''Symphyotrichum ascendens'' (formerly ''Aster ascendens'') is a species of flowering plant in the family Asteraceae known by the common names western aster, long-leaved aster, and Rocky Mountain aster. Blooming July–September, it is native to western North America and can be found at elevations of in several habitats.

Description

''Symphyotrichum ascendens'' is a rhizomatous, perennial, and herbaceous plant growing a branching, erect

stem Stem or STEM may refer to: Plant structures * Plant stem, a plant's aboveground axis, made of vascular tissue, off which leaves and flowers hang * Stipe (botany), a stalk to support some other structure * Stipe (mycology), the stem of a mushro ...

to heights between . Leaves are widely lance-shaped to oblong and pointed, the largest ones near the base of the stem reaching up to long. The stem and leaves are roughly hairy in places. The inflorescence is an array of many

flower heads A pseudanthium (Greek for "false flower"; ) is an inflorescence that resembles a flower. The word is sometimes used for other structures that are neither a true flower nor a true inflorescence. Examples of pseudanthia include flower heads, compos ...

with many narrow violet to nearly white ray florets around a center of golden disc florets that open July–September. The fruit is a hairy cypsela with a long pappus. ''S. ascendens'' is similar to ''

Symphyotrichum chilense ''Symphyotrichum chilense'' (formerly ''Aster chilensis'') is a species of flowering plant in the family Asteraceae known by the common names Pacific aster and common California aster. It is native to the west coast of North America from Briti ...

'', which has smaller flower heads.

Chromosomes

''Symphyotrichum ascendens'' has a chromosome base number of ''x'' = 13. There are

diploid Ploidy () is the number of complete sets of chromosomes in a cell, and hence the number of possible alleles for autosomal and pseudoautosomal genes. Sets of chromosomes refer to the number of maternal and paternal chromosome copies, respectively ...

individuals (''2n'' = 26) which occur in the western portion of its range, and tetraploid ones (''2n'' = 52) found eastward.

Taxonomy

''S. ascendens'' is a member of the genus ''

Symphyotrichum ''Symphyotrichum'' () is a genus of over 100 species and naturally occurring hybrids of herbaceous annual and perennial plants in the composite family Asteraceae, most which were formerly treated within the genus ''Aster''. The majority are end ...

'', sometimes called American-asters, classified in the

subgenus In biology, a subgenus (plural: subgenera) is a taxonomic rank directly below genus. In the International Code of Zoological Nomenclature, a subgeneric name can be used independently or included in a species name, in parentheses, placed between t ...

''Ascendentes''. Its

basionym In the scientific name of organisms, basionym or basyonym means the original name on which a new name is based; the author citation of the new name should include the authors of the basionym in parentheses. The term "basionym" is used in both botan ...

(original scientific name) is and it has many taxonomic synonyms. Its name with author citations is ''Symphyotrichum ascendens'' . In 1834, English

botanist Botany, also called , plant biology or phytology, is the science of plant life and a branch of biology. A botanist, plant scientist or phytologist is a scientist who specialises in this field. The term "botany" comes from the Ancient Greek wo ...

John Lindley John Lindley FRS (5 February 1799 – 1 November 1865) was an English botanist, gardener and orchidologist. Early years Born in Catton, near Norwich, England, John Lindley was one of four children of George and Mary Lindley. George Lindley w ...

formally described the plant that now is named ''Symphyotrichum ascendens''. This species is

allopolyploid Polyploidy is a condition in which the cells of an organism have more than one pair of ( homologous) chromosomes. Most species whose cells have nuclei (eukaryotes) are diploid, meaning they have two sets of chromosomes, where each set contains ...

, derived from the

hybridization Hybridization (or hybridisation) may refer to: *Hybridization (biology), the process of combining different varieties of organisms to create a hybrid *Orbital hybridization, in chemistry, the mixing of atomic orbitals into new hybrid orbitals *Nu ...

of '' S. spathulatum'' (chromosome base number ''x'' = 8) with '' S. falcatum'' (''x'' = 5), each from a different

, ''Symphyotrichum'' and ''Virgulus'', respectively. This produced a plant with a unique base number of ''x'' = 13, also written ''x₂'' = 13 (8 + 5), and it warranted its own subgenus, ''Ascendentes'', and its own species name. One other species is placed within subgenus ''Ascendentes'': '' S. defoliatum''.

Distribution and habitat

Symphyotrichum (Aster) ascendens (4990187045)

Western aster is native to western North America from British Columbia to Saskatchewan, south to the United States in Montana and North Dakota then south to New Mexico, west to California, north to Washington state, and all states in between. It can be found at elevations of in several habitats including grasslands, sagebrush steppe, and meadows.

Citations

References

* * * * * * * * * * * *

External links

*
BONAP distribution map
Biota of North America Program, 2014 {{Taxonbar, from1=Q7661722, from2=Q38781856 ascendens Flora of Western Canada Flora of the Northwestern United States Flora of the Southwestern United States Flora of North Dakota Flora of New Mexico Flora of the Sierra Nevada (United States) ~ ~ Plants described in 1834 Taxa named by John Lindley