Conoclinium greggii, also known as Gregg’s blue mistflower and Texas ageratum, is a ground cover native to Texas, New Mexico, Arizona, and northern Mexico. It typically grows to 12-18 inches and spreads up to 24 inches wide. The plant produces powder blue flowers similar to ageratum, blooming from summer to fall. These misty flowers are the reason for the common name of the plant. The plant has light green leaves and is attractive to butterflies. It is synonymous with and sometimes referred to as Eupatorium greggii.

Conoclinium greggii requires medium moisture and well-drained loam in full sun to part shade and grow. It grows best in full sun in St. Louis. In ideal conditions, the plant can spread quite aggressively through rhizomes. Conoclinium greggii is winter-hardy to 
USDA Zone 7.