Elder (sambucus nigra)
Elder (not to be confused with alder) can grow to a large shrub or small tree. It has compound (more than one leaflet per leaf), pinnate (the leaflets meet along the stem, not all in one place) leaves. It is often seen as a weed, and doesn't have a pleasant smell, but it is great for wildlife.
In spring, elder has beautiful clusters of small creamy-white flowers. These flowers can be picked and turned into elderflower cordial or even elderflower fritters! *If you are picking any plant to eat, please make absolutely certain that you have identified it correctly first.
In autumn the flowers turn into elderberries, which provide great food for wildlife, particularly birds. Elderberries contain a toxin which can be harmful to humans, so eating them raw is not advised.
Elder's other property is that its stems have a soft, spongy centre which can be hollowed out. In the past these tubes were used in carving and as bellows for the fire. In fact, its name derives from the Anglo Saxon word "aeld" which means fire.
In the past elder was also used to dye fabric. See this article from the Harris Tweed Authority which mentions elder Natural Dyes - The Harris Tweed Authority