is much milder. Goldenrods are, in some places, considered a sign of good luck or good fortune. They are considered weeds by many in North America, but they are prized as garden plants in Europe, where British gardeners adopted goldenrod as a garden subject. Goldenrod began to gain some acceptance in U.S. gardening (other than wildflower gardening) during the 1980s. They have become invasive species in many other parts of the world, including China, Japan, Europe and Africa. Solidago canadensis, which was introduced as a garden plant in Central Europe, has become common in the wild, and in Germany is considered an invasive species that displaces native vegetation from its natural habitat. Goldenrod species are used as a food source by the larvae of many Lepidoptera species. The invading larva may induce the plant to form a bulbous tissue mass called a gall around it, upon which the larva then feeds. Various parasitoid wasps find these galls and lay eggs in the larvae, penetrating the bulb with their ovipositors. Woodpeckers are known to peck open the galls and eat the insects in the center. Cultivated species Cultivated goldenrods include S. bicolor, S. caesia, S. canadensis, S. cutleri, S. riddellii, S. rigida, S. shortii, and S. virgaurea. A number of cultivars have been selected, including several of hybrid origin. A putative hybrid with aster, known as ×Solidaster is less unruly, with pale yellow flowers, equally suitable for dried arrangements. Molecular and other evidence points to ×Solidaster (at least the cultivar 'Lemore') being a hybrid of Solidago ptarmicoides and Solidago canadensis, the former now in Solidago, but likely the "aster" in question. The cultivars 'Goldenmosa' and S. × luteus 'Lemore' have gained the Royal Horticultural Society's Award of Garden Merit. Industrial use Inventor Thomas Edison experimented with goldenrod to produce rubber, which it contains naturally. Edison created a fertilization and cultivation process to maximize the rubber content in each plant. His experiments produced a plant that yielded as much as 12% rubber. The tires on the Model T given to him by his friend Henry Ford were made from goldenrod. Like George Washington Carver, Henry Ford was deeply interested in the regenerative properties of soil and the potential of alternative crops such as peanuts and soybeans to produce plastics, paint, fuel and other products. Ford had long believed that the world would eventually need a substitute for gasoline, and supported the production