Joseph Dalton Hooker was surgeon and botanist with the Antarctic expedition of 1839, in the course of which he met Colenso at the Bay of Islands. A lasting friendship between these two men was largely responsible for our early knowledge of indigenous plants. They made many excursions together during the three months Hooker spent in New Zealand; on some of these journeys they were accompanied by Andrew Sinclair, another enthusiast. Hooker collected mosses, liverworts, fungi, and seaweeds as well as flowering plants, previously collected by others, and Colenso continued to send to him further specimens during the 50 years these two men corresponded. Hooker succeeded his father as Director of Kew Gardens, and published a Handbook of New Zealand Flora, part of his large six-volume Handbook of Flora.

Another well-known botanist-explorer of the pioneering era was Ernst Dieffenbach who had come to New Zealand in 1839 as ship's surgeon on the Tory. Later, he joined a party of surveyors from the Cuba which explored the Heretaunga Valley where he collected many plants. He was particularly interested in conifers and wrote much on the value of our forests. He climbed Mt. Egmont, travelled through the Taupo area and, further north, saw a kauri forest which was burning. He urged that strict measures be taken to prevent destruction of native trees, even for clearing farmlands. But the most famous collector of the period was William Colenso who came to New Zealand in 1834 as a missionary printer and later entered the church. He was keenly interested in the new country, the Maoris, and their language and customs, but after the visit of Darwin to the Bay of Islands in 1835, his interest in plants greatly increased. He visited many parts of the North Island collecting and observing plants, and was delighted when he first saw a profusion of alpine flowers on the Ruahines. Though he sent specimens to Kew, he also kept some which are now in the Dominion Museum, Wellington.

Still another example of the surgeon cum botanist was Andrew Sinclair who, after a few trips as ship's surgeon, accepted the position of Colonial Secretary offered him by Governor FitzRoy. Eleven years later he retired from office and left for England. But he was soon back and his last venture was an exploratory trip to the Southern Alps with Haast, in the course of which he was drowned in the Rangitata, near the Mesopotamia sheep station. Sinclair contributed much to our knowledge of alpine plants. Similar interests were shown by David Monro. Trained in medicine at Edinburgh, he arrived in New Zealand in the early forties and bought land at Nelson on which he ran sheep. Although politics soon became his main concern (he was Speaker of the House of Representatives for almost a decade), he was the first to explore the vegetation of the northern part of the Southern Alps, and sent alpine plants he collected to Hooker who included them in his New Zealand Flora. Monro's paper on Geographical Botany of Nelson and Marlborough (1865) was the result of careful observation, and three species he discovered were named after him. Lyall was another ship's surgeon whose name is honoured in such plants as Gaya lyallii, Ranunculus lyallii, Olearia lyallii, and a group of Lyallia. He was particularly interested in the lower groups of plants of which he made important collections, and his name was also given to a lichen.

Two other names associated with this early period deserve mention–Travers and Bidwill. W. T. L. Travers, a Resident Magistrate, and his son Henry were early explorers of the Nelson and West Coast districts. Travers was the first white man to pass through the Wairau Gorge and explore the Spenser Mountains and with his son made several botanical expeditions to the Tararuas. Henry also made extensive explorations of the Chatham Islands and brought back many new species, including the giant forget-me-not (Myosotidium nobile). Travers, like many others of his day, was interested in discovering a method whereby fibres of Phormium tenax could be used in the manufacture of cloth, but the results were disappointing. John Carne Bidwill, while acting as representative for his father's firm of merchants, spent most of his short life investigating plants, his enthusiasm even taking him into the territory of Te Heuheu II (Mananui) at Taupo where he climbed the “tapu” peak of the volcano Ngauruhoe then called Tongariro. On this trip he made the first collection of alpine plants to be sent to Kew, including the fascinating little plant later named Forstera bidwillii, in honour of two great botanists. He found kahikatea with masses of scarlet and black berries, which he enjoyed as food. He also collected plants from the Wanganui district and, on a later visit, spent much time in the Nelson area from which he sent a large collection of alpine plants to Hooker.