''Calycadenia oppositifolia'' 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 Butte County western rosinweed. It is native primarily to

Butte County, California Butte County () is a county located in the northern part of the U.S. state of California. In the 2020 census, its population was 211,632. The county seat is Oroville. Butte County comprises the Chico, CA metropolitan statistical area. It is ...

, although a few populations have been found in other parts of the state. It grows in the foothills of the high mountain ranges.

Description

''Calycadenia oppositifolia'' is an annual herb producing an erect, unbranching, hairy stem approaching 30 centimeters (12 inches) in maximum height. The leaves are linear in shape and up to 5 centimeters (2 inches) long, arranged oppositely about the stem. 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

bract In botany, a bract is a modified or specialized leaf, especially one associated with a reproductive structure such as a flower, inflorescence axis or cone scale. Bracts are usually different from foliage leaves. They may be smaller, larger, or of ...

s coated in large

resin In polymer chemistry and materials science, resin is a solid or highly viscous substance of plant or synthetic origin that is typically convertible into polymers. Resins are usually mixtures of organic compounds. This article focuses on natu ...

glands In animals, a gland is a group of cells in an animal's body that synthesizes substances (such as hormones) for release into the bloodstream (endocrine gland) or into cavities inside the body or its outer surface (exocrine gland). Structure De ...

and dense 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 ...

. The hairy, glandular flower head has a center of several

disc floret 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 ...

s surrounded by a few white or reddish triple-lobed

ray florets 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 ...

. Each

ray floret 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 ...

has three lobes at the tip, the middle lobe being shortest. 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 ...

; those developing from the

s have a pappus of scales.Flora of North America, ''Calycadenia oppositifolia'' (Greene) Greene, Fl. Francisc. 4: 423. 1897
/ref>

References

External links

Jepson Manual TreatmentUnited States Department of Agriculture Plants Profilephoto of herbarium specimen at Missouri Botanical Garden, isotype of ''Calycadenia oppositifolia/Hemizonia oppositifolia''Calphotos Photo gallery, University of California
oppositifolia Endemic flora of California Flora of the Sierra Nevada (United States) Natural history of the California chaparral and woodlands Natural history of Butte County, California Plants described in 1897 Taxa named by Edward Lee Greene {{Asteroideae-stub