Læs på dansk om Buddlejas historie HER

The common names for Buddleia are butterfly bush and summer lilac. Butterfly bush should not be confused with the common herbaceous perennial butterfly weed, Asclepias tuberosa (a plant smoked by delinquent Lepidoptera). The first species of Buddleia known to science was tropical, the Central American Buddleia americana which made its way to Europe from the Caribbean Islands in the 1730s. The Buddleia that we commonly grow today, Buddleia davidii, was not discovered and brought into gardens until the 1890s.

The hundred or so wild Buddleia species have a worldwide distribution between 40°N to 40°S latitude. Buddleia are divided into two groups, the new world Buddleia, which are native from the southeastern United States to Chile, and the old world Buddleia which are native to Africa and Asia.

The commonly grown Buddleia davidii is native from central China to Tibet at elevations up to 7800′ (2600m) and is one of the most cold hardy Buddleia species. There is a large species diversity of Buddleia in Asia and the Americas, but the highest is in South Africa which leads scientists to speculate that they originally evolved there. Some species have a very wide natural range (Buddleia americana, Buddleia asiatica, Buddleia crispa) while others are rare and exist only in a small region (Buddleia coriacea, Buddleia utahensis). Most Buddleia are woody shrubs from 6′ to 16′ in height. Others are 40-80′ tall trees (e.g., Buddleia cordata Buddleia limitanea, Buddleia saligna), some are dwarf shrubs less than 3′ tall (e.g., Buddleia pterocaulis, Buddleia utahensis), some are woody vines (e.g., Buddleia madagascariensis ), and at the northern edge of their geographic range some are herbaceous perennials. Buddleia davidii is a widely grown ornamental plant in temperate areas around the world. Dozens of cultivars have been released covering a wide range of flower color, leaf color, and plant size. It is a very successful ornamental crop for landscape use, container gardening, and cut flowers. In the United States, Buddleia are grown mainly in USDA hardiness zones 5-10, and are herbaceous perennials in the Zone 5 end of the range.

Outside of the garden, Buddleia have only a few economic uses. Some cultures extract dyes or essential oils from the stems or the flowers. Others use extractions from the leaves to treat headaches, burns, wounds, or ulcers. Some species produce important secondary metabolites such as flavinoids, terpenoids, iridoids, or phenylethanoids that may have economic value. The Chinese mix Buddleia lindleyana leaves with coal and throw them into waterways to intoxicate fish who then float to the surface and are easier to harvest. It must be something in the Buddleia leaves since most rivers in China are already full of coal and petroleum products.

The native Chinese species, Buddleia davidii, has a reputation for being weedy in some places. Buddleia are pioneer successionary species: each plant produces millions of seeds and a plant can grow from seed to a mature flowering adult in a single year. The seeds have tiny wings on them and can float a long distance on the wind. Buddleia davidii plants will colonize any piece of bare soil in sunny locations such as roadsides, riparian areas, pastures, and other disturbed areas. After World War II, many of England’s bombed-out home sites had Buddleia growing on them. Even today, the English countryside is painted with Buddleia flowers every summer. Buddleia do not like direct competition from trees or other tall plants, and therefore will die out in area with a climax forest successionary regime.

Buddleia davidii is considered to be an invasive weed in New Zealand, England, France, and the US (Oregon and Washington state). Australia, Fiji, and Hawaii consider it to be potentially invasive and maintain a careful watch. Buddleia davidii has naturalized in England, as well as many US states such as California, Pennsylvania, North Carolina, Virginia, Delaware, Maryland, New Jersey, Kentucky, and West Virginia but is not considered invasive or harmful.

For gardeners whose property borders a non-forested natural area, use the sterile or low fertility cultivars or remove the seed heads in the fall before they open. Many of the modern cultivars of Buddleia davidii have dramatically reduced fertility and are not invasive. Some hybrid cultivars (such as Buddleia ‘Blue Chip’) are almost completely sterile and pose no threat. Some low viability selections include Buddleia weyeriana, Buddleia fallowiana, Buddleia hemsleyana, Buddleia longifolia, Buddleia macrostachya, and Buddleia nivea.

Af Denis Carey og Tony Avent