''Holocarpha heermannii'' is a species of flowering plant in the family

Asteraceae Asteraceae () is a large family (biology), family of flowering plants that consists of over 32,000 known species in over 1,900 genera within the Order (biology), order Asterales. The number of species in Asteraceae is rivaled only by the Orchi ...

known by the common name Heermann's tarweed. It is

endemic Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...

California California () is a U.S. state, state in the Western United States that lies on the West Coast of the United States, Pacific Coast. It borders Oregon to the north, Nevada and Arizona to the east, and shares Mexico–United States border, an ...

Distribution

''Holocarpha heermannii'' grows in the hills, mountains, and valleys of the central and southern part of California. It is most common in the

Inner Coast Ranges The Inner Coast Ranges are a long mountain range subsystem of the California Coast Ranges, running generally north–south in western California, from Santa Barbara County north to the Klamath Mountains system. Geography The term ''inner'' is a re ...

in the eastern

San Francisco Bay Area The San Francisco Bay Area, commonly known as the Bay Area, is a List of regions of California, region of California surrounding and including San Francisco Bay, and anchored by the cities of Oakland, San Francisco, and San Jose, California, S ...

, the southern

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 primari ...

foothills, and the

Tehachapi Mountains The Tehachapi Mountains (; Kawaiisu: ''Tihachipia'', meaning "hard climb") are a mountain range in the Transverse Ranges system of California in the Western United States. The range extends for approximately in southern Kern County and northwe ...

. It is also found in the Southern Outer

California Coast Ranges The Coast Ranges of California span from Del Norte County, California, Del Norte or Humboldt County, California, south to Santa Barbara County, California, Santa Barbara County. The other three coastal California mountain ranges are the Trans ...

and western

Transverse Ranges The Transverse Ranges are a group of mountain ranges of Southern California, in the Pacific Coast Ranges physiographic region in North America. The Transverse Ranges begin at the southern end of the California Coast Ranges and lie within Santa Ba ...

.CalFlora taxon report, University of California, ''Holocarpha heermannii'' (E. Greene) Keck, Heermann's tarweed
. accessed 11.14.2013Flora of North America, ''Holocarpha heermannii'' (Greene) D. D. Keck, 1958.
/ref>

Description

''Holocarpha heermannii'' is an annual herb growing mostly erect from to over in height. The stem is densely glandular and coated in short and long hairs. The leaves are up to long near the base of the plant and those along the stem are smaller. The

inflorescence In botany, an inflorescence is a group or cluster of flowers arranged on a plant's Plant stem, stem that is composed of a main branch or a system of branches. An inflorescence is categorized on the basis of the arrangement of flowers on a mai ...

is a spreading array of branches bearing clusters of

flower heads A pseudanthium (; : pseudanthia) 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, composite flowers ...

. Each flower head is lined with

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 o ...

which are coated in large bulbous resin glands. They are hairy and sticky in texture. The head contains many yellow disc florets surrounded by three to 10 golden yellow ray florets. The ray and fertile disc florets produce

achene An achene (; ), also sometimes called akene and occasionally achenium or achenocarp, is a type of simple fruit, simple dry fruits, dry fruit produced by many species of flowering plants. Achenes are monocarpellate (formed from one carpel) and Dehi ...

s of different shapes.

References

External links

Jepson Manual Treatment: ''Holocarpha heermannii''CalFlora Database: ''Holocarpha heermannii'' (Heermann's tarweed)USDA Plants Profile: ''Holocarpha heermannii'' (Heermann's tarweed)''Holocarpha heermannii''— U.C. Photos gallery
Madieae Endemic flora of California Flora of the Sierra Nevada (United States) Natural history of the California chaparral and woodlands Natural history of the California Coast Ranges Natural history of the Transverse Ranges ~ Flora without expected TNC conservation status {{Madieae-stub