Noel H. Holmgren

Four new species Of Mexican Castilleja (subgenus Castilleja, Scrophulariaceae) and their relatives

Castilleja subgenusCastilleja in the northern half of Mexico consists of nine species, which are treated here. The subgenus is characterized by a conspicuously colored calyx that is much more deeply cleft in front (abaxially) than in back (adaxially).Castilleja rhizomata,C. linifolia,C. mcvaughii, andC. pterocaulon are described as new, and are illustrated and mapped. The first three are compared toC. patriotica and C.tenuiflora, their closest relatives in the Tenuiflorae group, and the fourth is compared toC. ortegae, with which it constitutes the Ortegae group.Castilleja roei andC. tenuifolia of the Epichroma group are included in order to complete the census of subgenusCastilleja as encountered in the region of the new species. A key to the nine species of subgenusCastilleja from the northern half of Mexico is provided.

New Mentzelias (Loasaceae) from the Intermountain Region of Western United States

Abstract Three new species and two new varieties of Mentzelia belonging to the multistemmed subshrub group of section Bartonia are described. Typical of the group, they are narrow endemics occurring in relatively barren clay soils in the Intermountain Region of interior western U.S. Mentzelia tiehmii and Mentzelia argillicola are from Nevada, Mentzelia memorabalis from northern Arizona, Mentzelia multicaulis variety uintahensis from northeastern Utah and northwestern Colorado, and Mentzelia multicaulis variety flumensevera from central Utah. Communicating Editor: Aaron Liston

Primula cusickiana (Primulaceae) and its varieties

Primula domensis Kass & S. L. Welsh,P. maguirei L. O. Williams, andP. nevadensis N. H. Holmgren are reduced to varietal status underP. cusickiana (A. Gray) A. Gray.

Redefinition of Dodecatheon dentatum (Primulaceae) and rationale for use of varietal rank

The new variety,Dodecatheon dentatum var.utahense, represents a geographic stepping stone betweenD. dentatum var.dentatum of the Pacific Northwest andD. dentatum var.ellisiae of the Southwest. Rationale for using the infraspecific rank of variety includes historical precedence and preponderant usage, convenience of grouping multiple varieties into subspecies, and elimination of subjectivity in grading the magnitude of genetic differences.

GLOSSOPETALON (CROSSOSOMATACEAE) AND A NEW VARIETY OF G. SPINESCENS FROM THE GREAT BASIN, U.S.A.

A new variety from the eastern Great Basin of western U.S.A.,Glossopetalon spinescens var.microphyllum (Crossosomataceae), is described and illustrated, and its relationship within the species is indicated by a key. The nameGlossopetalon A. Gray is used rather than the substituteForsellesia Greene, because there is little chance of confusion with the earlier nameGlossopetalum Schreber, which was illegitimately published and remains obscure.

Subgeneric and sectional names for Intermountain Penstemon (Scrophulariaceae)

Some of the earliest validly published subgeneric and sectional names forPenstemon that have been overlooked or disregarded in recent years are recalled. Lectotype species are designated for sectionsGentianoides G. Don andSaccanthera Benth.

Lectotypifications and new combinations in North American Brassicaceae

Lectotypes are selected for names of five taxa in five genera of Brassicaceae;Boechera, Cardamine, Caulanthus, Cusickiella, Descurainia. Fourteen new combinations are made in six genera:Boechera, Descurainia, Erysimum, Parrya, Physaria, andThelypodium.

A TAXONOMIC STUDY OF JAMESIA (HYDRANGEACEAE)

Jamesia (Hydrangeaceae) is endemic to western North America from the southern Rocky Mountains in southeastern Wyoming and Colorado west across the Great Basin to the southern Sierra Nevada and south through New Mexico and southeastern Arizona to Chihuahua and Nuevo León. Its distinctiveness and Oligocene fossil record suggest that it is an old genus. The genus comprises five geographically distinct taxa that can be grouped into two species. One of these,Jamesia americana, is further divided into four varieties, the second of which is new, and the fourth of which assumes a name older than that in current use:J. americana var.americana, var.zionis, var.macrocalyx, and var.rosea. The second species,J. tetrapetala, is new.

Castilleja (Scrophulariaceae) of Costa Rica and Panama

The mountains of Costa Rica and western Panama constitute a natural floristic region that is inhabited by six species ofCastilleja.Castilleja talamancensis, C. lentii andC. tayloriorum are described as new. The remaining three areC. arvensis,C. irasuensis andC. quirosii. All butC. arvensis are endemic to the area. The six species are keyed, described, illustrated, mapped and documented with literature and specimen citations.

Euphorbia aaron-rossii (Euphorbiaceae), a new species from Marble and Grand Canyons of the Colorado River, Arizona

The new species,Euphorbia aaron-rossii from along the Colorado River within the inner gorge of Marble Canyon and Grand Canyon, Coconino Co., Arizona, is described, mapped, and illustrated. Scanning electron micrographs of the seed coat are included. It clearly belongs to subgenusAgaloma sectionTithymalopsis, where it is most closely related toE. wrightii.