Doellingeria umbellata

 Flat-top White Aster

• Full sun or part shade
• Highly adaptable. Will tolerate quite poor soil, especially in sunny locations. Will also grow well in average moisture or even seasonally wet areas.
• Height varies between 36" in sunny, dry settings to 60" in rich settings with plenty of moisture. Not quick to spread, I'd recommend a spacing of 12" to 24".
• Garden settings, dry to wet meadows, open woodlands. 

Despite their very wide distribution, I didn’t get to know this Aster until the last few years. I’m not sure how I missed them. Blooming enthusiastically in September, they are easily visible along roadsides, even at highway driving speeds. I’ve seen them in shallow, shale soil that bakes in the sun all day, growing only 20” or so inches tall but still holding aloft a lovely spray of blooms. They almost look like a very show, very late blooming yarrow from a distance. I’ve also seen them growing in seasonally wet ditches where they are shaded through half of the day. The plants there are much taller, between 4’ and 5’ with huge clusters of blooms, as much as 12” across.
Adaptability is definitely their style.
I would pair these with Verbena hastata, blue and red Lobelias, Swamp Rose Mallow, Swamp Milkweed, Joe-Pye weed and, if you have plenty of space, Cup Plant in a damp area.
In a dry meadow I’d pair them with Orange Butterfly weed, Common Milkweed, Coreopsis, Early Goldenrod, Common Sneezeweed and, if it wasn’t terribly dry, Virginia Mountain-Mint, Wild Beebalm and Hairy Beardtongue.