The work of scientific investigators, which had been a feature of the sixties, was continued further by a number of gifted men. One of the most out standing was Thomas Kirk who from childhood had been keenly interested in plants. He arrived in New Zealand in 1863 and from then on found many new species, specimens of which he sent to Kew. He, too, made several tours of exploration and his concern for the future of the forest, which in certain districts was facing destruction, was shown in a paper The Utilisation of New Zealand Timbers. His Forest Flora was commissioned by the Government, but unfortunately his greater work, the Flora of New Zealand, was not completed at the time of his death (1898). Kirk's explorations extended to all parts of North and South Islands, and to Stewart Island which he was anxious to see preserved “as a timber reserve”. In many ways he was a source of inspiration to other enthusiasts, not least his son, H. B. Kirk. Kirk's place among the early botanists of this country is shown in the tribute paid him by Cockayne and Phillips Turner who dedicated their book Trees of New Zealand “to the honoured memory of Thomas Kirk, the author of the classical Forest Flora, and for three decades the leader of botanical inquiry in the Colony”.
In Otago at this time was G. M. Thomson, first farmer, then science teacher at Otago Boys' High School, who was an ardent naturalist as was proved by his A New Zealand Naturalist's Calendar. Like Kirk, he noted the drastic consequences of a reckless clearing of the forest cover and issued a warning on the danger of erosion.
Thomson's investigations at Otago were paralleled in greater degree in the north by Thomas Frederic Cheeseman who, from the time of his arrival in New Zealand in 1854 at the age of eight, succumbed to the fascination of plant collecting. After a term of schooling he helped his father on a farm, meanwhile continuing his botanical interests. Inspired by the publication of Darwin's Fertilisation of Orchids, he found the native Pterostylis, a fascinating green-hooded orchid, and watched the visits of insects to this flower. He studied also the method of pollination of rewarewa, Knightia excelsa. He corresponded with botanists in Europe and America, and sent an account of his work on orchids to Hooker at Kew. This reached Darwin who included it in a later edition of his book. Cheeseman formed a field club, and with other enthusiasts tramped over the country surrounding Auckland. In 1887 he thoroughly explored the vegetation of Raoul in the Kermadec Islands and the Three Kings Group. In 1895, with Adams, he explored the far north, on foot, a packhorse carrying collecting material and other gear. He found many small plants, including the tiny colourless parasite dodder (Cassytha paniculata). After a trip through the central volcanic region, Cheeseman visited Mount Cook. In 1896 he was able to visit Cook Islands and spent three months at Rarotonga, where he was a pioneer in the field, and published a full description of the plants. During many of his expeditions Cheeseman was accompanied by his wife. He kept his herbarium, which included specimens of all plants described in his Manual of New Zealand Flora, in special cabinets of kauri in his own home. These are now in the Auckland Museum. For his meticulous work he received world-wide recognition, was elected a member of the Linnean Society, and later received the rare award of the gold medal of that society.