Figure 4 - uploaded by Robert H. Webb
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As part of a larger project inspired by Gentry (1978), we have been mapping the distribution of agaves on the Baja California peninsula. Of the 26 Agave taxa known from the Méxican states of Baja California and Baja California Sur, 24 are endemic to this peninsula or nearby islands (Gentry 1982, Webb & Salazar-Ceseña 2011), with only a few other me...
Citations
... To improve distribution maps, we used both direct observations from a large database begun by Turner et al. (1995) and continued at higher spatial resolution (Webb et al. 2014). We also include information from databases of herbarium specimens held in the United States and México that contained reliable geographical information and add two recently described endemic species (Webb et al. 2011, Webb & Starr 2014b. ...
... Agave pringlei versus Agave moranii in the Sierra Juarez). Webb & Starr (2014a) discuss problems with Agave gigantensis in this context; Webb & Starr (2014b) sorted out the distribution of three species on the Vizcaíno Peninsula and its nearby islands. ...
... The species in section Intermediae have similar vegetative characteristics to those within Deserticolae except they have shorter, cylindrical, and relatively broad inflorescences and that deep flower tube. With the addition of the recently described A. azurea (Webb & Starr 2014b), we found it necessary to create section Intermediae to set apart these two species, which in our opinion form a bridge between the Deserticolae and the Umbelliflorae (Webb & Starr 2014b). The name Intermediae was chosen to reflect that intermediate position. ...
In 1978, Howard Scott Gentry published his second monograph on the genus Agave focusing on the plants of the peninsula of Baja California, México, and the related species in the group Deserticolae in the US and Sonora. We revisit Gentry's work with an emphasis on revising the genus and its taxonomic arrangement and including several recently described species from this Mexican peninsula known for its high plant endemism. A total of 23 Agave taxa occur on the peninsula, 22 of which are endemic. We change Gentry's treatment of four groups into six sections formally defined to better segregate species based on shared inflorescence characteristics. We eliminate one variety, revert one variety to species status, change two species to subspecies or varieties, and reduce one subspecies to a variety. We present high spatial resolution maps of the distribution of these species as well and correct some of the previous identifications of herbarium specimens. Extensive field work suggests that taxonomic problems remain in the Agave sobria complex of the Sierra de la Giganta, where as many as three additional taxa could be described from the array of variation we observed. As well, the distributional overlap of Agave avellanidens and Agave shawii ssp. goldmaniana remains problematic owing to similar vegetative characteristics but greatly differing inflorescences.
... To improve distribution maps, we used both direct observations from a large database begun by Turner et al. (1995) and continued at higher spatial resolution (Webb et al. 2014). We also include information from databases of herbarium specimens held in the United States and México that contained reliable geographical information and add two recently described endemic species (Webb et al. 2011, Webb & Starr 2014b. ...
... Agave pringlei versus Agave moranii in the Sierra Juarez). Webb & Starr (2014a) discuss problems with Agave gigantensis in this context; Webb & Starr (2014b) sorted out the distribution of three species on the Vizcaíno Peninsula and its nearby islands. ...
... The species in section Intermediae have similar vegetative characteristics to those within Deserticolae except they have shorter, cylindrical, and relatively broad inflorescences and that deep flower tube. With the addition of the recently described A. azurea (Webb & Starr 2014b), we found it necessary to create section Intermediae to set apart these two species, which in our opinion form a bridge between the Deserticolae and the Umbelliflorae (Webb & Starr 2014b). The name Intermediae was chosen to reflect that intermediate position. ...