- P. A. Atkins (Firm)
- P. D. (Paul Duménil), 1779-
- P. De Jager & Sons.
- P. E. Cook (Firm)
- P. E. Tichenor & Son.
- P. Emerson (Firm)
- P. Garrett
- P. J. Pentecost (Firm),
- P. L. Rohrer (Firm)
- P. Mann & Co.
- P. Mann & Company.
- P. Vos & Son.
- P., B.
- P., Bullier
- P., L. A.
- P., Lepesmes
- P., W. P.
- P.A. Laeser (Firm)
- P.A. Norstedt & Söner.
- P.B. Mingle & Co.
- P.B. Mingle Co.
- P.C. Baridon & Sons.
- P.D. Berry (Firm)
- P.D. Fulwood (Firm)
- P.D. Fulwood Company (Firm),
- P.E. Tichenor & Son.
- P.H. Foster (Firm)
- P.H. Peyran Co.
- P.J. Hjort & Son.
- P.J. Lynch & Sons.
- P.J. Lynch and Sons.
- P.J. Pentecost (Firm)
- P.L. Bower (Firm)
- P.L. Rohrer & Bro., Inc.
- P.L. Ward (Firm)
- P.L.C. Shepherd & Son, Ltd.
- P.O. Tate Nursery,
- P.T. Yssel-Muiden (Firm)
- Paap, Trudy
- Paar, Ludwig August
- Paarmann, Wilfried
- Paasch, Alexander
- Paasch, Sanitätsrath
- Paasche, Hans, 1881-1920
- Paasivirta, Lauri
- Paaw, Pieter, 1564-1617
- Pabis, Krzysztof
- Pablo Lehmann, A.
- Pablo Parra, Juan
- Pablo Ramírez, Lenin
- Pablo-Cea, José D.
- Pabor, William E. (William Edgar), 1834-
- Pabst, Dr.
- Pabst, Chas E.
- Pabst, G F J
- Pabst, G. (Gustav), 1911
- Pabst, G. C.
- Pabst, L F
- Pac, David F. (David Frank), 1952-
- Pac, Helga Ihsle, 1955-
- Pacatte, Emil.
- Pacaud, Jean-Michel
- Pacaut, M.
- Pacca, Diomedes W
- Paccagnella, Sandra Giselda
- Paccapelo, HA
- Pacciaroni, Adriana
- Pace, Annabella
- Pace, D M
- Pace, David
- Pace, Lula
- Pace, Lynn
- Pace, Marcelo
- Pace, Marcelo Rodrigo
- Pace, Mathew
- Pace, Norman R
- Pace, Richard M
- Pace, Roberto
- Pace, Roberto entomologiste
- Pace, S
- Pace, Stephen D.
- Pacey, A A
- Pachal, Dianne.
- Pachano, Abelardo, 1885-1958
- Pacheco Aguilar, Juan Ramiro
- Pacheco da Silva, Vitor Cezar
- Pacheco Fonseca, Régia
- Pacheco Maldonado, José Constantino
- Pacheco Marino, Suani G
- Pacheco, AJ
- Pacheco, Aldo
- Pacheco, Aldo S.
- Pacheco, Ana Claudia Cotrim
- Pacheco, Andreza C. G.
- Pacheco, Andreza Cecília Gomes
- Pacheco, Ariane Mendonça
- Pacheco, Betania
- Pacheco, C.
- Pacheco, Carlos
- Pacheco, Carlos Eduardo
- Pacheco, Carlos, 1839-1891
- Pacheco, Cristian J.
- Pacheco, Cristiane
- Pacheco, E. B.
- Pacheco, Edson Patto
- Pacheco, Elisa
- Pacheco, F
- Pacheco, FTH.
- Pacheco, G.
- Pacheco, Iliana
- Pacheco, J
- Pacheco, Jos
- Pacheco, José Fernando
- Pacheco, Juan José Hernández
- Pacheco, Leticia
- Pacheco, Liliana
- Pacheco, Luis F.
- Pacheco, M. Andreina
- Pacheco, M. R.
- Pacheco, Marcelle
- Pacheco, Norbert.
- Pacheco, Pablo
- Pacheco, Patricia
- Pacheco, Paula
- Pacheco, R. B.
- Pacheco, Renata
- Pacheco, Rosario
- Pacheco, Rosiley B.
- Pacheco, Rubén Darío
- Pacheco, Sidney
- Pacheco, Silvia
- Pacheco, Susi Missel
- Pachêco, Vanusa Bezerra
- Pacheco, Víctor
- Pacheco-Chaves, Bernald
- Pacheco-Chávez, Rocío
- Pacheco-da-Silva, Vitor C.
- Pacheco-Esquivel, Jessica
- Pacheco-Flores, Cutberto
- Pacheco-Hernández, X. J.
- Pacheco-Rueda Iliana
- Pacheco-Sánchez, Elisa G
- Pacheco-Vega, Juan M
- Pachedjieva, Kalina
- Pachelle, Paulo P. G.
- Paciencia, Gabriel de P.
- Paciencia, Mateus
- Paciencia, Mateus L.B.
- Paciência, Mateus Luis Barradas
- Pacific Alpine Gardens.
- Pacific Coast Entomological Conference University of California) 1909-
- Pacific Coast Entomological Society
- Pacific Coast Nursery.
- Pacific Dahlia Gardens,
- Pacific Expedition (1914-1916).
- Pacific fisheries society.
- Pacific Gardens.
- Pacific Gas and Electric Company.
- Pacific Gas and Electric Company. Dept. of Engineering Research.
- Pacific Grove Nursery.
- Pacific Heights Nursery.
- Pacific Horticultural Correspondence School, Orenco, Ore.
- Pacific Horticultural Correspondence School.
- Pacific Iris Gardens,
- Pacific Landscape Gardeners.
- Pacific Landscape Gardens.
- Pacific Meridian Resources (Firm)
- Pacific Northwest Forest and Range Experiment Station (Portland, Or.)
- Pacific Northwest Forest and Range Experiment Station (Portland, Or.). Forest Utilization Service.
- Pacific Northwest Forest and Range Experiment Station (U.S.).
- Pacific Northwest Forest Experiment Station (Portland, Or.)
- Pacific Northwest Laboratory.
- Pacific Northwest Regional Planning Commission.
- Pacific Northwest Research Station (Corvallis, Or.)
- Pacific Northwest Research Station (Portland, Or.)
- Pacific Northwest Rose Nursery,
- Pacific Nurseries (Colma, Calif.)
- Pacific Nursery Company (Portland, Or.)
- Pacific Nursery Company.
- Pacific Nursery.
- Pacific Oceanographic Group (Canada)
- Pacific Oceanographic Laboratories.
- Pacific Rose Co.
- Pacific Science Association.
- Pacific Science Congress Auckland and Christchurch, N. Z.) 1949-
- Pacific Science Congress Honolulu, Hawaii) 1961-
- Pacific Science Congress Quezon City) 1953-
- Pacific Scientific Institution (Honolulu, Hawaii)
- Pacific Sea Turtle Recovery Team (U.S.)
- Pacific Seabird Group.
- Pacific Seed and Plant Company.
- Pacific Seed Co.
- Pacific Seed Company (Long Beach, Calif.)
- Pacific Seed Company.
- Pacific Seed Growers Co.
- Pacific Southwest Forest and Range Experiment Station (Berkeley, Calif.)
- Pacific States Floral Congress San Francisco) 1901-
- Pacific Sunset Gardens,
- Pacifici, Michela
- Pacífico, Eduardo dos S.
- Pacífico, ES.
- Pacífico, Ricardo
- Pacini, Albert Bonaventure, 1885-
- Pack True-To-Name Nursery,
- Pack, Arthur Newton, 1893-
- Pack, Charles Lathrop, 1857-1937
- Pack, Dean A
- Pack, Frederick J., (Frederick James), 1875-1952
- Pack, George T 1898-1969
- Pack, H
- Pack, H J
- Pack, L E
- Pack, Lloyd C
- Pack, Phillip D.
- Pack, Steven R
- Packard A. S.
- Packard, A. S.
- Packard, A. S. (Alpheus Spring), 1839-1905
- Packard, Charles
- Packard, E. G.
- Packard, Earl L. (Earl Leroy), 1885-
- Packard, Jane M.
- Packard, Patricia L
- Packard, R L
- Packard, Robert L. (Robert Lewis), 1928-
- Packard, Theodore T
- Packard, Winthrop, 1862-1943
- Packauskas, Richard J
- Packer, David J.
- Packer, Db
- Packer, J G
- Packer, Jasmin
- Packer, Jasmin G
- Packer, Jay B.
- Packer, L
- Packer, Laurence
- Packer, W C
- Packer,W C
- Päckert, M
- Packham, G H
- Packham, G H, Stevens, N C
- Packham, Willis A
- Packie, R M
- Packila, Mark L
- Packman, D. J.
- Packova, Gabriela
- Paclt, J
- Paclt, Juraj
- Pacobahyba, Lucilia Dias
- Pacopahyba, Lucília Dias