''Tetradymia tetrameres'' is a species of flowering plant in the aster family known by the common name fourpart horsebrush and dune horsebrush. It is native to the

Great Basin The Great Basin is the largest area of contiguous endorheic basin, endorheic watersheds, those with no outlets, in North America. It spans nearly all of Nevada, much of Utah, and portions of California, Idaho, Oregon, Wyoming, and Baja California ...

, where it occurs in western Nevada and just over the border in

Mono County, California Mono County ( ) is a county located in the east central portion of the U.S. state of California. As of the 2020 census, the population was 13,195, making it the fourth-least populous county in California. The county seat is Bridgeport. The coun ...

. It is a plant of dry scrub and

sand dunes A dune is a landform composed of wind- or water-driven sand. It typically takes the form of a mound, ridge, or hill. An area with dunes is called a dune system or a dune complex. A large dune complex is called a dune field, while broad, fl ...

. It is a bushy, woolly

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 ...

with many erect, spineless branches. It is the largest of the horsebrushes, growing up to two meters in height.Mozingo, H. N. (1987).
Shrubs of the Great Basin: A Natural History.
' University of Nevada Press 317-8. The soft, woolly leaves are narrow and threadlike, growing up to 4 centimeters long. Shorter leaves occur in clusters around the primary leaves. The

inflorescence An inflorescence is a group or cluster of flowers arranged on a stem that is composed of a main branch or a complicated arrangement of branches. Morphologically, it is the modified part of the shoot of seed plants where flowers are formed o ...

bears 4 to 6

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 or five woolly

phyllaries In botanical terminology, a phyllary, also known an involucral bract or tegule, is a single bract of the involucre of a composite flower. The involucre is the grouping of bracts together. Phyllaries are reduced leaf-like structures that form one or ...

. Each head contains up to four or five light yellow flowers each around a centimeter long. The fruit is a hairy

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 ...

which may be up to a centimeter long, including its pappus of long bristles.

References

External links

Jepson Manual TreatmentFlora of North America
Senecioneae Flora of California Flora of Nevada Plants described in 1922 Flora without expected TNC conservation status {{Senecioneae-stub