Stylocline citroleum
Encyclopedia
Stylocline citroleum is a rare species of flowering plant in the aster family
known by the common name oil neststraw.
, where it is known from about 46 occurrences on and around the Elk Hills Oil Field
. The occurrences are patchy and variable in size, and some sources consider them to be part of a single widely spread metapopulation
. The species has been collected from coastal San Diego County
, but any occurrences there are probably now extirpated
.
The plant has been known for over one hundred years, and the type specimen was collected in 1935, but it was not described to science as a distinct species until 1992.
Stylocline citroleum grows in the valley saltbush scrub ecosystem in the sandy flats and clay soils of the San Joaquin Valley
in areas developed into oil field
s, the inspiration for the common
and scientific names of the species. The plant probably evolved as a hybrid of mountain neststraw (Stylocline gnaphaloides)
and California filago (Filago
californica), and it is almost always found growing alongside one or both of its parent species.
bears spherical flower heads
just a few millimeters long with tiny, rough-haired phyllaries
and scaly, woolly florets. It is hard to tell apart from other Stylocline because its defining characteristics are microscopic.
Asteraceae
The Asteraceae or Compositae , is an exceedingly large and widespread family of vascular plants. The group has more than 22,750 currently accepted species, spread across 1620 genera and 12 subfamilies...
known by the common name oil neststraw.
Distribution
It is endemic to Kern County, CaliforniaKern County, California
Spreading across the southern end of the California Central Valley, Kern County is the fifth-largest county by population in California. Its economy is heavily linked to agriculture and to petroleum extraction, and there is a strong aviation and space presence. Politically, it has generally...
, where it is known from about 46 occurrences on and around the Elk Hills Oil Field
Elk Hills Oil Field
The Elk Hills Oil Field is a large oil field in northwestern Kern County, in the Elk Hills of the San Joaquin Valley, California in the United States, about twenty miles west of Bakersfield...
. The occurrences are patchy and variable in size, and some sources consider them to be part of a single widely spread metapopulation
Metapopulation
A metapopulation consists of a group of spatially separated populations of the same species which interact at some level. The term metapopulation was coined by Richard Levins in 1970 to describe a model of population dynamics of insect pests in agricultural fields, but the idea has been most...
. The species has been collected from coastal San Diego County
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...
, but any occurrences there are probably now extirpated
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...
.
The plant has been known for over one hundred years, and the type specimen was collected in 1935, but it was not described to science as a distinct species until 1992.
Stylocline citroleum grows in the valley saltbush scrub ecosystem in the sandy flats and clay soils of the San Joaquin Valley
San Joaquin Valley
The San Joaquin Valley is the area of the Central Valley of California that lies south of the Sacramento – San Joaquin River Delta in Stockton...
in areas developed into oil field
Oil field
An oil field is a region with an abundance of oil wells extracting petroleum from below ground. Because the oil reservoirs typically extend over a large area, possibly several hundred kilometres across, full exploitation entails multiple wells scattered across the area...
s, the inspiration for the common
Common name
A common name of a taxon or organism is a name in general use within a community; it is often contrasted with the scientific name for the same organism...
and scientific names of the species. The plant probably evolved as a hybrid of mountain neststraw (Stylocline gnaphaloides)
Stylocline gnaphaloides
Stylocline gnaphaloides is a species of flowering plant in the aster family known by the common names everlasting neststraw and mountain neststraw...
and California filago (Filago
Filago (genus)
Filago is a genus of plants in the sunflower family. They are sometimes called cottonroses or cudweeds. The name cudweed comes from the fact that they were once used to feed cows that had lost the ability to chew the cud....
californica), and it is almost always found growing alongside one or both of its parent species.
Description
This inconspicuous annual herb produces a grayish, trailing, forking stem no more than 13 centimeters long. The grayish, woolly, pointed leaves are up to 1.4 centimeters long. The inflorescenceInflorescence
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...
bears spherical flower heads
Head (botany)
The capitulum is considered the most derived form of inflorescence. Flower heads found outside Asteraceae show lesser degrees of specialization....
just a few millimeters long with tiny, rough-haired phyllaries
Bract
In botany, a bract is a modified or specialized leaf, especially one associated with a reproductive structure such as a flower, inflorescence axis, or cone scale. Bracts are often different from foliage leaves. They may be smaller, larger, or of a different color, shape, or texture...
and scaly, woolly florets. It is hard to tell apart from other Stylocline because its defining characteristics are microscopic.