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(1) Páléontologie végétale Cryptogames cellulaires et Cryptogames vasculaires (2) Die Oekologie der Pflanzen (3) The Diseases of Tropical Plants (4) Icones Orchidearum Austro-Africanarum Extra-Tropicarum; or, Figures, with Descriptions of Extra-Tropical South African Orchids (5) Index Kewensis Plantarum Phanerogamarum Supplementum Quartum (1906–1910)