Buddleja (butterfly bush)

Buddleja davidii

Of the approximately 100 species nearly all are shrubs <5 m (16 ft) tall, but a few qualify as trees, the largest reaching 30 m (98 ft). Both evergreen and deciduous species occur, in tropical and temperate regions resp. The leaves are lanceolate in most species, and arranged in opposite pairs on the stems (alternate in one species, B. alternifolia); they range from 1–30 cm (0.39–11.81 in) long. The flowers of the Asiatic species are mostly produced in terminal panicles 10–50 cm (3.9–19.7 in) long; the American species more commonly as cymes forming small, globose heads. Each individual flower is tubular and divided into four spreading lobes (petals) about 3–4 mm (0.12–0.16 in) across, thecorolla length ranging from around 10 mm in the Asiatics to 3–30 mm in the American species, the wider variation in the latter because some South American species have evolved long red flowers to attract hummingbirds, rather than insects, as exclusive pollinators.

The colour of the flowers varies widely, from mostly pastel pinks and blues in Asia, to vibrant yellows and reds in the New World, while many cultivars have deeper tones. The flowers are generally rich in nectar and often strongly honey-scented. The fruit is a small capsule about 1 cm (0.39 in) long and 1–2 mm (0.039–0.079 in) diameter, containing numerous small seeds; in a few species (previously classified in the separate genus Nicodemia) the capsule is soft and fleshy, forming a berry.