Genetic structuring of plant populations is strongly influenced by both common ancestry and current patterns of interpopulation genetic exchange. The interaction of these two forces is particularly confounding and hence interesting in plants. This complexity of plant genetic structures is due in part to a diversity of reproductive ecologies affecting genetic exchange and the fact that reproductive barriers are often weak between otherwise morphologically well‐defined species. Phylogeographic methods provide a means of examining the history of genetic exchange among populations, with the potential to distinguish biogeographic patterns of genetic variation caused by gene flow from those caused by common ancestry. With regard to plants, phylogeography will be most useful when applied broadly across the entire spectrum of potential genetic exchange. Although current phylogeographic studies of plants show promise, widespread application of this approach has been hindered by a lack of appropriate molecular variation; this problem is discussed and possible solutions considered.

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A revision of 6 closely related species from the Amazon basin in Colombia, Ecuador and Peru is presented, and 4 new species of Anthurium are published as new: Anthurium ceronii Croat, A. payaminoense Croat & Lingán, A. sydneyi Croat & Lingán and A. whitmorei Croat & Lingán. Two species, A. decurrens Poeppig and A. longispadiceum K. Krause are redescribed because they have been, until recently, totally unknown or misrepresented by other taxa. The species are all members of a new section named Decurrentia, newly named here for the first time. All members of section Decurrentia have in common short internodes, elongated, epunctate leaf blades, and peduncles tending to be weakly or prominently ridged or winged. In addition, several of the species have early-emergent, elongated berries. All species treated here occur in the lowlands of Amazonia and have been confused with one another by botanists for a long time.

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