''Osmadenia'' is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

of flowering plants 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 ...

. It contains the single species ''Osmadenia tenella'', which is known by the common name false rosinweed.

Distribution

''Osmadenia tenella'' is native to the coastal plains and the hills and canyons of the

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 ...

Southern California Southern California (commonly shortened to SoCal) is a geographic and Cultural area, cultural region that generally comprises the southern portion of the U.S. state of California. It includes the Los Angeles metropolitan area, the second most po ...

, and the

Peninsular Ranges The Peninsular Ranges (also called the Lower California province) are a group of mountain ranges that stretch from Southern California to the southern tip of the Baja California peninsula; they are part of the North American Coast Ranges, which ...

in Southern

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 ...

and

Baja California Baja California (; 'Lower California'), officially the Free and Sovereign State of Baja California ( es, Estado Libre y Soberano de Baja California), is a state in Mexico. It is the northernmost and westernmost of the 32 federal entities of Mex ...

.Calflora taxon report, University of California, ''Osmadenia tenella'' Nutt., false rosinweed
/ref> It is an uncommon member of the flora in local

habitat In ecology, the term habitat summarises the array of resources, physical and biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species habitat can be seen as the physical ...

s, such as the coastal sage and chaparral and montane chaparral and woodlands sub-ecoregions.

Description

''Osmadenia tenella'' is a hairy, glandular, aromatic annual herb producing an erect stem approaching 40 centimeters (16 inches) in maximum height with threadlike branches. The linear leaves are alternately arranged, the largest low on the plant measuring up to 5 centimeters. 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 cyme of several

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 head has 3 to 5 three-lobed ray florets which are white or pink-tinged and often have a pink spot, and several narrower

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.Flora of North America: ''Osmadenia tenella''
/ref> 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 arising from

s have

pappi In Asteraceae, the pappus is the modified calyx, the part of an individual floret, that surrounds the base of the corolla tube in flower. It functions as a wind-dispersal mechanism for the seeds. The term is sometimes used for similar s ...

References

External links

*
Jepson Manual Treatment of ''Osmadenia tenella''USDA Plants Profile for ''Osmadenia tenella'' (false rosinweed)''Osmadenia tenella'' — U.C. Photo gallery
{{Taxonbar, from1=Q16185920, from2=Q2005860 Flora of California Flora of Baja California Natural history of the California chaparral and woodlands Natural history of the Peninsular Ranges Natural history of the Transverse Ranges Monotypic Asteraceae genera Plants described in 1841 Madieae