English-born missionary, printer and naturalist who worked in early 19th century New Zealand. Colenso was an untiring collector and early botanical explorer of the North Island of New Zealand.

William Colenso was born in Penzance, Cornwall, where he was apprenticed as a printer and bookbinder and as a young man joined the Penzance Natural History and Antiquarian Society. After a period working for the London firm of Richard Watts, printers to the Church Missionary Society, he put himself forward for the post of missionary-printer to run a small printing press at the Paihia missionary station in New Zealand. Successful in his application, he arrived at Paihia in the Bay of Islands in January 1835, where he set to work. Colenso's books, including copies of the New Testament in the Maori language, were the first to be produced in New Zealand; achieved in spite of his not being provided with the proper equipment and stationery. In 1840 he printed the Maori text of the Treaty of Waitangi and also published his observations of the event of its signing.

Following his first exploratory trips in 1838 and 1839 (to the East Coast with the Rev. William Williams and to the north coast with the Rev. W. Wade), Colenso travelled a great deal in the North Island, learning much about the Maori and the country's natural history. He collected plants industriously, sending the fruits of his labours to Kew and to his old friends at the Penzance Natural History Society. In 1841 he tramped to Poverty Bay and Lake Waikaremoana, where he found the filmy fern he named Hymenophyllum pulcherrimum Col. and the tree fern he called Dicksonia lanata Col. He went on to traverse the length of the land from Cape Terawiti to Cape Maria Van Diemen, and was the first European to cross the Ruahine Mountains, where he gathered specimens of alpine vegetation. Having received encouragement with the visits of Charles Darwin (1835), Allan Cunningham (1838) and J.D. Hooker (1841), his botanical writings were voluminous, mostly published in the Transactions of the New Zealand Institute (of which he was a founder member). As well ass his botanical publications he wrote of the fossil remains of the moa and published many works on the Maori.

Colenso's longest journey was made in 1843-1844 when he was sent to select a site for a mission at Hawke's Bay. Travelling from Hicks Bay on the east coast he sailed from Taranganui to the Wairarapa coast at present day Castlepoint. With Maori guides, Colenso and William Williams walked north to the Ahuriri district (present day Napier) and a site was selected for the mission near present day Clive. Colenso explored further north and inland before returning to Paihia via Tauranga, Waikato, Otahuhu and Kaipara Harbour.

Having trained at St. John's College, Colenso married Elizabeth Fairburn in 1843 and was ordained as a deacon in 1844. Together with their first daughter the couple moved to Hawke's Bay that year, where Colenso was put in charge of the new mission station. An aggressive evangelist, Colenso assumed his responsibilities with fervour. While he converted many Maori to begin with, his intolerance turned many away from the church in the following years. It was at this time that Colenso first crossed the Ruahine Range with Maori help, reaching the Rangitikei district. In 1847 he travelled from Ahuriri to Lake Taupo and explored south across the Onetapu and Rangipo deserts. He returned inland five more times during his years at the mission.

In 1852 Colenso was suspended from his duties. He had not only displeased the Anglican establishment with his zealous ways, but also earned the wrath of settlers in the vicinity for his opposition to Maori land sales. Friction was also increasing with Maori leaders thanks to his overbearing and humourless nature, while his home life was marred by a loveless marriage. At some point he embarked on an affair with a Maori woman employed in his household, and she bore his child in 1851, leading Colenso's wife to leave him. Elizabeth Colenso was further distressed after her request that her own family take care of the illegitimate child met with refusal.

Colenso's behaviour thus brought his downfall from the clergy and he withdrew from society for some years, ridiculed by the Maori, whose own habits of infidelity he had condemned. He re-emerged in 1858, when he entered the world of politics by election to the Hawke's Bay Provincial Council for Napier Town. From 1861-1866 he represented Napier in the General Assembly, but eventually his lack of tact and inability to compromise lost him support. At this time he turned more and more to botanical work, publishing copious papers on the subject. He was also commissioned to complete a Maori dictionary in 1865, though funding ran out before its completion and only a section of it was published before his death. In recognition of his scientific endeavour, Colenso was awarded a Fellowship of the Royal Society of London in 1886. He was readmitted to the clergy in 1894, five years before his death.

Many of his own descriptions of new taxa were rejected, but Colenso's contribution to botany in terms of collecting was significant, especially the large shipments of plants he sent to J.D. Hooker. Among the taxa named in his honour was the genus Colensoa Hook.f. (basionym of Lobelia sect. Colensoa (Hook.f.) J.Murata), the tree fern Cyathea colensoi Domin (=Alsophila colensoi Hook.f.) a mistletoe, Elytranthe colensoi Engl. (=Loranthus colensoi Hoof.f.) and the mountain flax Phormium colensoi Hook.f. While Colenso sent most of his collections to Kew, those he kept in New Zealand passed into the keeping of the Hawke's Bay Philosophical Institute (Hawke's Bay branch of the Royal Society of New Zealand), from whence the herbarium was acquired by the Dominion Museum. Colenso specimens are now found at AK, PDD and WELT.

Sources:
A.G. Bagnall and G.C. Petersen, 1948, William Colenso, his Life and Journeys
L. Cockayne, 1919, New Zealand Plants and their Story: 19-21
D. Mackay, 2007, "Colenso, William 1811-1899", Dictionary of New Zealand Biography.