Observations on pulmonary consumption, or, An essay on the Lichen Islandicus, considered both as an aliment and a medicine in that disorder - University of Glasgow. Library. (J. Smeeton, printer, 1802)

Observations on the structure and economy of plants : to which is added The analogy between the animal and the vegetable kingdom - Hooper, Robert, 1773 -1835 (Sold by Messrs. Fletcher and Co. Messrs. Rivington, St. Paul's Church Yard, 1797)

Observations on the structure and economy of plants : to which is added the analogy between the animal and the vegetable kingdom - Royal College of Physicians of Edinburgh. (sold by Messrs. Fletcher and Co. Messrs. Rivington ; and Messrs. Murray and Highley, London, 1797)

Observations sur la phthisie pulmonaire, ou, Essai sur la mousse d'Islande, considaeraee comme maedicament, et comme aliment, dans cette maladie - University of Glasgow. Library. (Se trouve chez l'auteur, et se vend chez Dulau et Co., Callow, 1802)

Observations sur les plantes - Guettard, Jean Etienne, 1715 -1786 (Durand, 1747)

Oecology of plants : an introduction to the study of plant-communities - Warming, Eugenius, 1841 -1924 (Clarendon Press, 1909)

Oekonomisch-technische Flora der Wetterau - Gärtner, Gottfried, 1754 -1825 (P. H. Guilhauman, 1799)

Oekonomische pflanzenhistorie, nebst dem kern der landwirtschaft garten- und arzneykunst; mit einer vorrede P.F. Gmelin 12 theile (in 4 vol.) - Ehrhart, Balthasar. (1754)

Oesterreichische botanische Zeitschrift (A. Skofitz, 1884)

Oesterreichische botanische Zeitschrift (A. Skofitz)

Oesterreichische botanische Zeitschrift (A. Skofitz, 1891)

Oesterreichische botanische Zeitschrift (A. Skofitz, 1894)

Oesterreichische botanische Zeitschrift (A. Skofitz, 1899)

Oesterreichische botanische Zeitschrift (A. Skofitz, 1903)

Oesterreichische botanische Zeitschrift (A. Skofitz, 1905)

Oesterreichische botanische Zeitschrift (A. Skofitz, 1907)

Oesterreichisches botanisches Wochenblatt ([L.W. Seidel], 1851)

Oesterreichisches botanisches Wochenblatt ([L.W. Seidel], 1852)

Die officinellen Pflanzen der Pharmacopoea Germanica für Pharmaceuten und Mediciner besprochen und durch Originalabbildungen erläutert - Kohl, F. G. (Friedrich Georg), 1855 -1910 (Barth, 1895)

Öfversigt af Finska vetenskaps-societetens förhandlingar - Suomen Tiedeseura (s.n.], 1897)

Öfversigt af Kongl. Vetenskaps-akademiens forhandlingar - Kungl. Svenska vetenskapsakademien. (P. A. Norstedt & Söner, 1857)

Öfversigt af Kongl. Vetenskaps-akademiens forhandlingar - Kungl. Svenska vetenskapsakademien. (P. A. Norstedt & Söner, 1858)

Öfversigt af Kongl. Vetenskaps-akademiens forhandlingar - Kungl. Svenska vetenskapsakademien. (P. A. Norstedt & Söner, 1861)

Öfversigt af Kongl. Vetenskaps-akademiens forhandlingar - Kungl. Svenska vetenskapsakademien. (P. A. Norstedt & Söner, 1865)

Omnium stirpium sciagraphia et icones : quibus plantarum et radicum tum in hortis cultarum, tum in vrbium fossis & muris, pratis, aruis, montibus, collibus, nemoralibus, fluviis, riguis & littoralibus, villis & pagis, spontè provenientium, nomina, figura, natura, natales, synonyma, vsus & virtutes, docentur : cum doctissimorum scriptorum circa eas consensu & dissensu - Chabrey, Dominique, 1610 -1669 (Sumptibus Samuelis de Tournes, 1678)

On the popular names of British plants, being an explanation of the origin and meaning of the names of our indigenous and most commonly cultivated species - Prior, R. C. Alexander (Richard Chandler Alexander), 1809 -1902 (Williams & Norgate, 1863)

On the popular names of British plants, being an explanation of the origin and meaning of the names of our indigenous and most commonly cultivated species - Prior, R. C. Alexander (Richard Chandler Alexander), 1809 -1902 (Williams and Norgate, 1870)

One thousand objects for the microscope - Cooke, M. C. (Mordecai Cubitt), 1825 -1914 (F. Warne, 1869)

One thousand objects for the microscope - Cooke, M. C. (Mordecai Cubitt), 1825 -1914 (Frederick Warne, 1869)

Opuscula philolichenum (J. Lendemer, 2011)

Opuscula philolichenum (J. Lendemer, 2012)

Opuscula philolichenum (J. Lendemer, 2016)

Opuscula philolichenum (J. Lendemer, 2018)

Opuscula philolichenum (J. Lendemer, 2020)

The Ottawa naturalist - Ottawa Field-Naturalists' Club (Ottawa Field-Naturalists' Club, 1906)

Ouresiphoitēs Helveticus, sive, Itinera per Helvetiae Alpinas regiones facta annis MDCCII, MDCCIII, MDCCIV, MDCCV, MDCCVI, MDCCVII, MDCCIX, MDCCX, MDCCXI : plurimis tabulis aeneis illustrata - Scheuchzer, Johann Jakob, 1672 -1733 (Typis ac sumptibus Petri Vander Aa, 1723)

Outlines of British fungology; containing characters of above a thousand species of Fungi, and a complete list of all that have been described as natives of the British Isles - Berkeley, M. J. (Miles Joseph), 1803 -1889 (L. Reeve, 1860)

Outlines of medical botany :comprising vegetable anatomy and physiology...and a glossary of terms - Reid, Hugo. (Maclachlan, Stewart & Co, 1896)

Palaeontographica (Theodor Fischer, 1859)

Papers and proceedings of the Royal Society of Tasmania - Royal Society of Tasmania. (The Society, 1918)

Parte práctica de botánica del caballero Cárlos Linneo, que comprehende las clases, órdenes, géneros, especies y variedades de las plantas, con sus caracteres genéricos y especificos, sinónimos mas selectos, nombres triviales, lugares donde nacen, y propriedades - Linné, Carl von, 1707 -1778 (En la Imprenta Real, 1784)

Paxton's Botanical dictionary; comprising the names, history, and culture of all plants known in Britain; with a full explanation of technical terms. New ed. including all the new plants up to the present year - Paxton, Joseph, Sir, 1803 -1865 (Bradbury, Evans, & co, 1868)

Personal narrative of travels to the equinoctial regions of the New continent during the years 1799-1804 - Humboldt, Alexander von, 1769 -1859 (G. Bell, 1877)

Personal narrative of travels to the equinoctial regions of America, during the year 1799-1804 - Humboldt, Alexander von, 1769 -1859 (Bohn, 1852)

Personal narrative of travels to the equinoctial regions of America during the years 1799 - 1804 - Humboldt, Alexander von, 1769 -1859 (George Routledge, 1895)