From 1869 to 1871 Clarke acted as superintendent of the Calcutta botanical gardens and of cinchona cultivation in Bengal. Returning to his work as an inspector in 1871, Clarke studied in 1872 the Eastern Sundarbans, and in the following year he visited Chittagong. Transferred to Calcutta in 1874, he published there his second work, ‘Commelinaceæ et Cyrtandraceæ Bengalenses,’ and reprinted Roxburgh's ‘Flora Indica’ of 1832 at his own expense. In 1876 he issued a monograph on the Compositæ, to which and to the Gentianaceæ his interest was now directed. In 1875 he was transferred to Darjeeling, and explored the Nipal frontier and British Bhutan. Next year, during a three months' furlough, he visited Kashmir, ascending 17,000 feet in the Karakoram range.
In 1877 Clarke came home on two years' furlough, and presented his herbarium, some 25,000 specimens, representing 5000 species, to the Kew herbarium. Settling down to voluntary botanical work for Sir Joseph Hooker's ‘Flora of British India,’ he was placed on special duty at Kew on the expiration of his leave in 1879, and described, between 1879 and 1883, more than fifty natural orders for the second, third, and fourth volumes of Hooker's work. Returning to India in 1883, Clarke was temporarily appointed director of public instruction in Bengal in 1884, and went in 1885 as inspector to Shillong in Assam, when he studied the flora of the Khasia, Naga, and Manipur hills.
Retiring from India in 1887, Clarke settled at Kew with his brother, Poulter Clarke, to work mainly at Cyperaceæ, on which his authority was soon recognised. In the Linnean Society's ‘Transactions’ he described the Cyperaceæ of the Malay peninsula in 1893–4, those of Mt. Kinabalu in 1894, those of Matto Grosso in 1895, of Madagascar in 1883, those of India in 1884 and 1898, and those of China in 1903–4. In Engler's ‘Jahrbücher’ he described those of Chile; and after his death his descriptions of those of the Philippines appeared in the ‘Philippine Journal of Science,’ and those of the African species in the ‘Bulletin of the French Botanical Society’; whilst 144 plates prepared under his supervision were published, and his monumental monograph of the entire group, although unpublished, was practically completed.
Clarke became a fellow of the Linnean Society in 1867, and of the Geological Society in 1868; from 1880 he served on the council of the former, being a vice-president from 1881 and president from 1894 to 1896. He was elected F.R.S. in 1882, and served on the council from 1888 to 1890. He joined the Geologists' Association in 1897, and constantly engaged in its excursions. In his later years he took to bicycling, riding long distances by day only, without lamp, brake, or bell. He died at Kew, unmarried, of internal inflammation, mainly brought on by excessive bicycling, on 25 Aug. 1906, and was buried at Andover.
To Clarke, Sir Joseph Hooker dedicated in 1880 the Rubiaceous genus Clarkella. His exceptionally versatile interests found expression in ‘Speculations from Political Economy’ (1886); in a ‘Class-book of Geography’ (1889); in an ethnological paper, ‘On the Stone Monuments of the Khasi Hills,’ in the ‘Journal of the Anthropological Institute’ for 1874; in a musico-mathematical note on ‘Equal temperament of the scale’ in ‘Nature’ (1883); and in an unpublished history of England down to the reign of James I. His botanical works, besides those cited and many scattered papers in scientific journals, included monographs on the Commelinaceæ (1881) and on the Cyrtandraceæ (1883) for the continuation of De Candolle's ‘Prodromus,’ and an account of the ferns of British India in the Linnean Society's ‘Transactions’ (1879). He described the Acanthaceæ, Gesneraceæ, and Commelinaceæ for Sir William Thiselton-Dyer's ‘Flora Capensis,’ and for Professor Daniel Oliver's ‘Flora of Tropical Africa’; and several orders for Schmidt's ‘Flora of Koh Chang’ and for Sir George King's ‘Malayan Flora.’
[Journal of Botany, 1906, pp. 370–377, by Colonel Prain and the Rev. W. H. Bliss (with an excellent portrait from a photograph); Kew Bulletin, 1906, pp. 271–281, with full bibliography; Nature, 1906, lxxiv. 495; Proceedings of the Linnean Society, 1906–7, pp. 38–42; Proceedings of the Royal Society, lxxix. series B, pp. xlix–lvi.]
CLARKE, HENRY BUTLER (1863–1904), historian of Spain, born on 9 Nov. 1863 at Marchington, Staffordshire, of which parish his father was incumbent, was elder son of Henry Clarke by his wife Helen, daughter of John Leech of Etwall, near Derby. In 1867 his father became rector of Rokeby. Henry was educated successively at a small school at Whorlton, near Rokeby, at a preparatory school at Richmond, Yorkshire, and finally (1879–83), owing to delicate health, at Jean-de-Luz, where he read with the Basque scholar
