Danainae butterflies like to visit these plants. One reason is to drink the sap which renders the butterflies noxious to predators. Some species collect olfactory compounds to produce a kind of "perfume" to attract mates. Caterpillars of the Grass Jewel (Freyeria trochylus), a gossamer-winged butterfly, feed on H. strigosum.
Several heliotropes are popular garden plants, most notably Garden Heliotrope (H. arborescens). Some species are weeds and many are hepatotoxic if eaten in large quantities due to abundant pyrrolizidine alkaloids. The sap of heliotrope flowers, namely of European Heliotrope (H. europaeum), was used as a food coloring in Middle Ages and Early Modern French cuisine.