Buddleja Breeding
B.madagascarensis x B.crispa.
The genus Buddleja consists of over 100 species of woody perennials and shrubs. Buddleja davidii is the most common and widely cultivated species in this genus. It is a herbaceous perennial in colder USDA zones 5 and 6, but a woody shrub in the warmer climates of Zone 7 and farther south. It is a popular plant in gardens today because it attracts a wide range of butterflies, bees, and moths to the garden. However, butterfly bush is not the perfect garden shrub. One particular problem that is noted with B. davidii is its tendency towards invasiveness in certain areas where it is cultivated.
Despite the extensive use and high popularity of B. davidii, few other species in this genus are cultivated to any great extent even though they offer many desirable characteristics not found in B. davidii. Most of these underused species are subtropical and tropical plants, which lack enough winter hardiness to be utilized as B. davidii in a temperate landscape. The goals of this breeding program are to incorporate the ornamental features found in this underused species into B. davidii cultivars. These characters include leaf shape (such as the oak-shaped leaf of the African species B. indica) and new flower colors (such as the orange flower color of the South American species B. stachyoides and B. tubiflora). Attempts are also underway to produce sterile butterfly bush hybrids through interspecific hybridization.