Growth Form:Shrub or subshrub; plants upright (erect); multiple woody stems.
Leaves: Green, dark green or grayish-green; leaves arranged alternately along stems; leaves narrowly linear; gland dotted but not resinous; deeply divided, pinnately lobed; dried older leaves persist at bloom.
Flower Color: Yellow; small, floral heads with diskflorets only; dense clusters on tips of long flowering stalks (inflorescence); old flowers turn brown and persist on plant; fruit is a cypsela.
Flowering Season: August to October
Elevation: 2,000 to 5,500 feet (610-1,676 m)
Habitat Preferences: Wide variety of habitats, lower and upper Sonoran deserts, sunny open areas, dry desert washes, mesas, roadsides and other disturbed areas.
Recorded Range: In the United States, Burroweed is relatively rare where it is found only in central and southern Arizona and southeastern and northwest New Mexico. Burroweed is also native to northwest Mexico.
North America species range map for Burroweed, Isocoma tenuisecta:
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 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.
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: Burroweed is poisonous to mammals, including cattle, which can transfer the poison to humans through milk. Burroweed is common in Arizona and one of many yellow fall blooming subshrubs in the state originally belonging to the large genus Haplopappus. After more review species were moved to Isocoma, Ericameria and other genera.
Burroweed is similar in appearance to the closely related Alkali Goldenbush, Isocoma acradenia whose leaves are linear and not pinnately lobed.
Burroweed, Isocoma tenuisecta, is poisonous to livestock including cattle and sheep and its presence is considered an indicator of overgrazed rangelands. 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
Burroweed, Isocoma tenuisecta, brightly colored flowers readily attracts insects and 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.
