulturist, and landscape designer. After designing several estates for friends, he eventually designed his own home landscape at Monticello.

In his designs, Jefferson fused the elements of neo-classicism, such as terraces and symmetrically curved paths, with elements he learned about from his tours of English landscapes--the natural vistas combined with informal shrub and flowers beds.

Throughout, and to the end of his life, Jefferson was a devoted gardener and landscaper. He once wrote, "Though an old man, I am but a young gardener." In 1811 he wrote, "No occupation is so delightful to me as the culture of the earth, and no culture comparable to that of the garden."

The species, Jeffersonia diphylla or Twinleaf is named for him.

• Jeffrey, John (1826-53)

Scottish botanist and explorer who collected plants and seeds in Oregon and California in the United States. He disappeared in 1852 on a trip from San Diego across the Colorado Desert and was never seen again.

The species of pine, Pinus jeffreyi, is named for him.

• Jekyll, Gertrude (1843-1932)

Gertrude Jekyll's book 'Wood and Garden' (1899) had an enormous influence on the English (and hence the world's) attitude toward landscape gardens. She saw beauty in natural effects.

She collaborated in garden design with architect Sir Edwin Lutyens. They first met in 1889 ". . . at a tea table, the silver kettle and the conversation reflecting rhododendrons, . . ." as Lutyens described it.

She is most closely associated with the garden at Bois des Moutiers, near Dieppe, France and Hestercombe in Somerset.

Her planting designs were used at Broughton Castle in Oxfordshire, Manor House Upton Grey, Lindisfarne Castle in Northumberland, Hatchlands in Surrey and Knebworth in Hertfordshire.

She is recognized as one of the greatest influence in the 20^th century on the design of herbaceous gardens. Known for her use of flowers and color in garden designs, she also used them in woodlands, herbaceous borders, and water gardens. Planned graduations of color are particularly evident in her designs.

Plants associated with her include Helleborus foetidus 'Miss Jekyll's Scented', Lavandula angustifolia 'Munstead', Nigella damascena 'Miss Jekyll', Pulmonaria angustifolia 'Munstead Blue' Sedum telephium 'Munstead Red', Solenostemon 'Gertrude Jekyll' and Vinca minor f. alba 'Gertrude Jekyll'.

• Jellicoe, Sir Geoffrey (1900-1996)

Joint author with J.C.Shepherd of the classic Italian Gardens of the Renaissance. Other books were The Landscape of Man (1975) and Baroque Gardens of Austria.

Sir Geoffrey's designs were used at Ditchley Park, Sandringham, Sutton Place in Surrey, Shute House in Dorset, Cliveden (rose garden) in Buckinghamshire, Cottesbroke Hall in Northamptonshire, Mottisfont Abbey in Hampshire and the Moody Historical Gardens in Texas. He created the Kennedy Memorial at Runnymede and the fine canal at the RHS garden at Wisley.

• Jensen, Jens  (1860-1951)

Born in Denmark, Jensen became a renowned landscape architect in the United States. He designed Columbus Park in Chicago and the park system of Racine, Wisconsin.

His major contribution to landscaping was the refinement of the use of plant masses in a "prairie style" of design that lent itself to a more informal or "natural" effect in the landscape. He also advocated using existing trees and shrubs on a property as an indicator of existing soil conditions and to use these as a reference in selecting plants for a site.

• Johnston, Major Lawrence (1871-1958)

He was the creator of the Hidcote Manor Garden in Gloucestershire and originator of various plant varieties including Verbena 'Lawrence Johnston' and Hypericum 'Hidcote'.

Major Johnston was born in Paris of an English mother and American father. He personally collected many plants from Africa and China on a plant expedition in the 1920s.