Symphyotrichum ascendens (formerly Aster ascendens) is a species of flowering plant in the family Asteraceae known by the common names western aster,[3]long-leaved aster,[4] and Rocky Mountain aster.[5] Blooming July–September, it is native to western North America and can be found at elevations of 500–3,200 m (1,600–10,500 ft) in several habitats.
Description
Symphyotrichum ascendens is a rhizomatous, perennial, and herbaceous plant growing a branching, erect stem to heights between 20 and 60 centimeters (8 and 24 inches). Leaves are widely lance-shaped to oblong and pointed, the largest ones near the base of the stem reaching up to 15 cm (6 in) long. The stem and leaves are roughly hairy in places.[6]
Symphyotrichum ascendens has a chromosome base number of x = 13.[8] There are diploid individuals (2n = 26) which occur in the western portion of its range, and tetraploid ones (2n = 52) found eastward.[9]
This species is allopolyploid, derived from the hybridization of S. spathulatum (chromosome base number x = 8) with S. falcatum (x = 5),[6] each from a different subgenus, Symphyotrichum and Virgulus, respectively.[12] This produced a plant with a unique base number of x = 13,[8] also written x2 = 13 (8 + 5),[9] and it warranted its own subgenus, Ascendentes, and its own species name. One other species is placed within subgenus Ascendentes: S. defoliatum.[12]
USDA, NRCS (2014). "Symphyotrichum ascendens". The PLANTS Database (plants.usda.gov). Greensboro, North Carolina: National Plant Data Team. Retrieved 22 July 2021.