''Ceanothus prostratus'' is a species of shrub in the family Rhamnaceae. Common names include prostrate ceanothus, pinemat, and mahala mat. It is native to the

Pacific Northwest The Pacific Northwest (sometimes Cascadia, or simply abbreviated as PNW) is a geographic region in western North America bounded by its coastal waters of the Pacific Ocean to the west and, loosely, by the Rocky Mountains to the east. Tho ...

of the United States where it grows in

coniferous forests Conifers are a group of cone-bearing seed plants, a subset of gymnosperms. Scientifically, they make up the division Pinophyta (), also known as Coniferophyta () or Coniferae. The division contains a single extant class, Pinopsida. All exta ...

and open plateaus.

Description

''Ceanothus prostratus'' is a decumbent (or "mat-forming") shrub, generally less than 0.3 meters tall and spreading laterally to up to 3 meters. Its

evergreen In botany, an evergreen is a plant which has foliage that remains green and functional through more than one growing season. This also pertains to plants that retain their foliage only in warm climates, and contrasts with deciduous plants, whic ...

leaves are oppositely arranged and generally oval in shape with 3-9 sharp teeth along the margins. The

inflorescence An inflorescence is a group or cluster of flowers arranged on a Plant stem, stem that is composed of a main branch or a complicated arrangement of branches. Morphology (biology), Morphologically, it is the modified part of the shoot of sperma ...

umbel In botany, an umbel is an inflorescence that consists of a number of short flower stalks (called pedicels) that spread from a common point, somewhat like umbrella ribs. The word was coined in botanical usage in the 1590s, from Latin ''umbella'' "p ...

-like, with flowers of blue, purple, or lavender that bloom between April and June. Its fruit is small and rounded with horned lobes. Ceanothus prostratus mat

Habitat

''Ceanothus prostratus'' grows in the understory of mixed conifer forests, from foothills to subalpine areas. It also inhabits open flats and ridges in areas of low chaparral as well as dry interior forest ecosystems. It can be found from elevations ranging between 270–2700 meters above sea level.

Distribution

''Ceanothus prostratus'' is found throughout the

, ranging through

Washington Washington commonly refers to: * Washington (state), United States * Washington, D.C., the capital of the United States ** A metonym for the federal government of the United States ** Washington metropolitan area, the metropolitan area centered o ...

Oregon Oregon () is a state in the Pacific Northwest region of the Western United States. The Columbia River delineates much of Oregon's northern boundary with Washington, while the Snake River delineates much of its eastern boundary with Idaho. T ...

, western

Idaho Idaho ( ) is a state in the Pacific Northwest region of the Western United States. To the north, it shares a small portion of the Canada–United States border with the province of British Columbia. It borders the states of Montana and Wyomi ...

, western

Nevada Nevada ( ; ) is a state in the Western region of the United States. It is bordered by Oregon to the northwest, Idaho to the northeast, California to the west, Arizona to the southeast, and Utah to the east. Nevada is the 7th-most extensive, ...

, and south into northern

California California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the m ...

. The southern extent of its natural range is the central Sierra Nevada mountains. Given its elevational range, this plant is also native to many of the other mountain ranges of the

, including the Klamaths, Siskiyous, Cascades, and

Warner Mountains The Warner Mountains are an -long mountain range running north–south through northeastern California and extending into southern Oregon in the United States. The range lies within the northwestern corner of the Basin and Range Province, exte ...

Ecology

''Ceanothus prostratus'' is part of the subgenus ''Cerastes'', a clade of ''Ceanothus'' that is generally characterized by traits like opposite leaves, persistent corky

stipule In botany, a stipule is an outgrowth typically borne on both sides (sometimes on just one side) of the base of a leafstalk (the petiole). Stipules are considered part of the anatomy of the leaf of a typical flowering plant, although in many speci ...

s, and horned fruits (hence the name "''

Cerastes The cerastes (Greek: κεράστης, transliteration: ''kerastēs'', meaning "having horns"Pliocene The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58Coast Ranges The Pacific Coast Ranges (officially gazetted as the Pacific Mountain System in the United States) are the series of mountain ranges that stretch along the West Coast of North America from Alaska south to Northern and Central Mexico. Although th ...

to create new and diverse habitats. The closest relatives of ''C. prostratus'' within the subgenus ''Cerastes'' are '' Ceanothus pinetorum'' and '' Ceanothus purpureus'', based on a

phylogeny A phylogenetic tree (also phylogeny or evolutionary tree Felsenstein J. (2004). ''Inferring Phylogenies'' Sinauer Associates: Sunderland, MA.) is a branching diagram or a tree showing the evolutionary relationships among various biological spe ...

produced in a 2011 paper. ''Ceanothus prostratus'' is a common

nitrogen-fixing Nitrogen fixation is a chemical process by which molecular nitrogen (), with a strong triple covalent bond, in the air is converted into ammonia () or related nitrogenous compounds, typically in soil or aquatic systems but also in industry. Atm ...

shrub, often found with '' Purshia tridentata''. Together, their combined nitrogen additions to the soil of their habitats may account for 10-60% of annual nitrogen input in those ecosystems. It is also one of only two plants (along with Ceanothus diversifolius) known to be a host for the

parasitic plant A parasitic plant is a plant that derives some or all of its nutritional requirements from another living plant. They make up about 1% of angiosperms and are found in almost every biome. All parasitic plants develop a specialized organ called the ...

Cuscuta ''Cuscuta'' (), commonly known as dodder or amarbel, is a genus of over 201 species of yellow, orange, or red (rarely green) parasitic plants. Formerly treated as the only genus in the family Cuscutaceae, it now is accepted as belonging in the ...

jepsonii'', a

dodder ''Cuscuta'' (), commonly known as dodder or amarbel, is a genus of over 201 species of yellow, orange, or red (rarely green) parasitic plants. Formerly treated as the only genus in the family Cuscutaceae, it now is accepted as belonging in the ...

which until recently was thought to be extinct but could still be surviving and parasitizing ''C. prostratus'' in northern California. ''Ceanothus prostratus'' is one of many plants in the region that colonize logged areas, forming brushfields in the wake of timber harvests when more light reaches the ground. ''Ceanothus prostratus'' is present in plant communities alongside species such as ''

Abies magnifica ''Abies magnifica'', the red fir or silvertip fir, is a western North American fir, native to the mountains of southwest Oregon and California in the United States. It is a high-elevation tree, typically occurring at elevation, though only rare ...

'', '' Arctostaphylos patula'', '' Arctostaphylos nevadensis'', ''

Pinus albicaulis ''Pinus albicaulis'', known by the common names whitebark pine, white bark pine, white pine, pitch pine, scrub pine, and creeping pine, is a conifer tree native to the mountains of the western United States and Canada, specifically subalpine ...

'', ''

Pinus contorta ''Pinus contorta'', with the common names lodgepole pine and shore pine, and also known as twisted pine, and contorta pine, is a common tree in western North America. It is common near the ocean shore and in dry montane forests to the subalpine ...

'', ''

Pinus Jeffreyi ''Pinus jeffreyi'', also known as Jeffrey pine, Jeffrey's pine, yellow pine and black pine, is a North American pine tree. It is mainly found in California, but also in the westernmost part of Nevada, southwestern Oregon, and northern Baja Califo ...

'', '' Pinus ponderosa'', ''

Quercus vaccinifolia ''Quercus vacciniifolia'' (sometimes spelled ''Q. vaccinifolia''), the huckleberry oak, is a member of the ''Protobalanus'' section of genus ''Quercus''. It has evergreen foliage, short styles, very bitter acorns that mature in 18 months, and a ...

'', and ''

Tsuga mertensiana ''Tsuga mertensiana'', known as mountain hemlock, is a species of hemlock native to the west coast of North America, found between Southcentral Alaska and south-central California. Description ''Tsuga mertensiana'' is a large evergreen conifer ...

''.

Varieties

There are two varieties of ''Ceanothus prostratus''. ''C. prostratus'' var. ''occidentalis'' (McMinn) occurs in the

Coast Ranges The Pacific Coast Ranges (officially gazetted as the Pacific Mountain System in the United States) are the series of mountain ranges that stretch along the West Coast of North America from Alaska south to Northern and Central Mexico. Although th ...

and

Klamath Mountains The Klamath Mountains are a rugged and lightly populated mountain range in northwestern California and southwestern Oregon in the western United States. As a mountain system within both the greater Pacific Coast Ranges and the California Coast ...

of northern California, ranging in elevation from 270–1400 m. It forms as more of a low mound than a mat, exhibits a leaf blade folded lengthwise, and has fruit with spreading horns. ''C. prostratus'' var. ''prostratus'' is the more widespread of the two subspecies, covering the majority of the range of ''C. prostratus''. It ranges in elevation from 800–2700 m throughout the

, High Cascades, High Sierra Nevada, and the

Modoc Plateau __NOTOC__ The Modoc Plateau lies in the northeast corner of California as well as parts of Oregon and Nevada. Nearly of the Modoc National Forest are on the plateau between the Medicine Lake Highlands in the west and the Warner Mountains in the ...

. ''C. prostratus var. prostratus'' forms as a mat, has a generally unfolded leaf, and produces fruit with erect horns.

References

External links

Jepson Manual TreatmentUSDA Plants ProfilePhoto gallery
{{Taxonbar, from=Q5055735 prostratus Flora of California Flora of Idaho Flora of Montana Flora of Nevada Flora of Oregon Flora of Washington (state) Flora of the Cascade Range Flora of the Klamath Mountains Flora of the Sierra Nevada (United States) Flora without expected TNC conservation status