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The geographic and morphological parameters of the widespread Arenaria lanuginosa are explored with the conclusion that in North America the species consists of two, largely allopatric, intergrading varieties: A. l. var. saxosa of the southwestern USA and northwestern Mexico, and A. l. var. lanuginosa of southern Mexico and Central America, extending into South America, where it is widespread, the Caribbean Islands, and the southeastern USA (perhaps introduced). Leaf forms occur in both taxa, these often treated as distinct populational taxa. Additionally, the taxonomic reality of A. gypsostrata, related to the A. lanuginosa complex, is reconfirmed.
Pectis is a genus of ±90 xeric adapted New World species. Previous molecular phylogenetic studies showed Pectis closely related to Porophyllum, and one analysis resolved Porophyllum species nested within Pectis. Some Pectis species are known to use C4 photosynthesis. Here we investigate the phylogeny of Pectis and Porophyllum, examine the ploidy levels and geographical distribution of Pectis species in light of its phylogeny, and infer the origin and extent of C4 photosynthesis in both genera. Chloroplast and ITS data from 78 Pectis and 22 Porophyllum species were used to test the monophyly of Pectis and its previously described sections. Carbon isotope data were obtained to infer the photosynthetic pathway of 80 species, and the results mapped on the inferred phylogenies to determine the timing and pattern of evolution of the C4 pathway. The ITS dataset supports a monophyletic Pectis sister to a monophyletic Porophyllum, while the chloroplast dataset places two Porophyllum species sister to a combined Pectis Porophyllum clade. Five well-supported lineages are recovered in Pectis. All Pectis sampled have ∂13C values consistent with C4 photosynthesis, and all Porophyllum species sampled have ∂13C values consistent with C3 photosynthesis. We conclude that Pectis is monophyletic but only two of its recognized sections are monophyletic. Porophyllum is monophyletic but its sections are not. Porophyllum amplexicaule and Pr. scoparium should be treated as members of a new genus. The switch to the C4 pathway in Pectis happened in the late Miocene, probably in north/central Mexico, at or after the divergence of Pectis and Porophyllum. This location and timing is consistent with the evolution of C4 photosynthesis in other North American eudicot lineages, suggesting similar environmental conditions may underlie the switch to C4 photosynthesis.
The naturalized North American distribution of the Old World native, Cynoglossum creticum Mill. (Boraginaceae), is detailed. The species has now been documented from a number of sites in six counties in Arkansas, Missouri, and Texas, as well as from the Mexican states of Coahuila, Nuevo León, and Zacatecas.