Verbena rigida aka Veined Verbena

Verbena rigida is a perennial in the verbena family, Verbenaceae. Its native range runs from Bolivia to Uruguay in South America. Gardeners call it slender vervain, sandpaper verbena, or tuberous vervain. It has tubers and spreads through underground rhizomes. It has also naturalized from southeastern North Carolina to Florida. In colder regions, gardeners grow it as an annual.

Plants form upright mounds that spread across the ground. Most reach about 1–2 feet (0.3–0.6 metres) tall. The RHS gives a higher limit of 3.3 feet (1 metre). Plants spread about 1–1.6 feet (0.3–0.5 metres) wide. They reach full size in one to two years. Green stems can form roots where their nodes touch soil. The simple leaves grow in opposite pairs and drop seasonally. Their shape ranges from oblong to lanceolate. Rough surfaces and coarse teeth give the leaves their sandpaper feel. Leaf descriptions give lengths of about 0.17–0.33 feet (0.05–0.10 metres).

Small tubular flowers form clusters on stiff, upright flower spikes. The stems branch and carry purple to lilac blooms. Each cluster spans about 0.17–0.25 feet (0.05–0.08 metres). The flowers have four or five petals and a scent. Bloom runs from summer into fall, with late-summer flowers noted by the RHS. Butterflies visit the flowers, and the plant also attracts songbirds. The fruit is a capsule.

Give this plant full sun and soil that drains well. The RHS favors moist soil, though established plants tolerate drought. It also copes well with heat and occasional dry soil. Suitable soils include sand, loam, clay, and chalk. It accepts acidic, neutral, and alkaline conditions. Wet soil in winter is a problem. North Carolina State lists USDA zones 7b–10b. It also notes a need for winter protection in zone 7. The RHS rates it H3 for mild or coastal UK sites.

Use it in sunny borders, containers, rock gardens, or mass plantings. Its spreading habit also suits ground cover and garden edges. The long bloom season adds value to butterfly and pollinator gardens. Growth is moderate, and care needs are low. No routine pruning is needed. Propagate it from seed or stem-tip cuttings; root cuttings are another option. Slugs, aphids, and leafhoppers may attack it. Powdery mildew can also occur. Deer resistance is not complete, since deer sometimes damage plants.