Species of the Month - March 2017

Butterbur

Petasites hybridus

Butterbur forms large patches in damp places at low altitude.  The flower spikes emerge between February and early April, and the leaves begin to emerge about the same time but don't reach full size until after the flowers have finished.  The leaves eventually become as big as rhubarb leaves and cover the ground over a large area, forming unbroken shade which prevents other plants from growing between them.  The leaves arise singly, not in tufts from a crown like those of rhubarb.
 

Butterbur provides a feast for bumblebees at a time when few other plants are in flower.  On a sunny day a patch of Butterbur is a good place to watch the behaviour of bees and other early spring insects.
 

Each flowering spike has many closely-packed inflorescences, which themselves consist of 20 or more tubular male flowers in the centre and a few rayed female flowers around the edge.  In some parts of Britain there is another form of Butterbur with about 100 female flowers in the inflorescence and only a few male ones, but that form does not occur in our area.
 

When Butterbur colonises a damp patch of ground next to a burn, it will often put up shoots in the flowing water of the burn itself, but they struggle to survive there.

A patch of leaves which have almost reached their full size after the flowers have died down.

Each inflorescence is surrounded by a pinkish-gold involucre, and has a narrow pink bract at its base.
 

BEWARE WINTER HELIOTROPE!

This is Winter Heliotrope, an introduced species similar to Butterbur but with much shorter flowering spikes consisting of only about 10 inflorescences, not closely packed together.  It can flower as early as December but continues through March.  Its leaves form large patches like those of Butterbur, but each leaf is only to about 20 cm wide, whereas those of Butterbur can be up to 100 cm.  It tends to be in drier and less flat places than Butterbur, often on roadside banks.

Please send in your Butterbur sightings using the form below, or email sightings@lnhg.org.uk with the details if you prefer.  If you are not sure of the identity of your plant, please send a photo to sightings@lnhg.org.uk, or put one on the LNHG Facebook page.