Arthur H. Holmgren

Sphaeromeria, a genus closer to Artemisia than to Tanacetum (Asteraceae: Anthemideae)

A new species,Sphaeromeria ruthiae, from Zion National Park, and three new combinations,S. martirensis,S. compacta, andS. potentilloides var.nitrophila, are presented. Morphological and anatomical evidence is used to support the recognition ofSphaeromeria as distinct fromTanacetum.

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.

Three new species from the Great Basin

Allium passeyi from Blue Creek Valley of northern Utah,Geranium toquimense from the Toquima Range of central Nevada, andPrimula capillaris from the Ruby Mountains of northeastern Nevada are described, illustrated, and compared with their relatives. The three species are narrow endemics.

A new species of Townsendia (Asteraceae) from northern Arizona

Townsendia smithii, from northwestern Arizona, is described, illustrated and contrasted with other Arizona species in a key.