Ionactis linariifolia also known as the flax-leaf ankle-aster, flaxleaf whitetop or simply aster<ref>http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=250067004 Flora of North America</ref> is a North American species of plants in the daisy family.
Ionactis linariifolia grows across much of eastern and central North America from Florida north as far as Québec and New Brunswick, and west to extreme eastern Texas.<ref>Biota of North America Program 2014 county distribution map</ref>
Ionactis linariifolia is an herb up to 70 cm (28 inches) tall. Leaves are green, long and narrow, up to 4 cm (1.6 inches) long. The plant usually produces several flower heads in a flat-topped array. Each head has blue, white, or violet ray flowers surrounding numerous yellow disc flowers.<ref>Flora of North America, Ionactis linariifolia (Linnaeus) Greene, 1897. Flax-leaf ankle-aster, flaxleaf whitetop or aster, aster à feuilles de linaires </ref>
It was initially classified by Carolus Linnaeus as Aster linariifolius,<ref>Linnaeus, Carl von. 1753. Species Plantarum 2: 874 in Latin</ref> known as the stiff-leafed aster.<ref>Annotated Checklist of the Vascular Plants of the Washington - Baltimore area, page 22</ref>Ionactis was classified as a separate genus by Edward Lee Greene in 1897.<ref>Greene, Edward Lee. 1897. Pittonia 3(17C): 245–246</ref>