Buddleja (also spelled Buddleia) is a genus of more than 140 species of flowering shrubs and occasionally small trees in the family Scrophulariaceae, order Lamiales. Native to Asia, Africa, and the Americas, buddlejas are absent as wild plants from Europe and Australasia, yet are among the most familiar garden shrubs in temperate gardens worldwide.
Most species are shrubs under 5 m tall, though a handful reach tree stature, the largest growing to 30 m. Both evergreen and deciduous forms exist, with deciduous species typically occupying temperate regions and evergreen ones the tropics. Leaves are usually lanceolate and arranged in opposite pairs along the stems, ranging from 1 to 30 cm long. Flowers are small and tubular, divided into four spreading lobes, and borne in dense terminal panicles (Asiatic species) or rounded cymose heads (American species). They are generally rich in nectar and frequently honey-scented. Flower colour spans a wide range: pastel pinks, lilacs, and blues predominate among Asiatic species, while the New World species include vivid yellows and reds — some South American taxa have evolved long red tubes to attract hummingbirds as exclusive pollinators. The fruit is a small dry capsule holding numerous tiny seeds; a few species bear fleshy berry-like capsules.
The genus is named in honour of Adam Buddle (1662–1715), an English botanist and rector, by Linnaeus, on the suggestion of William Houstoun, who introduced the first scientifically documented buddleja (B. americana) to England from the Caribbean.
Buddleja davidii, native to central China and named for the French missionary-naturalist Père Armand David, is by far the most widely grown species. Known as the butterfly bush, it is prized for its long, fragrant, nectar-rich flower spikes that attract butterflies, bees, and moths in large numbers. It has, however, become an invasive weed in parts of Europe and North America, readily self-seeding on waste ground, railway embankments, and old masonry — earning the nickname "the bomb-site plant" in post-war Britain. Several US states have banned fertile cultivars, prompting breeders to develop seed-sterile selections.
Other cultivated species include B. globosa (introduced to Britain from southern Chile in 1774), grown for its strongly scented orange globular flower-heads, and the graceful weeping B. alternifolia. Numerous interspecific hybrids are in cultivation, including B. 'Lochinch' and B. × weyeriana.
Etymology
The genus name Buddleja was bestowed by Linnaeus to honour Adam Buddle (1662–1715), an English botanist and rector. The name was applied posthumously, at the suggestion of William Houstoun, who had sent the first plants of the genus (B. americana) to England from the Caribbean around 15 years after Buddle's death. The spelling Buddleia is a widely used orthographic variant, particularly in horticulture.
Distribution
Buddleja occurs naturally across four continents: more than 60 species are native to the Americas, ranging from the southern United States south to Chile, while further species are distributed across Africa and Asia. The genus is entirely absent as a native plant from Europe and Australasia. New World species are mostly dioecious, while Old World species are hermaphrodite with perfect flowers.
Ecology
Buddleja flowers are nectar-rich and strongly scented, making them highly attractive to butterflies, bees, and moths — hence the common name "butterfly bush". Some South American species have evolved long red tubular flowers to attract hummingbirds as pollinators. Buddleja davidii is a vigorous coloniser of disturbed, dry, open ground, including railway embankments, old masonry, and post-industrial waste land, and is classified as an invasive species in parts of Europe and North America.
Cultivation
Buddlejas became popular garden shrubs primarily in the 20th century, with the exception of B. globosa, introduced to Britain from southern Chile in 1774. Buddleja davidii is the most widely grown species, available in numerous cultivars including 'Royal Red', 'Black Knight', 'Sungold', and 'Pink Delight'. Because of the invasiveness of fertile seed, breeders have developed seed-sterile cultivars as a preferred choice in regions where planting fertile forms is restricted or banned.
Taxonomy Notes
The genus was published by Linnaeus in 1753 (Sp. Pl.: 112) under the spelling Buddleja; the variant Buddleia is an orthographic variant used in horticulture. Taxonomic placement has shifted over time: the genus has been placed in Loganiaceae, the now-defunct family Buddlejaceae, and is currently accepted in Scrophulariaceae (order Lamiales) by the major checklists. Significant species-level contention also exists; the late Toon Leeuwenberg sank many formerly distinct Asiatic species into Buddleja crispa, an arrangement adopted in the Flora of China.
