Symphyotrichum undulatum
Conservation status
Secure  (NatureServe)[1]
Scientific classification
Kingdom:	Plantae
Clade:	Tracheophytes
Clade:	Angiosperms
Clade:	Eudicots
Clade:	Asterids
Order:	Asterales
Family:	Asteraceae
Subtribe:	Symphyotrichinae
Genus:	Symphyotrichum
Subgenus:	Symphyotrichum subg. Symphyotrichum
Section:	Symphyotrichum sect. Symphyotrichum
Species:	S. undulatum
Binomial name
Symphyotrichum undulatum (L.) G.L.Nesom[2]
Native distribution[2]
Synonyms[2]
Basionym Aster undulatus L. Alphabetical list Aster asperifolius E.S.Burgess Aster asperulus Torr. & A.Gray Aster autumnalis Wender. ex Nees Aster baldwinii Torr. & A.Gray Aster claviger E.S.Burgess Aster corrigiatus E.S.Burgess Aster diversifolius Michx. Aster gracilescens E.S.Burgess Aster heteromallus Wender. Aster linguiformis E.S.Burgess Aster loriformis (E.S.Burgess) E.S.Burgess Aster mohrii E.S.Burgess Aster paniculatus Nutt. Aster proteus E.S.Burgess Aster sagittifolius Elliott Aster scaber Elliott Aster sylvestris E.S.Burgess Aster triangularis E.S.Burgess Aster truellius E.S.Burgess Aster undulatus var. abruptifolius E.S.Burgess Aster undulatus var. asperulus Alph.Wood Aster undulatus var. diversifolius (Michx.) A.Gray Aster undulatus var. loriformis E.S.Burgess Aster undulatus var. sylvestris Howe Aster undulatus var. torquatus E.S.Burgess Aster undulatus var. triangularis E.S.Burgess

Symphyotrichum undulatum (formerly Aster undulatus) is a species of flowering plant in the family Asteraceae native to eastern North America. Its common name is wavyleaf aster,^[3] and it is a perennial, herbaceous plant that flowers August through October and may reach heights between 30 and 160 centimeters (1 and 5 feet).

Symphyotrichum undulatum is a perennial, herbaceous plant that flowers from August through October, growing to heights between 30 and 160 centimeters (1 and 5 feet) from a cespitose rootstock. The roots can have short rhizomes or branched and woody caudices.^[3]

There are 12–16, sometimes up to 25, blue to purple or sometimes lilac ray florets of lengths 6–12 millimeters^[a] and widths of 1.4–2.5 mm. These surround 15–22, sometimes up to 25, cream or light yellow disk florets of depths 4–5.8 mm with lanceolate lobes of lengths 0.5–0.9 mm. As the disk florets age, they become purple.^[3]

The fruits (seeds) of Symphyotrichum undulatum are not true achenes but are cypselae, resembling an achene but surrounded by a calyx sheath. This is true for all members of the Asteraceae family.^[4] After pollination, the seeds of S. undulatum become dull purple to light brown or tan with an oblong-obovoid compressed shape, 1.7–2.2 mm in length with 3–4 nerves, and with a few stiff, slender bristles on the surface (strigillose). They also have tufts of hairs (pappi) which are cream or rose-tinged and 3.5–5 mm in length.^[3]

The species has a monoploid number (also called base number) of eight chromosomes (x = 8). Individual plants with 16 and 32 sets of its chromosomes have been found, meaning the species is diploid and tetraploid.^[3]

Symphyotrichum undulatum is native to the Canadian provinces of Nova Scotia and Ontario; and, the U.S. states of Alabama, Connecticut, Delaware, Florida, Georgia, Illinois, Indiana, Kentucky, Louisiana, Maine, Maryland, Massachusetts, Mississippi, New Hampshire, New Jersey, New York, North Carolina, Ohio, Pennsylvania, Rhode Island, South Carolina, Tennessee, Vermont, Virginia, and West Virginia, as well as in the District of Columbia.^[2]

It can be found at elevations between 200 and 1,500 meters (660 and 4,920 feet) in rocky or loamy soils, on sandhills, or on limestone- or sandstone-based bluffs.^[3]

As of October 2022, NatureServe listed S. undulatum as Secure (G5) globally; Secure (S5) in New Jersey, New York, North Carolina, and West Virginia; Apparently Secure (S4) in Virginia; Vulnerable (S3) in Indiana and Nova Scotia; and, Critically Imperiled (S1) in Illinois. The species' global status was last reviewed on 25 July 2016.^[1]