Scottish horticuluralist William McNab was Superintendent of the Royal Botanic Gardens Edinburgh from 1810, where he was responsible for significantly enlarging and improving the collections.

McNab was born in Knockcavish, Ayrshire, where he assisted on his father's farm before taking up a gardening apprenticeship in Carrick. This was followed by a position in East Lothian in the employ of the earl of Haddington, before he was appointed to the staff of the Royal Botanic Gardens, Kew, in 1801. He was made foreman in 1803 and earned praise from King George III for his involvement with the Kew volunteer infantry. In 1808 he married Elizabeth Whiteman, with whom he had nine children.

In 1810 McNab transferred to Edinburgh on the recommendation of Joseph Banks, and set about augmenting the garden's living collections. He successfully oversaw the move of the gardens to a larger site at Inverleith between 1820 and 1823, during which time he developed an expertise in transplanting techniques. He published Hints on the Planting and General Treatment of Hardy Evergreens in the Climate of Scotland in 1830. In 1825 he had been elected an associate of the Linnean Society.

McNab was especially interested in plants from the Cape of Good Hope, and became an expert on the cultivation of South African Erica, publishing a Treatise on Propagation, Cultivation, and General Treatment of Cape Heaths in 1832. He also came to possess a collection of Erica herbarium specimens collected by James Niven at the Cape. McNab's herbarium was later deposited in the National Museum of Ireland, apart from the Erica specimens, which were acquired by Kew. Erica nabea Guthrie & Bolus was named in his honour.

Under McNab, numerous plants from around the world were brought to the Edinburgh gardens, which in turn supplied plants to other collections. In recognition of his contributions to the Imperial Botanic Gardens in St. Petersburg, the Russian Tsar presented a diamond ring to McNab.

McNab died at the botanic gardens in 1848 and was succeeded by his eldest son, James McNab. His son Gilbert McNab, a medical doctor, also carried out botanical collecting and his eldest daughter, Catherine McNab, published Botany of the Bible (1850-1851).

Sources:
P.D.A. Boyd, 2009, "McNab, William (1780-1848)", Oxford Dictionary of National Biography, online edn:
www.oxforddnb.com/view/article/99631, accessed 1 November 2012

M. and L. Fraser, 2011, The Smallest Kingdom: 156
E.C. Nelson and J.P. Rourke, 1993, "James Niven (1776-1827), a Scottish Botanical Collector at the Cape of Good Hope. His Hortus siccus at the National Botanic Gardens, Glasnevin, Dublin (DBN), and the Royal Botanic Gardens, Kew (K)", Kew Bulletin, 48(4): 663-682.