Vascular plants of the high Sierra San Pedro Mártir, Baja California, Mexico: an annotated checklist.

Abstract

The Sierra San Pedro Mártir (SSPM) is the highest mountain range in Baja California, Mexico, the summit of Picacho del Diablo peak attaining 3095 meters. An annotated checklist describes the vascular flora of the SSPM high country, defined here as above 1800 m. It comprises almost 500 species in 251 genera and 78 families. The high country is dominated by coniferous forest species known from montane California and Arizona whose southern ranges terminate in the SSPM. The annotated checklist identifies 453 species in 236 genera as indigenous, of which 23 species and one variety are endemic to the SSPM. Over 30 species are unreported from Alta California but occur in regions northeast of Baja California. The climate, vegetation and biogeography of the range are described. Botanical explorations to the area since 1893 are outlined with reference to collectors, their collections, and herbaria where specimens are housed. For each species, the checklist cites one to several collections, months in flower, and known distribution ranges. Asteraceae is the most speciose of the twelve largest families, and Juncus contributes the most indigenous species, followed by Carex and Muhlenbergia. Listed separately are species from chaparral or desert scrub just below the 1800 m limit that are thought to extend into the high country but for which no records exist at this time.