Description: Tall spikes of purple flowers that bloom in late summer.
Growth Habit: Upright, clump-forming perennial. 5ft height
Sun/Shade: Full sun.
Water Needs: Low to moderate; drought-tolerant.
Soil Preferences: Well-drained, sandy or loamy soil.
Benefits: Attracts monarch butterflies and other pollinators. Great for prairie plantings.
 
From Prairie Moon Nursery:
 
The ultimate Monarch butterfly magnet!  Seriously - plant it and they will come. The beautiful purple blossoms of this Liatris should be your first choice for attracting Monarch and other butterflies to sunny, medium-soil sites in late summer.  It's not uncommon to see dozens of Monarchs nectaring on a stand of Meadow Blazing Star. It blooms primarily in August, just when the Monarchs are preparing for their long migration south; a synchronization that has evolved over hundreds of years, and a good example of how native plants and pollinators are deeply dependent on one another.

These upright plants can reach 5' in rich soils; in a garden setting you may want to stake them.  The height of this Liatris make it an easy target for Monarchs and other butterflies and birds to feed.  Blossoms often appear all at once along stems and last for many weeks late summer.  Birds find the seeds appealing later in the year.