Heliotropium amplexicaule aka Blue Heliotrope

Heliotropium amplexicaule spreads and lives for more than one year. It belongs to the borage family, Boraginaceae. Its names include blue heliotrope, clasping heliotrope, and summer heliotrope. It is native from Bolivia to Brazil and northern Argentina. Kew calls it a subshrub from subtropical regions. It has spread to parts of the United States. These lie beyond its native range. They include the Gulf Coast, Southeast, and Mid-Atlantic states.

Plants grow about 1–2 feet [0.30–0.61 metres] tall. One detailed size list gives 0.67–1.67 feet [0.20–0.51 metres]. Plants spread 2–3 feet [0.61–0.91 metres] wide. Low stems spread across the ground. Rhizomes, or stems below ground, help groups of plants spread. Fast growth can crowd out native plants. Green leaves grow in turn along the stems. Each simple leaf has a lance shape. It clasps the stem and has no stalk. Leaves have a scent, sunken veins, and sticky hairs. Their soft blades have round teeth at the edges. Stems have hairs but no scent.

Small flowers grow in groups called cymes in summer and fall. Blooms range from blue to purple and have yellow throats. Each has four or five petals. Their shape is like a bell or tube. Flowers line one side of thin, forked stalks. These stalks curl back. The long bloom season draws pollinators to the plant. Brown fruit forms after the flowers. Each fruit is a schizocarp. It splits into two rough, dry nutlets.

The plant suits full sun but accepts part shade. It prefers acidic sandy loam that drains well. It grows in neutral soil too. Listed soils include loam, sand, and shallow rocky ground. Once plants take root, they cope with drought and dry soil. North Carolina State lists USDA zones 7a–9b for growing it. Gardeners use it to cover ground and in pots. They also use it in rock gardens and drought-tolerant planting. You can grow new plants by division or stem cuttings.

Its invasive spread limits its worth as a garden plant. It can escape gardens, spread through pastures, and poison livestock. Australia lists it as a noxious weed. Keep it away from children and pets. All listed plant parts contain poisonous pyrrolizidine alkaloids. Eating them can upset the gut and harm the liver. Reported pests include aphids and mealybugs. Spider mites and lace bugs also appear on pest lists. Slugs and snails may cause harm too. Listed diseases include powdery mildew and root rot.