Flower Color: Yellow; multiple flower heads (up to 250) in flat-topped arrays; heads with both ray and diskflorets; bract surrounding floral heads typically bell-shaped; fruit a cypsela.
Flowering Season: July and August to September and October
Elevation: 5,000 to 8,000 feet (1,500-2,438 m)
Habitat Preferences: Higher elevations in dry soil, open areas in pinyon juniper communities, roadsides and rocky slopes.
Recorded Range: Rare in the United States, distribution is limited to Arizona and New Mexico. In Arizona Rusby's Rubberweed is found in the northern and northwestern parts of the state and in Gila County. In New Mexico its occurrence is in the southeastern part of the state.
North America species range map for Rusby's Rubberweed, Hymenoxys rusbyi:
North American range map courtesy of Virginia Tech, Dept. of Forest Resources & Environmental Conservation
Click image for full size map
Genus Information: In North America there are 8 species and 24 accepted taxa overall for Hymenoxys. Worldwide, The Plant List includes 26 accepted species names and a further 35 scientific names of infraspecific rank for Hymenoxys.
In the Southwestern United States: Arizona has 12 species of genus, California has 4 species, Nevada and Texas each have 5 species, New Mexico has 10 species and Utah has 7 species. Data approximate and subject to revision.
Comments: Although rare in the United States Rusby’s Rubberweed in locally common where found above 5,000 feet (1,500 m) in Arizona. These photographs were taken of a lone specimen roadside in the Mazatzal Mountains off Highway 87 near Mount Ord, Tonto National Forest, Maricopa County, Arizona.
This species is similar to and may be mistaken for the somewhat smaller Pingue Rubberweed, Hymenoxys richardsonii which is more robust, taller and has more branches as well as a much larger distribution.
Importance to Wildlife, Birds and Livestock
Rusby's Rubberweed, Hymenoxys rusbyi flowers, seeds and plants may be visited by hummingbirds and/or small mammals including rodents in search of food, nectar, shelter and protection through cover.
Beneficial Value to Butterflies, Bees and Insects
Rusby's Rubberweed, Hymenoxys rusbyi, with their brightly colored flowers and plants may be visited by butterflies, moths and other insects in search of nectar, food and shelter.
The genus “Hymenoxys” (Hymenox'ys:) from the Greek hymen, “a membrane,” and oxys, “sharp-pointed, sharp,” and apparently alluding to the pappus.