''Tetradymia argyraea'' is a species of flowering plant in the aster family known by the common names spineless horsebrush and gray horsebrush. It is native to western North America.

Distribution

The range of ''Tetradymia argyraea'' is primarily east of the

Cascade Range The Cascade Range or Cascades is a major mountain range of western North America, extending from southern British Columbia through Washington and Oregon to Northern California. It includes both non-volcanic mountains, such as the North Cascades, ...

and

Sierra Nevada The Sierra Nevada () is a mountain range in the Western United States, between the Central Valley of California and the Great Basin. The vast majority of the range lies in the state of California, although the Carson Range spur lies primarily ...

of British Columbia to California. It extends eastward to southwest Montana, Wyoming, western Colorado and northwest New Mexico, where it grows in sagebrush scrub, woodlands, forest, scrubby open plains, and other habitat. It occupies a large range of elevations from near sea level to but favors the range of . Tetradymia canescens 7

Description

It is a bushy

shrub A shrub (often also called a bush) is a small-to-medium-sized perennial woody plant. Unlike herbaceous plants, shrubs have persistent woody stems above the ground. Shrubs can be either deciduous or evergreen. They are distinguished from trees ...

tall with multibranched woody or semi-woody stems that grow from taproots. It is coated in woolly fibers with hairless strips at intervals along the branches. It has no spines. The lance-shaped leaves are no more than long and woolly or silver-haired in texture. Longer-lived leaves are alternately arranged along the stem and smaller, shorter-lived leaves occur in clusters near the axils of the primary leaves. The inflorescence bears usually three to six

flower heads A pseudanthium (Greek for "false flower"; ) is an inflorescence that resembles a flower. The word is sometimes used for other structures that are neither a true flower nor a true inflorescence. Examples of pseudanthia include flower heads, compos ...

which are each enveloped in four thick phyllaries coated in white woolly hairs. Each head contains four tubular flowers in shades of pale to bright yellow, each long. Flowers are produced in May through October. The fruit is an

achene An achene (; ), also sometimes called akene and occasionally achenium or achenocarp, is a type of simple dry fruit produced by many species of flowering plants. Achenes are monocarpellate (formed from one carpel) and indehiscent (they do not ope ...

long including its long pappus of bristles. The shrub is wildfire-resistant, resprouting vigorously and increasing in herbage and seed production in seasons following a fire.US Forest Service Fire Ecology
/ref> Fire suppression efforts decrease the abundance of the shrub and frequent burns increase it. The shrub is toxic to sheep, causing photosensitivity, bad wool quality, abortion, and death due to the presence of furanoeremophilanes. It causes a swelling of the head known as bighead disease. Native American groups used this plant for a number of medicinal purposes, including protection from

ghost A ghost is the soul or spirit of a dead person or animal that is believed to be able to appear to the living. In ghostlore, descriptions of ghosts vary widely from an invisible presence to translucent or barely visible wispy shapes, to rea ...

s and witches.Ethnobotany
/ref>

References

External links

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Flora of North AmericaCalPhotos gallery
{{Taxonbar, from=Q7156013 Senecioneae