Radcliffe-Smith, A. Three-language List of Botanical Name Components. Kew: Royal Botanic Gardens, 1998

Radice, Betty Who's Who in the Ancient World. London: Penguin Group, 1973

Randhawa, M. S. Flowering Trees. New Delhi: National Book Trust, 1965

Rau, M.A. Fascicles of Flora of India – Fascicle 1 – Coriariaceae, Paeoniaceae. New Delhi, India: National Book Trust, 1978

Ray, Elizabeth (Editor) The Best of Eliza Acton. Harmondsworth, Middlesex: Penguin Books Ltd., 1968

Rayner, FRHS, J.F. A Standard Catalogue of English Names of our Wild Flowers – to which are added The Ferns and their Allies. Southampton: H.M. Gilbert and Son, ND

Reader's Digest Encyclopaedia of Garden Plants and Flowers (Hay, Roy - Consultant Editor). London: Reader's Digest, 1978

Redouté, P.J. Redouté’s Roses. Ware, Hartfordshire: Wordsworth Editions Ltd., 1998

Rehder, Alfred Manual of Cultivated Trees and Shrubs Hardy in North America. Portland, Oregon: Dioscorides Press, 1986

Ribeiro, José Eduardo L da S./Hopkins, Michael J.G./Vicentini, Alberto/Sothers, Cynthia A./Costa, Maria Auxiliadora da S./Brito, Joneide M. de/Souza, Maria Anália D. de/Martins, Lúcia Helena P./Lohmann, Lúcia G./Assunção, Paulo Apóstolo C.L./Pereira, Everaldo da C./Silva, Cosmo Fernandes da/Mesquita, Mariana R./Procópio, Lilian C. Flora da Reserva Ducke (Guia de identificação das plantas vasculares de uma floresta de terra-firme na Amazônia Central). Manaus, Brazil: Instituto Nacional de Pesquisas da Amazônia.(INPA)/Department for International Development (DFID), 1999

Richards, E.C. Our New Zealand Trees and Flowers. Christchurch: Simpson & Williams Limited. 1956

Richter, Walter The Orchid World. London: Studio Vista Ltd., 1965

Rickett, H.W. Wild Flowers of America. New York: Crown Publishers, Inc.,

Rinzler, Carol Ann The Complete Book of Herbs, Spices and Condiments. New York: Facts On File, 1990

Robbins, Maria Polushkin A Gardener’s Bouquet of Quotations. London: Robert Hale Limited, 1994 (English)

Robbins, Wilfred William/Harrington, John Peabody/ Freire-Marreco, Barbara Ethnobotany of the Tewa Indians. Washington: Smithsonian Institution, Bureau of American Ethnobotany, Bulletin 55, 1916

Robertson, S.A. Flowers Plants of Seychelles. Kew: Royal Botanic Gardens, 1989

Robyns, W. Flore du Congo Belge et due Ruanda-Urundi – Spermatophytes – Tableau Analytique des Familles and Volumes 1-10. Bruxelles: L’Institut National pour l’Étude Agronomique du Congo Belge (I.N.É.A.C.), 1958

Rock, Joseph F. The Indigenous Trees of the Hawaiian Islands. Rutland, Vermont: Charles E. Tuttle Company, 1913

Rogers, Jo The Encyclopedia of Food and Nutrition. London: Merehurst Limited, 1990

Root, Waverley Food. New York: Smithmark Publishers, 1996

Ross, J.H. The Flora of Natal. Pretoria: Botanical Research Institute, Department of Agricultural Technical Services, Republic of South Africa, 1972

Rothery, Guy Cadogan Concise Encyclopedia of Heraldry. London: Bracken Books, 1985

Rowley, Gordon D. Name That Succulent. Cheltenham: Stanley Thornes (Publishers) Ltd., 1980

Royal Botanic Gardens, Kew (1999). Survey of Economic Plants for Arid and Semi-Arid Lands (SEPASAL) database. Published on the Internet; http://www.rbgkew.org.uk/ceb/sepasal/internet/

Royal Horticultural Society Journal of the Royal Horticultural Society, Vol. XC Part Five. London: RHS, 1965

Royal Horticultural Society Journal of the Royal Horticultural Society, Vol. XC Part Six. London: RHS, 1965

Rydberg, PhD, Per Axel Flora of the Prairies and Plains of Central North America - Volume II of two. New York: Dover Publications, Inc., 1971

Rytz-Miller, Walter Swiss Alpine Flowers. Berne: Hallwag AG., 1949