Stephanomeria diegensis
Encyclopedia
Stephanomeria diegensis is a species of flowering plant in the aster family
known by the common name San Diego wirelettuce. It is native to the coastal hills and ranges of southern California
and Baja California
, where it grows in many types of open habitat. It evolved as a hybrid of Stephanomeria exigua
and S. virgata
. Furthermore, it is thought to be the result of homoploid hybrid speciation
, which is uncommon. The plant is frequently misidentified as one of its parents, especially if older taxonomic keys
are used. This is an erect annual herb easily exceeding two meters in height. Its slender stem has many spreading branches. The basal leaves are linear to lance-shaped and up to 10 centimeters long. The leaves wither early and are absent for most of the year, giving the plant a twiglike appearance. Leaves on the upper stem are small and reduced. The inflorescence
s are usually clusters of flower head
s located at intervals on the stiff branches. Each head has a cylindrical base lined with phyllaries
. These are often glandular. The head contains several ray florets, each with an elongated tube and a white or pink-tinged ligule measuring around a centimeter long. The fruit is a grooved achene
tipped with a spreading cluster of long, plumelike pappus bristles
.
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 San Diego wirelettuce. It is native to the coastal hills and ranges of southern 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...
and Baja California
Baja California
Baja California officially Estado Libre y Soberano de Baja California is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is both the northernmost and westernmost state of Mexico. Before becoming a state in 1953, the area was known as the North...
, where it grows in many types of open habitat. It evolved as a hybrid of Stephanomeria exigua
Stephanomeria exigua
Stephanomeria exigua is a perennial or biennial plant native to the western United States. It is thought to be the parent species of Stephanomeria malheurensis , an endangered plant species found only in southern Oregon...
and S. virgata
Stephanomeria virgata
Stephanomeria virgata, commonly called twiggy wreath plant, virgate wirelettuce, and rod wirelettuce, is a herbaceous annual plant of the sunflower family, Asteraceae. It can be found growing in Western North America, specifically California, but also in Oregon and Nevada and northern Mexico...
. Furthermore, it is thought to be the result of homoploid hybrid speciation
Hybrid speciation
Hybrid speciation is the process wherein hybridization between two different closely related species leads to a distinct phenotype. This phenotype in very rare cases can also be fitter than the parental lineage and as such natural selection may then favor these individuals. Eventually, if...
, which is uncommon. The plant is frequently misidentified as one of its parents, especially if older taxonomic keys
Identification key
In biology, an identification key is a printed or computer-aided device that aids the identification of biological entities, such as plants, animals, fossils, microorganisms, and pollen grains...
are used. This is an erect annual herb easily exceeding two meters in height. Its slender stem has many spreading branches. The basal leaves are linear to lance-shaped and up to 10 centimeters long. The leaves wither early and are absent for most of the year, giving the plant a twiglike appearance. Leaves on the upper stem are small and reduced. 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...
s are usually clusters of flower head
Head (botany)
The capitulum is considered the most derived form of inflorescence. Flower heads found outside Asteraceae show lesser degrees of specialization....
s located at intervals on the stiff branches. Each head has a cylindrical base lined with 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...
. These are often glandular. The head contains several ray florets, each with an elongated tube and a white or pink-tinged ligule measuring around a centimeter long. The fruit is a grooved achene
Achene
An achene is a type of simple dry fruit produced by many species of flowering plants. Achenes are monocarpellate and indehiscent...
tipped with a spreading cluster of long, plumelike pappus bristles
Pappus (flower structure)
The pappus is the modified calyx, the part of an individual disk, ray or ligule floret surrounding the base of the corolla, in flower heads of the plant family Asteraceae. The pappus may be composed of bristles , awns, scales, or may be absent. In some species, the pappus is too small to see...
.