Isocoma rusbyi, Rusby's Goldenbush, Southwest Desert Flora

Isocoma rusbyi, Rusby's Goldenbush

Rusby's Goldenbush has Yellow disk florets only; numerous flower heads (20 plus) on tips of stems; fruit a cypsela. Isocoma rusbyi

Rusby's Goldenbush blooms from July or August to November. It prefers elevations from 2,500 to 5,000 feet (762-1,524 m). Isocoma rusbyi

Rusby's Goldenbush leaves are light green; narrowly linear and up to 2 inches (1 cm) in length. Isocoma rusbyi

Rusby's Goldenbush is also call Goldenbush. Isocoma rusbyi

Rusby's Goldenbush habitat preferences are lower and upper deserts, pinyon-juniper, chaparral vegetation; Creosote Bush (Larrea) communities, washes, rocky, sandy and gravelly areas. Isocoma rusbyi

Rusby's Goldenbush or Goldenbush is a woody subshrub that has smooth stems (without surface ornamentation) that are light colored. Isocoma rusbyi

Scientific Name: Isocoma rusbyi
Common Name: Rusby's Goldenbush

Also called: Goldenbush

Family: Asteraceae, Sunflower Family

Synonyms: (Aplopappus drummondii, Haplopappus rusbyi)

Status: Native

Duration: Perennial

Size: Up to 3 feet (1 m)

Growth Form: Subshrub; woody, stems without surface ornamentation, light colored.

Leaves: Light green; narrowly linear; up to 2 inches (1 cm) in length.

Flower Color: Yellow disk florets only; numerous flower heads (20 plus) on tips of stems; fruit a cypsela.

Flowering Season: July or August to November

Elevation: 2,500 to 5,000 feet (762-1,524 m)

Habitat Preferences: Lower and upper deserts, pinyon-juniper, chaparral vegetation; Creosote Bush (Larrea) communities, washes, rocky, sandy and gravelly areas.

Recorded Range: Distribution limited in the United States to the southwestern states of AZ, CO, NM and UT. Found mostly in central and northern AZ and southeast UT, with much smaller populations in southwest CO and northwest NM. Rusby's Goldenbush is also native to northwest Mexico.

North America & US County Distribution Map for Isocoma rusbyi.

North America species range map for Rusby's Goldenbush, Isocoma rusbyi:
North American range map courtesy of Virginia Tech, Dept. of Forest Resources & Environmental Conservation

Click image for full size map

U.S. Weed Information: Unknown
Invasive/Noxious Weed Information: Unknown
Wetland Indicator: Unknown
Threatened/Endangered Information: Unknown

Genus Information: In North America there are 11 species and 11 accepted taxa overall for Isocoma. Worldwide, The Plant List includes 15 accepted species names and a further 44 scientific names of infraspecific rank for Isocoma.

The genus Isocoma was published by Thomas Nuttall, (1786-1859), in 1840.

In the Southwestern United States: Arizona has 5 species of Isocoma, California, Utah and Texas each have 3 species, Nevada has 1 species and New Mexico has 4 species. Data approximate and subject to revision.

Comments: Rusby's Goldenbush is a fall blooming yellow daisy formerly included in the genus Haplopappus called Rabbitbrush and Goldenweed. This species and several others were reclassified to Isocoma and other genera.

In Southwest Desert Flora; also see: Alkali Goldenbush, Isocoma acradenia, Southern Goldenbush, Isocoma pluriflora and Burroweed, Isocoma tenuisecta.

Importance to Wildlife, Birds and Livestock Rusby's Goldenbush, Isocoma rusbyi, is apparently toxic to livestock; the 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 Goldenbush, Isocoma rusbyi, brightly colored flowers and plants attracts butterflies, moths and other insects in search of food, nectar or shelter.

Etymology: The genus “Isocoma” (Isoco'ma:) is from the Greek meaning “an equal hair-tuft,” and referring to the flowers.

The genus Isocoma was published by Thomas Nuttall, (1786-1859), in 1840.

The species epithet “rusbyi” (rus'byi:) is named in honor of Henry Hurd Rusby (1855-1940)

Ethnobotany Unknown