Calyptocarpus vialis aka Creeping Cinderella Weed

Calyptocarpus vialis is a low perennial in the daisy family. Common names include horseherb, carpet daisy, and straggler daisy. Its native range runs from the southeastern United States to Belize. It also spans the Caribbean and reaches Venezuela. Native US states include Texas, Louisiana, Mississippi, Alabama, and Florida. People have introduced it into other states. It grows in woods, meadows, roadsides, and disturbed ground.

Horseherb forms a creeping ground cover with a low, spreading shape. Plants reach 0.5–1 foot [0.15–0.3 metres] tall and wide. Underground stolons help them spread when conditions suit them. Growth is fast, and the foliage is semi-evergreen. The simple green leaves grow in opposite pairs. They range from triangular to lance-shaped, with toothed edges. Each leaf measures about 0.04–0.08 feet [0.013–0.025 metres] long. Green stems bear hairs and may show thin red stripes. The stems are round in cross section and lack scent.

Small yellow flower heads appear from spring through fall. Plants may flower all year where frost does not occur. Each head has three to eight yellow ray flowers. These surround a center of 10 to 20 disc flowers. Their nectar draws small butterflies, including sulfurs and skippers. After flowering, plants form brown, dry fruits called achenes. Each fruit holds one seed and bears stiff bristles. These bristles help the seeds move to new places.

Horseherb prefers shade or dappled light but accepts more sun. It grows best in sandy soil that drains well. It also grows in loam and clay across a broad pH range. Soil can stay moist or dry out at times. The plant tolerates drought and suits USDA zones 7–10. Gardeners can grow it from divisions or root cuttings. Seed also works, though collecting much seed can be hard. Its care needs are low, though spread may need control.

Use horseherb as a grass substitute in dry, shaded sites. It also covers slopes and suits mass planting. Plants tolerate mowing and foot traffic, and resist deer and rabbits. Yet their spread can make them weeds in lawns and beds. Wet soil can cause root rot. Heavy leaf litter from trees above can hamper growth. NC State lists the leaves as edible for people and animals. It also reports research into medicinal uses, without giving a proven treatment.