The genus Nolina on the Baja California peninsula has not been critically studied. Most of the taxonomic literature dealing with this group is older or incomplete in nature. Taxonomic problems with this genus arise because it is not easy to make herbarium specimens from plants in the field and the taxa are not well represented in collections. Species in this genus are difficult because they are dioecious, generally have large rosettes with many leaves, leaf margins that often cut skin, and the plants have large inflorescences. On older herbarium specimens, it is common to find only a leaf and an inflorescence fragment, and labels often do not provide taxonomically important information such as the plant's growth habit type. Consequently, distinctive inflorescence characters are usually missing from the specimen or from the label data. It is rare to find a complete specimen collection that includes all of the needed species-relevant data. Decisions for delimiting species in this genus are not easy, and in this case, were based mostly upon their morphological character consistency, geographic distribution, and environmental factors. Five species of Nolina are now registered for the Baja California peninsula: N. beldingii, N. bigelovii, N. interrata, N. palmeri, and the new nomenclatural combination N. brandegeei (Trelease) L. Hem. This paper includes: a species identification key, species taxonomic descriptions, ecological and geographical information, common names, taxonomic discussions of species, and pictures for species recognition of all taxa in the Baja California region.
