''Malacothamnus arcuatus'' is a species of flowering plant in the

mallow family Malvaceae, or the mallows, is a family of flowering plants estimated to contain 244 genera with 4225 known species. Well-known members of economic importance include okra, cotton, cacao and durian. There are also some genera containing familiar o ...

, which has two varieties, one of which is sometimes recognized as the species ''Malacothamnus hallii''.Morse, K. 2023
Malacothamnus Volume 3: A Revised Treatment of the Genus Malacothamnus (Malvaceae) Based on Morphological and Phylogenetic Evidence.
/ref>

Varieties

Two varieties are recognized in ''Malacothamnus arcuatus'': ''Malacothamnus arcuatus'' var. ''arcuatus'' and ''Malacothamnus arcuatus'' var. ''elmeri''. The two varieties are mostly morphologically distinct but intergrade where their geographic ranges meet. These varieties together form a single clade in phylogenetic analyses with some analyses providing evidence supporting two taxa. ''Malacothamnus arcuatus'' var. ''arcuatus'' is distinguished from ''M. arcuatus'' var. ''elmeri'' by having longer calyx bracts and longer stellate trichome rays on the stem.Morse, K. 2023
Malacothamnus Volume 1: A Morphological Assessment of Taxonomic Boundaries in the Genus Malacothamnus (Malvaceae).
/ref>Morse, K. 2023
Malacothamnus Volume 2: A Phylogenetic Assessment of Taxonomic Boundaries in the Genus Malacothamnus (Malvaceae).
/ref> ''Malacothamnus arcuatus'' var. ''arcuatus'' is known by the common names western bewildering bushmallow and arcuate bushmallow. 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 els ...

to the

San Francisco Peninsula The San Francisco Peninsula is a peninsula in the San Francisco Bay Area that separates San Francisco Bay from the Pacific Ocean. On its northern tip is the City and County of San Francisco. Its southern base is Mountain View, south of Palo Alt ...

. ''Malacothamnus arcuatus'' var. ''elmeri'' is known by the common names eastern bewildering bushmallow and Hall’s bushmallow. When treated at the species rank, it is given the name ''M. hallii''. It is endemic to the southern Coastal Ranges of California, primarily in the northern half of the

Diablo Range The Diablo Range is a mountain range in the California Coast Ranges subdivision of the Pacific Coast Ranges in northern California, United States. It stretches from the eastern San Francisco Bay area at its northern end to the Salinas Valley ...

and areas in-between it and the

Santa Cruz Mountains The Santa Cruz Mountains, part of the Pacific Coast Ranges, are a mountain range in central and Northern California, United States. They form a ridge down the San Francisco Peninsula, south of San Francisco. They separate the Pacific Ocean fr ...

References

External links

Identification guide to ''Malacothamnus'' with maps and photosCalphotos image gallery for ''Malacothamnus arcuatus'' var. ''arcuatus''Calphotos image gallery for ''Malacothamnus arcuatus'' var. ''elmeri''
Flora of California Endemic flora of California arcuatus Natural history of Contra Costa County, California Natural history of San Mateo County, California Natural history of Santa Clara County, California Natural history of Santa Cruz County, California Flora without expected TNC conservation status {{Malvoideae-stub