T.E.R:R.A.I.N - Taranaki Educational Resource: Research, Analysis and Information Network

Buddleja davidii (Butterfly Bush)

Kingdom: Plantae
(unranked): Angiosperms
(unranked): Eudicots
(unranked): Asterids 
Order: Lamiales
Family: Buddlejaceae 
Genus: Buddleja 
Species: B. davidii 
Binomial name: Buddleja davidii (Orange-eye)
Common name: Buddleia, Summer lilac, Butterfly-bush, Orange eye

Buddleja davidii is native to Sichuan and Hubei provinces in central China, and also Japan.
It is a vigorous shrub with an arching habit, growing to 5 m in height. The pale brown bark becomes deeply fissured with age. The branches are quadrangular in section, the younger shoots covered in a dense indumentum. The opposite lanceolate leaves are 7–13 cm long, tomentose beneath when young.
 In early summer, the plant produces numerous tapering heads of sweetly scented lilac flowers with orange centres. The honey-scented white - pink - lilac - purple inflorescences are terminal panicles, < 20 cm long. Flowers are perfect (that is having both male and female parts), hence are hermaphrodite rather than monoecious (separate male and female flowers on the same plant).

Buddleia is a major weed and is very invasive and is common throughout New Zealand and forms dense stands in a wide range of habitats. In riverbeds, it can alter water flow, causing silt to build up and flooding problems. Buddleia is extremely ecologically versatile, tolerating a wide range of soils, especially poor soils. It can tolerate frost and a wide range of conditions. Thickets establish and grow quickly, and are self-replacing. It invades river beds, stream sides, disturbed forest, shrubland margins and bare land. It reseeds profusely into bared sites and cut stumps will also resprout. Spread by fine seed which is windblown.

A Chinese weevil Cleopus japonicus was introduced in 2006 as a weed biocontrol agent and its impact) continues to impress with some buddleia bushes being completely defoliated.
The weevil lays its eggs on the leaves of buddleia bushes. The eggs hatch and grow into a yellowish grub up to 5mm in length (like a small maggot), which eats away at the leaves, defoliating the plant, much like monarch caterpillars on swan plants. However, in this case, the grub stunts the buddleia’s growth and can even eventually kill it. The grub pupates in a cocoon on the leaf, eventually emerging as the adult weevil that can fly to a new plant to mate. Although some insects such as butterflies eat nectar provided by the buddleia flowers,  its potential impact on native ecosystems far outweighs its food value

Photos below are of different varieties of Buddleja davidii

Young buds

Buddleja davidii top surface of a leaf

Buddleja davidii underside of a leaf

Thanks to Wikipedia for text and information: https://creativecommons.org/licenses/by-sa/3.0/