''Hemizonella '' is a genus of

North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Car ...

n plants in the tribe Madieae within the family Asteraceae.Flora of North America Vol. 21 Page 296, ''Hemizonella'' (A. Gray) A. Gray
/ref> The only known species is ''Hemizonella minima'' (opposite-leaved tarweed), native to British Columbia, Washington, Oregon, California, Montana, Idaho, NevadaFlann, C (ed) 2009+ Global Compositae Checklist
/ref>Hemizonella bonap The plant grows in many types of forest, scrub, and

chaparral Chaparral ( ) is a shrubland plant community and geographical feature found primarily in the U.S. state of California, in southern Oregon, and in the northern portion of the Baja California Peninsula in Mexico. It is shaped by a Mediterranean c ...

habitats, from mountains to deserts. It is found in the

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 ...

and

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 Mojave Desert. ''Hemizonella minima'' is a small annual herb producing a thin, fuzzy stem up to about in maximum height. The pointed, hairy leaves are no more than long. The inflorescence produces one or more tiny

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 oblong or shaped like

top A spinning top, or simply a top, is a toy with a squat body and a sharp point at the bottom, designed to be spun on its vertical axis, balancing on the tip due to the gyroscopic effect. Once set in motion, a top will usually wobble for a few ...

s on close inspection. Each is a few millimeters wide, enclosed in phyllaries studded with stalked resin glands, and tipped with minute yellowish florets. 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 ...

a few millimeters long with no pappus.

References

Monotypic Asteraceae genera Flora of British Columbia Flora of the Western United States Madieae {{Madieae-stub