Thursday, April 18, 2013
Propping up the banks........
Butterbur flower spikes are rapidly elongating all along the banks of local rivers here in County Durham. There is actually more butterbur biomass below ground than above at this time of year, although that situation reverses once the massive, rhubarb-like leaves develop fully in a few weeks' time.
The plant grows from a thick, branching underground rhizome that stores starch through the winter, enabling it to flower at the earliest opportunity, before the leaves expand and start photosynthesising. Sometimes winter floods expose some of the rhizomes with their mass of fibrous roots, that can play a valuable role in stabilising riverbanks.
Where there's no network of butterbur roots winter floods can rapidly erode riverbanks, as they have done here along the river Browney near Croxdale in Durham. A woven willow bank reinforcement has been installed by the Woodland Trust to limit the damage and trap silt.
A little further upstream along the Browney this remarkable display of what must easiliy be more than a 1000 butterbur inflorescences testifies to a dense mass of rhizomes below ground, that are doing a good job of stabilising the river bank.