The distinctive feature of this annual wildflower is the scent of its leaves which smell just like pineapple. It forms extensive patches on disturbed ground, tracks, pathways and other well-trodden places. It is quite unusual in that it is without ray florets, having only small greenish-yellow conical heads of disc florets (8-12mm across). They flower from May through to November. These heads are closely back by overlapping flower-bracts. If the flowers are plain, the leaves make up for it. They are feathery, pinnately divided and well branched and it is when they are crushed that the pineapple smell happens. This is not a native plant, in fact it was first found in Ireland near Dublin in 1894. It belongs to the family Asteraceae.
My first sighting of this plant was in Bray, Co Wicklow in 1977. I photographed it in Ballitore, Co Kildare in 2005.
If you are satisfied you have correctly identified this plant, please submit your sighting to the National Biodiversity Data Centre