The Main Walk stretches east-west from the iconic Fountain, designed by cutler David Mellor, to Trumpington Road. Conceived to bisect the original half of the Botanic Garden that was designed and laid out in the 1840s, the wide gravel path is flanked by majestic, coniferous trees, some of which are amongst the most important trees in the collection.
Both ends of the Main Walk are marked by huge specimens of the Giant Redwood Sequoiadendron giganteum. The two Redwoods opposite one another near the Fountain, with one at the intersection of paths in the centre of the Walk and a further one marking the western end of the Walk date from 1855, and were were grown from the first seed of this species ever brought to England. The seeds were collected by William Lobb in the redwood groves of Calaveras County, California in 1851. Trees were grown and distributed by the nurseryman James Veitch and Son of London. These magnificent trees have reached 30 metres tall in about 145 years. Three young Sequoiadendron trees have been planted, two near the fountain and one by the Trumpington Road Gates, to ensure continuity if the life of these giants proves to be (relatively) short in Cambridge.
The cedars along the Main Walk are venerable and majestic. Three species are present – Cedrus libani from Lebanon, C. atlantica from Morocco, and C. deodara from the Himalayas. The remaining species of Cedar - Cedrus brevifolia from Cyprus - grows in the belt of trees on the eastern border of the Main Lawn.
The most important group of trees on the Main Walk is the collection of subspecies showing variation within the single species Pinus nigra (the Black or Austrian Pine) initially put together by Professor Henslow. The most extreme differences are shown by P. nigra ssp nigra and P. nigra ssp salzmannii, placed opposite one another on the western section of the Main Walk. P. nigra ssp. nigra from Austria is a narrow upright tree with few branches and dense bunches of short stiff needles while P. nigra ssp salzmannii from Spain is a huge spreading tree branching from near the base and with an open canopy of long needles. These subspecies illustrate the extremes of variation within this species.
Charles Darwin spent most of his life studying variation patterns in order to understand the nature of the origin of species. The fact and significance of variation came to Darwin from his mentor Henslow and these trees illustrate this remarkable history.
The Main Walk has specimens of other pines such as P. pinea, coulteri and wallichiana which will ensure that the stateliness and magnificence of the Main Walk will continue into the future.
The fine Trumpington Road Gates date from the late 18th century and were the formal entrance to the old Botanic Garden off Downing Street in the centre of the city. They were reconstructed here in 1909.