[1] Wight was the son of a solicitor (Writer to the Signet) in Edinburgh who came from a line of East Lothian tenant farmers.

His devotion to botany was clear from the start and his earliest collections were made around Samalkota, Rajahmundry and Masulipatam in the Northern Circars in the present-day state of Andhra Pradesh.

[6] In 1828 the Governor of Madras, Stephen Rumbold Lushington, scrapped the Naturalist's post,[7] and its collections (including Wight's own, and earlier ones of Patrick Russell and the Tranquebar Missionaries) were sent to the Company headquarters in London.

[3] From here, in 1828, he began a productive correspondence with William Hooker, Professor of Botany at Glasgow University, sending him plant specimens and drawings by his Indian artist Rungiah.

[4] Nathaniel Wallich was then in London curating the great East India Company herbarium, which contained the Madras Naturalists' collection.

During this leave, Wight spent much time in Scotland where the two men worked on the collections and distributed up to 20 sets of duplicates to specialists in Britain, Europe, America and Russia.

Wight & Arnott embarked on three joint publications: a Catalogue of the herbarium specimens (reproduced lithographically as was done by Wallich), a Peninsular Flora arranged according to the natural system, and a volume of monographs, mainly by other authors, of three significant plant families.

Shortly thereafter came the Contributions to the Flora of India under Wight's name, containing accounts of the families Asclepiadaceae (by himself and Arnott), Cyperaceae (by Christian Nees von Esenbeck) and Compositae (by Augustin Pyramus de Candolle).

The transfer was based on references from Hooker and Robert Brown, the Governor Sir Frederick Adam advised by J.G.

[6] This was a major project of the Madras Government with a spending of almost 500,000 Rupees (about £2.5 million in today's terms) to induce Indian tenant farmers (ryots) to grow introduced long-staple American Cotton and to process it using the saw gin, so that it could be exported for spinning and weaving in Manchester.

The cotton was grown by ryots on farms that covered a range of soils and climatic regimes from Salem in the north to Courtallam in the south.

The experiment was, however, deemed a failure, though largely due to economic reasons,[13][14] and long-staple cottons did not supersede indigenous diploid varieties until the early 20th century.

In 1865 Wight was a member of the committee that helped Edward John Waring edit the Pharmacopoeia of India (published in 1868) and in 1866 he read a paper on On the Phenomenon of Vegetation in the Indian Spring[19] to the International Botanical Congress in London.

He donated his vast collection of duplicates to the Kew Herbarium, which included 3108 species of higher plants and 94 of ferns, distributed in 1869/70 in 20 sets to herbaria in Europe, Russia, North America, South Africa, Australia and, for the first time, to two South Asian herbaria (Calcutta and Peradeniya).

In October 1871, shortly before his death Wight gave his best specimens to Kew, which included the types of the species described in his publications.

[6][22] Unlike some of his other medical contemporaries Wight was not successful financially, he left moveable estate worth less than £2000 (about £200,000 in today's terms),[23] and Grazeley had to be sold immediately after his death.