Thy typical railside Buddleia tends to be a Buddleja davidii or “Butterfly Bush” variant, originally found in the mountains near the Tibetan-Chinese border in 1869 by the French missionary Père David. After a hesitant start with apparently weak early imports, propagation caught on at the turn of the century .
Looking at front yards, waste grounds and railway lines in England now, it’s hard to believe that Buddleja is not a plant at all native to Europe. Its 100 something species colonize the warmer parts of the Americas, Africa and Asia.
Buddleja, the invasive species
As Margarete points our in her vividly illustrated blog entry, Buddlejas are easy to care for, not fussy as it comes to soil and habitat. They do like it warm and sunny though, but don’t require intensive watering. ACD Arboriculture consultant Mark even suggests Buddleja to be considered as a plant for future climate change landscaping. Whether hotter, drier weather and/or effective propagation, Buddlejas are found on the list of invasive species in the UK and US.
Buddleja, the bee hotspot
On a sunny summer day, Buddlejas are a bee, butterfly and moth hotspot providing nectar and pollen for a variety of pollinators. It’s a humming and buzzing affair! Careful though: Standing next to one means you’re in a busy flight path 😉
Apart from the mainly decorative B. davidii, the Chelsea Physic Garden, contains a shrub of the medicinally used B. officinalis. It’s all in the name: B. officinalis has been used to treat a variety of illnesses from gonorrhoea and hepatitis  to headaches and inflammatory diseases e.g. in traditional Korean medicine. And reasearch continues into its various medicinally active compounds .
 Richard Mabey, FLORA BRITANNICA the concise edition, 1998
 www.pfaf.org, Plants For A Future, 1996-2008
 Lee et al., Biol Pharm Bull. 2006