Horseweed Erigeron speciosus

Translating to 'pretty', 'showy' or 'beautiful', the species name says it all.  Aspen Fleabane is a clump forming perennial wildflower in the daisy family with showy blue-purple flowers that can have 100+ petals surrounding a yellow disk center. 

In the US, it can be found flourishing in South Dakota and each of the states located to the west, with the exception of California.  Wet, dry and rocky grasslands, meadows and open woodlands are its favored locations.  

Performing at its best in fertile, well-drained soil, it will tolerate occasional dry soils.  It does its best when the soil moisture is consistent, not going to extremely wet or dry.  Sun exposure can also have an effect on the plant size.  Where some shade is provided, plants tend to grow taller than if located in full sun.  Areas subjected to frost may see smaller plants as well as later blooming.  

Colonizing will occur as this long-lived plant spreads. Self seeding allows this plant to spread as well as by its rhizomes.  The ecology can also affect its spread.  While grazing by cattle, sheep and wildlife such as deer, mountain goats, gophers and other wildlife will reduce its numbers, wildfires can ultimately increase the number of plants.

Collection of seed is a method of reproduction.  The seed, which do not need any pretreatment, can be spread into new locations to create grazing lands for both domestic and wildlife as well as land restoration.  After spreading, the seed should be covered with a layer of soil.  

Each stem can produce from 1 to 20 flower heads.  Each flower head is up to 2" wide and can have 75 to 150 rays, most often purple, blue or pink.  The centers are yellow or orange center.   Deadheading will encourage additional blooms.  

Insects, Diseases, and Other Plant Problems:  No serious insect or diseases issues.  Occasionally powdery mildew can occur.  

Ensure that leaves from surrounding trees are removed from the vicinity around this plant to prevent rotting.

More information on Erigeron.