Elderberry is a deciduous shrub or small tree growing to tall and wide, rarely reaching tall. The bark, light grey when young, changes to a coarse grey outer bark with lengthwise furrowing, lenticels prominent. The leaves are arranged in opposite pairs, 10–30 cm long, pinnate with five to seven (rarely nine) leaflets, the leaflets 5–12 cm long and 3–5 cm broad, with a serrated margin. The young stems are hollow. The English term for the tree is not believed to come from the word "old", but from the Anglo Saxon "æld", meaning fire, because the hollow stems of the branches were used as bellows to blow air into a fire.