In 1831, his finding at Killarney of the beautiful moss Hookeria laetevirens, hitherto unknown in Ireland, led to the formation of one of the warmest and most valuable friendships of his life. He forwarded specimens, with a characteristic letter, to W. J. Hooker at Glasgow, and the kind and encouraging reply which he received led to further letters and eventually to an intimacy which seems to have been prized equally on both sides. Hooker recognized at once the extraordinary talent of the shy young man of twenty, lent him books, asked him to visit him, and congratulated him on his critical faculty, predicting for him a rapid advance to "the top of algologists." Another life-long friendship made about this time was with Mrs Griffiths of Torquay; and he numbered Greville and Agardh among his earliest correspondents. Already he was deep in his life-task of comparing and describing plants, working with the restless energy which characterised him. "I rise at five every morning," he writes, "and work till breakfast, examining or describing the Algae for the 'British Flora[109].' If I do five species a day I think it good work. This may seem slow, but there is much to be compared and corrected! for I differ from Dr Hooker on many species. Oh, impudence! oh, presumption!" In 1832 he undertook to do the Algae for J. T. Mackay's Flora Hibernica, which was published three years later; this was his most important contribution to the botany of his native land.
The death of his father in 1834 broke up Harvey's home life, and his strong desire to study the vegetation of distant countries led to enquiries as to the obtaining of an appointment in the Colonies. New South Wales was first thought of, but it was for the Cape that he started in the following year.
Asa Gray, a friend of many years' standing, tells, in a notice of Harvey in the American Journal of Science and Arts[110], a curious story as to the circumstances attending this momentous change in Harvey's life. The story is repeated in the notice of Harvey in Seemann's Journal of Botany[111], though not mentioned in the Memoir edited by his cousin. It seems that, as the result of Harvey's representations, he obtained through Mr Spring Rice, afterwards Lord Monteagle, the post of Treasurer at the Cape; but, by an accident, the appointment was made out in the name of an elder brother (Joseph Harvey); and an inopportune change of ministry occurring just at the time, frustrated all attempts at rectification. Be that as it may, Joseph Harvey sailed for South Africa in July 1835, taking his younger brother with him as assistant.
It was with high hopes that the naturalist started for the Southern Hemisphere. At that time the flora of South Africa was but slightly known. About Cape Town itself and near other older centres of colonization, indeed, many plants had been collected, both by Dutch and English; but vast tracts of mountain and veldt, for a thousand miles to north and east, were still unexplored. He describes his excitement on landing, and how, after a sleepless night, he started off for the hills early next morning, to revel among strange Ericas, Polygalas, Lobelias, Diosmas, Proteas, and Ixias. He at once settled down to collecting with his usual method and energy. From four or five until nine every morning he was at work on the mountains or on the shore; after which several hours were devoted to preserving the material. Within a few weeks he was engaged on the description of new genera and species, and in three months his herbarium contained 800 species. Already schemes for organized work leading up to publication were in his mind; and it seemed as if his task lay open before him; but fate willed otherwise. His brother fell ill within a few months of his arrival, and a little later a return to Europe was ordered—to no purpose, as Joseph Harvey died on 26 April, a fortnight after sailing, and it was a sad home-coming which the naturalist, who had accompanied the invalid, experienced in the June following. He started again for South Africa a few weeks later, to take up his brother's duties as Colonial Treasurer; and remained there for three years, when severe illness, brought on by overwork, compelled a return home. But he came back, and resumed his strenuous life, spending his days in official duties and his nights at botany, until, in 1842, a complete break-down forced him to resign his post, and leave the country. Seven years of his life were thus devoted to South Africa, and, in spite of the serious inroads on his time and energy caused by two tedious voyages home, as well as by illness when at the Cape, a great amount of botanical work was accomplished. He arranged with collectors for the supply of plants from various parts of the country; he got the Government interested in the native flora, so that official papers were issued giving instructions for collecting and soliciting specimens; and Harvey himself devoted so much time to his hobby that he suggests that his title should be Her Majesty's Pleasurer-General, instead of Treasurer-General. Every month brought its quota of undescribed plants. "Almost every small package of specimens received from the Natal, or the Transvaal district," he writes[112], "contains not only new species, but new genera; and some of the latter are of so marked and isolated a character, as to lead us to infer in the same region the existence of unknown types that may better connect them with Genera or Orders already known." To produce system in this chaos he compiled and published his Genera of South African Plants (1838), the forerunner of the larger works which constitute his principal memorial in the domain of Phanerogamic Botany. But the uncongenial climate and the intense application were too great a strain on his health and he reached Europe in 1842, prostrated in both body and mind.
Nevertheless, the final year of his residence in Africa saw the production of the first of the series of works on seaweeds by which his name will ever be best known. His Manual of British Algae was issued by the Ray Society in 1841, its Introduction dated at Cape Town, October 1840—a modest octavo volume, characterized by the thoroughness which runs through all his work.
A period of convalescence and apathy followed his return, in which he wandered about Ireland, doing some desultory botanizing; after which he settled in his old home at Limerick, and again took up the uncongenial duties connected with the family business.
But soon a new prospect opened out. The retirement of William Allman left vacant the Chair of Botany in Dublin University. Harvey had little hesitation in applying for the post, to which, he points out to a friend, "a moderate salary and comfortable College-rooms are attached. It is an old bachelor place," he writes, "and would in many ways suit me very well. The only thing on the face of it disagreeable is the lecturing, but I don't think I should mind that much, as it is lawful to have the subjects for the class written down." Harvey's candidature was viewed favourably by the University authorities, but a difficulty arose, inasmuch as the School of Physic Act prescribed that the Professor of Botany should hold a medical degree, or the licence of the College of Physicians. To render him eligible, the degree of M.D. was at once conferred on Harvey honoris causa, but after a good deal of discussion this solution of the question was held to be inadmissible, and George James Allman was appointed to the vacant chair. Harvey, however, obtained the smaller appointment of Keeper of the University Herbarium, which had fallen vacant at about the same time owing to the death of Dr Thomas Coulter, the botanical explorer of Central Mexico and California.
Harvey now at last found himself in a congenial post, with a fair amount of leisure, and facilities for scientific work. He presented his herbarium of over 10,000 species to the University, which already possessed Coulter's extensive American collections. "I am as busy as a bee these times," he writes. "I rise at 5 a.m. or before it, and work till breakfast-time (half-past eight) at the 'Antarctic Algae[113].' Directly after breakfast I start for the College, and do not leave it till five o'clock in the evening. Again at plants till dusk. I am writing on the 'Antarctic Algae,' and arranging the Herbarium, and have been working at Coulter's Mexican and Californian plants." College vacations were now usually spent at Kew, staying with his best friend Sir William Hooker, and working hard in the Herbarium. On the way home from the first of these vacations, he went to Torquay, to spend some time with his old correspondent, Mrs Griffiths. They went out boating, he and the good lady of seventy-six years; and together they visited the only British habitat of Gigartina Teedii, six miles away, and gathered that coveted sea-weed in the spot where Mrs Griffiths had discovered it in 1811, the year in which Harvey was born.
Another very rare alga which he received about this time, to his great delight, was Thuretia quercifolia from Australia, one of the most remarkable of sea-weeds, bearing oakleaf-shaped red fronds, formed of a beautiful lace-like double network with regular hexagonal openings, which he was himself destined to collect in quantity some years later at Port Phillip, and to figure in his Phycologia Australica[114].
The circumstances under which this plant was found must have made Harvey's mouth water.