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

Asteraceae The family Asteraceae, alternatively Compositae, consists of over 32,000 known species of flowering plants in over 1,900 genera within the order Asterales. Commonly referred to as the aster, daisy, composite, or sunflower family, Compositae w ...

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

endemic Endemism is the state of a species being found 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 found elsew ...

California California is a U.S. state, state in the Western United States, located along the West Coast of the United States, Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the List of states and territori ...

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 ref ...

in the eastern

San Francisco Bay Area The San Francisco Bay Area, often referred to as simply the Bay Area, is a populous region surrounding the San Francisco, San Pablo, and Suisun Bay estuaries in Northern California. The Bay Area is defined by the Association of Bay Area Go ...

, 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 primarily ...

foothills, and the Tehachapi Mountains. It is also found in the Southern Outer

California Coast Ranges The Coast Ranges of California span from Del Norte or Humboldt County, California, south to Santa Barbara County. The other three coastal California mountain ranges are the Transverse Ranges, Peninsular Ranges and the Klamath Mountains. P ...

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 B ...

.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 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 ...

is a spreading array of branches bearing clusters of

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 ...

. Each flower head is lined with phyllaries 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 dry fruit produced by many species of flowering plants. Achenes are monocarpellate (formed from one carpel) and indehiscent (they do not ope ...

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