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Revision of Bouvardia (Rubiaceae)
Vol 55, Page 1, Date 1968
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Bombacaceae Neotropicae Novae II. New Species of Eriotheca, Hampea and Quararibea
Vol 55, Page 51, Date 1968
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Karyotypes in Relation to Classification and Phylogeny in Claytonia
Vol 55, Page 64, Date 1968
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A New Species of Stelis (Orchidaceae) From Panama
Vol 55, Page 68, Date 1968
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A New Ormosia (Leguminosae) From Peru
Vol 55, Page 79, Date 1968
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Experimental Studies of the Species Concept
Vol 55, Page 179, Date 1968
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Interspecific Relationships in the Polypodium Pectinatum-Plumula Complex
Vol 55, Page 193, Date 1968
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Palynotaxonomic Study of the Phytolaccaceae
Vol 55, Page 294, Date 1968
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Two New Species of Polygala Endemic to Panama
Vol 55, Page 365, Date 1968
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A Revision of the Panamanian Species of Rondeletia (Rubiaceae)
Vol 55, Page 372, Date 1968
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A New Species of Cucurbita from Ecuador
Vol 55, Page 392, Date 1968
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Hedyotis acerosa var. Bigelovii, Comb. Nov. (Rubiaceae)
Vol 55, Page 397, Date 1968