Common Names: Smoothstem Blazingstar, Giant Blazingstar, Evening Star, Stick Leaf
Synonyms: Mentzelia laevicaulis
Taxonomy: Loasaceae (Loasa)
Habit: biennial forb, herb
Size: up to 40 inches
Bloom: May, Jun, Jul, Aug, Sep, Oct, Nov
It grows a weedy-looking, branched stem which may reach a yard in height. The whitish-green stem and its lateral branches bear the occasional triangular sawtoothed leaf. At the tip of each branch blooms a spectacular yellow flower. The star-shaped flower has five narrow, pointed petals with shiny yellow surfaces, each up to 3 inches long. Between the petals are long, thin yellow sepals. The center of the open-faced flower is filled with a great many whiskery yellow stamens. Beneath the petals are long, curling bracts. The flowers of smoothstem blazingstar open at dusk and remain open overnight and into early morning before closing for the afternoon. This species is unusual within its genus of 60 species (nearly all found in the western United States) in having exceptionally large flowers (1½ to 3 inches across) with just 5 yellow petals. Most other species in the genus have 8 to ten or more petals. Hawkmoths are thought to be the primary pollinator.
Distribution: CA, CO, ID, MT, NV, OR, UT, WA, WY
Seen: NV (Mountain Springs Summit)
Habitat: sandy, gravelly or talus-covered slopes of mountain
canyons up to 9000 feet.