Arctostaphylos rainbowensis
Encyclopedia
Arctostaphylos rainbowensis is a species of manzanita
known by the common name Rainbow manzanita. It is endemic to California
, where it is known only from northern San Diego
and southern Riverside Counties
. A specimen was first collected in 1973 and considered to be part of a disjunct population of Arctostaphylos peninsularis, or alternately a hybrid between A. glauca
and Arctostaphylos glandulosa
. Following phenetic analyses
both possibilities were discarded and the plant was described as a new species in 1994. It was named for the community of Rainbow, California
, near where it is most common in the chaparral
of the lower elevation coastal mountains and the only manzanita species throughout most of its range.
This is an erect shrub
reaching a bushlike one meter to a treelike four meters in height. It produces a burl
at its base and is coated in reddish brown, smooth bark. The oval leaves are up to 5 centimeters long and 3.5 wide and are hairless and somewhat waxy in texture. The inflorescence
is a hanging cluster of white urn-shaped flowers each about 6 to 8 millimeters long. The fruit is about a centimeter wide and ripens to a dark purple-brown.
Since the species was first collected its habitat has undergone extensive development, leading to the extirpation
of many of its populations.
Arctostaphylos
Arctostaphylos is a genus of plants comprised by the manzanitas and bearberries. They are shrubs or small trees.There are about 60 species of Arctostaphylos, ranging from ground-hugging arctic, coastal, and mountain species to small trees up to 6 m tall. Most are evergreen , with small oval...
known by the common name Rainbow manzanita. It is endemic to California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
, where it is known only from northern San Diego
San Diego County, California
San Diego County is a large county located in the southwestern corner of the US state of California. Hence, San Diego County is also located in the southwestern corner of the 48 contiguous United States. Its county seat and largest city is San Diego. Its population was about 2,813,835 in the 2000...
and southern Riverside Counties
Riverside County, California
Riverside County is a county in the U.S. state of California. One of 58 California counties, it covers in the southern part of the state, and stretches from Orange County to the Colorado River, which forms the state border with Arizona. The county derives its name from the city of Riverside,...
. A specimen was first collected in 1973 and considered to be part of a disjunct population of Arctostaphylos peninsularis, or alternately a hybrid between A. glauca
Arctostaphylos glauca
Arctostaphylos glauca is a species of manzanita known by the common name bigberry manzanita. It is native to California and Baja California, where it grows in the chaparral and woodland of coastal and inland hills.-Description:...
and Arctostaphylos glandulosa
Arctostaphylos glandulosa
Arctostaphylos glandulosa, with the common name Eastwood's manzanita, is a species of manzanita.-Distribution:This shrub is native to the coastal slopes of western North America from Oregon through California to Baja California.-Description:...
. Following phenetic analyses
Phenetics
In biology, phenetics, also known as taximetrics, is an attempt to classify organisms based on overall similarity, usually in morphology or other observable traits, regardless of their phylogeny or evolutionary relation. It is closely related to numerical taxonomy which is concerned with the use of...
both possibilities were discarded and the plant was described as a new species in 1994. It was named for the community of Rainbow, California
Rainbow, California
Rainbow is a census-designated place in San Diego County, California. The population was 1,832 at the 2010 census, down from 2,026 at the 2000 census.-Geography:Rainbow is located at ....
, near where it is most common in the chaparral
Chaparral
Chaparral is a shrubland or heathland plant community found primarily in the U.S. state of California and in the northern portion of the Baja California peninsula, Mexico...
of the lower elevation coastal mountains and the only manzanita species throughout most of its range.
This is an erect shrub
Shrub
A shrub or bush is distinguished from a tree by its multiple stems and shorter height, usually under 5–6 m tall. A large number of plants may become either shrubs or trees, depending on the growing conditions they experience...
reaching a bushlike one meter to a treelike four meters in height. It produces a burl
Burl
A burl or bur or burr is a tree growth in which the grain has grown in a deformed manner. It is commonly found in the form of a rounded outgrowth on a tree trunk or branch that is filled with small knots from dormant buds.A burl results from a tree undergoing some form of stress. It may be caused...
at its base and is coated in reddish brown, smooth bark. The oval leaves are up to 5 centimeters long and 3.5 wide and are hairless and somewhat waxy in texture. The inflorescence
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. Strictly, it is the part of the shoot of seed plants where flowers are formed and which is accordingly modified...
is a hanging cluster of white urn-shaped flowers each about 6 to 8 millimeters long. The fruit is about a centimeter wide and ripens to a dark purple-brown.
Since the species was first collected its habitat has undergone extensive development, leading to the extirpation
Local extinction
Local extinction, also known as extirpation, is the condition of a species which ceases to exist in the chosen geographic area of study, though it still exists elsewhere...
of many of its populations.