Buddleja fallowiana var. alba
Species: Buddleja fallowiana
Trinomial name: Buddleja fallowiana var. alba
Synonyms: Buddleja fallowiana, Buddleja fallowiana 'Sabourin'
Buddleja fallowiana var. alba is a white-flowered variety of B. fallowiana endemic to Yunnan in western China, where it grows in open woodland, along forest edges and watercourses.
B. fallowiana var. alba is a deciduous, comparatively slow-growing shrub of loose habit, typically growing to a height and width of < 1.7 × 2 m. The young shoots are clothed with a dense white felt. The leaves are lanceolate, tapering to a fine point, with shallowly toothed margins. The size of the leaves varies considerably according to the vigour of the shoot, and can reach 25 cm long by 8 cm wide, the upper surfaces glabrescent and dark-green, the lower surfaces densely tomentose. The inflorescences are lax narrow panicles < 25 cm long by 2.5 – 3 cm wide, and comprise vanilla-scented white flowers with yellow eyes, the corollas 10 mm long. The flowers bloom in during summer and autumn.
Buddleia species can be 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 wind blown.
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 some insects such as butterflies eat nectar provided by the buddjeia flowers, its potenial impact on native ecosystems far outweighs ts food value.