Ortega, María Montserrat Martínez
Ortiz Nuñez, Santiago
Otth, Carl Adolf
Otto, Christoph Friedrich
Ownbey, Francis Marion
Pan, J. T.
Panero, José L.
Panigrahi, Gopinath
Parlatore, Filippo
Patterson, Robert
Pavón Jiménez, José Antonio
Pawłowska, Stanisława Antonina
Pax, Ferdinand Albin
Pelser, Pieter B.
Pennell, Francis Whittier
Perleb, Karl Julius
Persoon, Christiaan Hendrik
Petermann, Wilhelm Ludwig
Pfitzer, Ernst Hugo Heinrich
Philippi, Rodolfo Amando
Picard, Casimir
Pichi-Sermolli, Rodolfo Emilio Giuseppe
Pichon, Marcel
Pilbeam, John William
Pilger, Robert Knud Friedrich
Pissjaukova, V.V.
Planchon, Jules Émile
Plumier, Charles
Plunkett, Gregory M.
Pojarkova, Antonina