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

Butte County, California Butte County () is a county located in the northern central 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, California, metropolitan stat ...

, 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 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 ...

bears

bract In botany, a bract is a modified or specialized leaf, associated with a reproductive structure such as a flower, inflorescence axis or cone scale. Bracts are usually different from foliage leaves in size, color, shape or texture. They also lo ...

s coated in large

resin A resin is a solid or highly viscous liquid that can be converted into a polymer. Resins may be biological or synthetic in origin, but are typically harvested from plants. Resins are mixtures of organic compounds, predominantly terpenes. Commo ...

glands A gland is a Cell (biology), cell or an Organ (biology), organ in an animal's body that produces and secretes different substances that the organism needs, either into the bloodstream or into a body cavity or outer surface. A gland may also funct ...

and dense 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 ...

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

disc floret Asteraceae () is a large family of flowering plants that consists of over 32,000 known species in over 1,900 genera within the order Asterales. The number of species in Asteraceae is rivaled only by the Orchidaceae, and which is the larger fa ...

s surrounded by a few white or reddish triple-lobed

ray florets Asteraceae () is a large family of flowering plants that consists of over 32,000 known species in over 1,900 genera within the order Asterales. The number of species in Asteraceae is rivaled only by the Orchidaceae, and which is the larger fa ...

. Each

ray floret Asteraceae () is a large family of flowering plants that consists of over 32,000 known species in over 1,900 genera within the order Asterales. The number of species in Asteraceae is rivaled only by the Orchidaceae, and which is the larger fam ...

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 fruit, simple dry fruits, dry fruit produced by many species of flowering plants. Achenes are monocarpellate (formed from one carpel) and Dehi ...

; 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