In any normal year, many of us would now be returning from our summer holidays, perhaps, like me, with a bottle of the local aperitif or digestive? However, come the Yorkshire winter, that glass of chilled Pernod or Ouzo and water never tastes quite the same as it did at that French café or Greek Taverna! Likewise, our Victorian botanical and horticultural ancestors often returned from trips overseas with plants for their collections and gardens. The only problem is that some of these plants decided to go exploring themselves, jumping over the garden wall and in some cases spreading aggressively into our countryside. These are what we now refer to as “Invasive Aliens”. The most notable three are Himalayan Balsam, Giant Hogweed and Japanese Knotweed.
Himalayan or Indian Balsam (Impatiens glandulifera) is now in flower along our riverbanks, ditches and canals. I have been following its progress on one of my regular running routes. Amazingly, this plant, which often reaches two metres in height, is an annual, growing from seed every year. Early in spring as I jogged by, just the two seed leaves or cotyledons were showing above ground. Now they stand almost as tall as me.
Introduced into British gardens in 1839, it was first recorded in the wild in 1855. The spread has been rapid across most of England and Wales. It forms dense thickets, outcompeting our native species, altering the ecological balance and changing the character of our wetlands. The spread has been aided by the explosive nature of the seed capsule, projecting seeds up to four metres, often into the river and canal systems to spread even further away from the parent plant. It needs to be controlled, and further information can be obtained from www.nonnativespecies.org
The seed capsule also gives the plant its generic name - Impatiens. Latin for impatient or hasty, in allusion to the manner in which the capsule bursts open and scattering its seeds when lightly touched.
If not loved by humankind, it is by bees. Bees walk into the flower, disappearing out of sight, and draw the nectar from the short-curved spur at the base of the flower. Measuring only 5mm in length, it makes the nectar available to all bees, not just the long-tongued bumblebees. This gives the plant the popular name of “bee bums” due to the common sight of the rear end of bumblebees sticking out of the balsam flowers. As a former beekeeper, when the worker bees returned to the hive with white pollen sacs rather than yellow, I knew exactly where they had been foraging; Himalayan Balsam!