Sp. Pl. 1: 112. 1753.
Shrubs or trees; stolons absent. Stems erect or pendent, hairy when young, hairs usually stellate and glandular. Leaves persistent, semipersistent, or deciduous, cauline, opposite, decussate; stipules present (B. davidii) or as stipular lines or absent; petiole present or absent; blade not fleshy, subleathery or not, margins crenate, dentate, undulate, serrate, sinuate-dentate, subentire, or entire, sometimes involute. Inflorescences terminal, rarely axillary, cymes in heads, pseudoverticellate spikes, or panicles; bracts present. Pedicels often absent; bracteoles present or absent. Flowers bisexual, sometimes functionally dioecious, rarely trioecious; sepals 4, calyx radially symmetric, campanulate, lobes ovate to lanceolate; petals 4, corolla yellow, yellowish orange, greenish yellow, purple, pink, or white, sometimes with yellow-orange eye or white throat, radially symmetric, campanulate-rotate, salverform, funnelform, or tubular; stamens 4, adnate to corolla tube, included, rarely exserted, equal, filaments glabrous, staminode 0; ovary 2- or 4-locular, placentation axile; stigma capitate, clavate, or clavate and slightly 2-lobed. Fruits berries or capsules, ovoid or globular to cylindric, oblong, ellipsoid, or subglobular, dehiscence septicidal and/or loculicidal, rarely indehiscent. Seeds 20–100+, yellow to brown, tetrahedral, fusiform, or threadlike (B. davidii), usually obcompressed, wings present or absent. x = 19.
North America, Mexico, Central America, South America, Asia, e Africa, Indian Ocean Islands (Comoro, Madagascar, Mascarene Islands), introduced in Europe, elsewhere in Africa, Pacific Islands (Hawaii, New Zealand), Australia.
Species ca. 100 (10 in the flora).
Buddleja species, especially Asiatic ones, are cultivated widely for their attractive flowers and leaves and their pleasant floral scent. Some plants readily persist and spread after cultivation; one of these, B. davidii, is considered an invasive of concern in some parts of the world (N. G. Tallent-Halsell and M. S. Watt 2009). Some species are used as remedies in folk medicine (E. M. Norman 2000). Almost all buddlejas thrive in sunny disturbed habitats.
The Buddleja species of Madagascar and nearby islands have berries rather than capsules and have been segregated by some authors into Nicodemia; African taxa that have flowers with open corollas with well-exserted stamens rather than tubular flowers with included, sessile or subsessile stamens have been referred to Chilianthus. Here both are treated in Buddleja.
J. F. Chau et al. (2017) conducted a phylogenetic study of Buddlejeae with the five genera of the tribe all treated within seven sections of Buddleja. This treatment is consistent with that study except for recognition of Emorya.
|1||Inflorescences broadly paniculate; corollas white; stamens exserted from corolla tube.||Buddleja saligna|
|1||Inflorescences narrowly paniculate, spicate, racemose, or capitate; corollas yellow, yellowish orange, greenish yellow, orange, purple, violet, or pink, rarely white, sometimes with yellow-orange eye or white throat; stamens included in corolla tube.||> 2|
|2||Corollas tubular or salverform, tubes 7–14 mm.||> 3|
|3||Leaf blades orbiculate to elliptic; corollas greenish yellow.||Buddleja indica|
|3||Leaf blades ovate, ovate-lanceolate, or elliptic; corollas yellowish orange, purple, violet, pink, or white, sometimes with yellow-orange eye or white throat.||> 4|
|4||Corollas yellowish orange; stamens inserted near throat.||Buddleja madagascariensis|
|4||Corollas purple, violet, pink, or white, sometimes with yellow-orange eye or white throat; stamens inserted medially or 3–5 from base.||> 5|
|5||Cymes almost encircling inflorescence axis; corollas straight.||Buddleja davidii|
|5||Cymes secund; corollas curved.||Buddleja lindleyana|
|2||Corollas funnelform, salverform, or campanulate-rotate, tubes 1.5–5 mm.||> 6|
|6||Leaf blade adaxial surfaces glabrous or glabrescent.||> 7|
|7||Shrubs, 3–15 dm; cymes 6–12-flowered; corolla lobes orbiculate.||Buddleja racemosa|
|7||Shrubs or trees, 15–40 dm; cymes 10–35-flowered; corolla lobes ovate.||Buddleja sessiliflora|
|6||Leaf blade surfaces glandular-tomentose (grayish).||> 8|
|8||Inflorescences capitate; corollas deep yellow (turning orange).||Buddleja marrubiifolia|
|8||Inflorescences pseudoverticillate spikes; corollas light yellow, lemon yellow, or greenish yellow.||> 9|
|9||Corolla tubes 1.5–2 mm, lobes oblong.||Buddleja scordioides|
|9||Corolla tubes 4–5 mm, lobes orbiculate.||Buddleja utahensis|