The tree mallow (Lavatera arborea) is an attractive plant and no problem here on the shore at Port Seton but it is a tremendous problem just a few miles away to the east on the islands in the Forth.   The islands are important breeding grounds for sea birds especially puffins but the tree mallow has become so invasive that in places it is almost impenetrable, growing 3 metres high and preventing birds from finding places to nest.  Puffins like to nest in burrows but their entrances became blocked causing the numbers of breeding birds to decline but now, after large areas have been cleared by volunteers, the number of pufflings have risen.  On Fidra the number of occupied burrows had gone down to about 400 ten years ago before the plants were removed but now there are over a thousand although further eradication will be necessary each year to help the birds increase in numbers.
The tree mallow was introduced over 300 years ago to Bass Rock where its leaves were used as a poultice by the garrison soldiers and later by lighthouse keepers for wounds and burns and as a type of herbal toilet wipe.  Like many gardeners I have grown a similar plant in a previous garden and enjoyed its spectacular flowers but without any worries of it becoming invasive.

(Port Seton flowers - P challenge)