Symphyotrichum ascendens

Symphyotrichum ascendens (formerly Aster ascendens) is a species of flowering plant in the family Asteraceae known by the common names western aster,Template:Sfn long-leaved aster,Template:Sfn and Rocky Mountain aster.Template:Sfn 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 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.Template:Sfn

The inflorescence is an array of many flower heads with many narrow violet to nearly white ray florets around a center of golden disc florets that open July–September.Template:Sfn The fruit is a hairy cypsela with a long pappus.Template:Sfn S. ascendens is similar to Symphyotrichum chilense, which has smaller flower heads.Template:Sfn

Chromosomes

Symphyotrichum ascendens has a chromosome base number of x = 13.Template:Sfn There are diploid individuals (2n = 26) which occur in the western portion of its range, and tetraploid ones (2n = 52) found eastward.Template:Sfn

Taxonomy

S. ascendens is a member of the genus Symphyotrichum, sometimes called American-asters,Template:Sfn classified in the subgenus Ascendentes.Template:Sfn Its basionym (original scientific name) is Aster ascendens Lindl., and it has many taxonomic synonyms. Its name with author citations is Symphyotrichum ascendens (Lindl.) G.L.Nesom.Template:Sfn In 1834, English botanist John Lindley formally described the plant that now is named Symphyotrichum ascendens.Template:Sfn

This species is allopolyploid, derived from the hybridization of S. spathulatum (chromosome base number x = 8) with S. falcatum (x = 5),Template:Sfn each from a different subgenus, Symphyotrichum and Virgulus, respectively.Template:Sfn This produced a plant with a unique base number of x = 13,Template:Sfn also written x₂ = 13 (8 + 5),Template:Sfn and it warranted its own subgenus, Ascendentes, and its own species name. One other species is placed within subgenus Ascendentes: S. defoliatum.Template:Sfn

Distribution and habitat

File:Symphyotrichum (Aster) ascendens (4990187045).jpg

Growing in a field

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.Template:Sfn It can be found at elevations of in several habitats including grasslands, sagebrush steppe, and meadows.Template:Sfn

References

• Template:Cite Jepson eFlora
• Template:Cite eFloras
• Template:Cite BSBI 2007
• Template:Cite IPNI
• Template:Cite POWO
• Template:Cite PLANTS

External links

• Template:CalPhotos
• BONAP distribution map, Biota of North America Program, 2014