Symphyotrichum spathulatum (formerly Aster spathulatus) is a species of flowering plant in the familyAsteraceaenative to western North America including northwestern Mexico. Commonly known as western mountain aster, it is a perennial, herbaceous plant that may reach 20 to 80 centimeters (8 to 31 inches) tall. Its flowers, which open in July and August, have violet ray florets and yellow disk florets.[5]
Description
Symphyotrichum spathulatum blooms in July and August and is a colony-forming perennial that grows typically 1–5 hairless or mostly hairless stems from a long rhizome. It ranges from 20 to 80 centimeters (8 to 31 inches) in height and has thin, entire leaves with little to no hair that are 5 to 15 centimeters (2 to 6 inches) long. The leaves are linear or elliptical, narrow, and sometimes obovate at the base of the plant. The upper leaves are shorter at 3 to 6 centimeters (1+1⁄8 to 2+3⁄8 inches).[5]
The flower heads grow in corymbiform to paniculiform arrays with little branching. The involucres are 5–10 millimeters (1⁄5–2⁄5 inch) and bell-shaped, and their phyllaries are in 3–5 series. There are 15–40 violet ray florets that are 9–15 millimeters (7⁄20–3⁄5 inch) long and 1–2 millimeters (1⁄20–1⁄10 inch) wide. These surround the flower centers composed of 30–80 (sometimes up to 100) yellow disk florets.[5]
The seeds are brown, hairy cypselae 2.5–3.5 mm (1⁄10–3⁄20 in) long with about 4 nerves and white pappi that are 5–7 millimeters (1⁄5–3⁄10 inch) long.[5]
Chromosomes
Symphyotrichum spathulatum has a base number of x = 8.[6]Diploid, tetraploid, hexaploid, and octaploid cytotypes with respective chromosome counts of 16, 32, 48, and 64 have been reported, depending upon the infraspecies, as follows:
S. spathulatum var. spathulatum: 2n = 2x = 16, 2n = 4x = 32, 2n = 6x = 48, and 2n = 8x = 64[7]
S. spathulatum var. intermedium: 2n = 4x = 32, 2n = 6x = 48, and 2n = 8x = 64[8]
S. spathulatum var. yosemitanum: 2n = 2x = 16, 2n = 4x = 32[9]
Taxonomy
Symphyotrichum spathulatum is one of the species within Symphyotrichumsect.Occidentales.[a][11]S. spathulatum was first formally described by John Lindley in 1834 as Aster spathulatus.[12]
Three varieties of Symphyotrichum spathulatum are recognized, including the autonym:[5]
S. spathulatum var. intermedium is native to British Columbia, California, Idaho, Nevada, Oregon, and Washington state,[3] only occasionally being found in California and Nevada. It grows at 1,200–2,200 m (3,900–7,200 ft) in grasslands and meadows on mountain slopes and in open coniferous forests.[8]
S. spathulatum var. yosemitanum is restricted from southern Oregon to the Sierra Nevada of California. It can be found at 1,200–2,200 m (3,900–7,200 ft) in oak woodlands and coniferous forests.[15]
Conservation
As of July 2021[update], NatureServe listed Symphyotrichum spathulatum as Secure (G5) worldwide and Possibly Extirpated (SX) in Alberta.[1]S. spathulatum var. intermedium and S. spathulatum var. spathulatum were reported as Secure Varieties (T5),[16][17] and no status rank was given for S. spathulatum var. yosemitanum.[18]
Notes
^Occidentales is listed as a section in Flora of Missouri,[10] whereas on Canadian botanist John C. Semple's Astereae Lab website, it is given as a subsection of section Symphyotrichum.[11]
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