These three thistles bloom from high summer until autumn. They are excellent for attracting a wide variety of insects because of their plentiful supplies of nectar. Their seeds are eaten by birds, especially goldfinches. They are also the foodplants of the Painted lady butterfly. (1)
Spear thistle (Cirsium vulgare) or Feochadán colgach in Irish is common now on roadside verges, pastures and waste ground. (2a) The deep purple flowerhead is clasped by a large, spiny involucre of bracts. The bracts which protect the flower head are modified leaves. Its leaves and stem have sharp spines to deter grazers. Each leaf ends in a spear-like spike. (2b) This thistle which is believed to be the emblem of Scotland grows to about 1.5 metres.
Creeping thistle (Cirsium arvense) or Feochadán reatha in Irish is not as spiny as Spear thistle. (3) Its flowerheads are pale purple. This is the only perennial thistle of the three mentioned here. It spreads rapidly by seeds and a creeping underground stem called a rhizome and as a result it can colonise gardens and arable fields quickly. Because of its copious amounts of nectar, it attracts many insects including butterflies, bees, beetles and wasps.
Marsh thistle (Cirsium palustre) or Feochadán corraigh in Irish has small flowerheads that are coloured a deeper purple than the two above. (4a) It is a stately plant with stems that are relatively bare. (4b) The few leaves it has are narrow and spiny. As its name suggests it likes damp places, but it will also grow on dry roadside verges and dry pastures. Like other thistles its seeds are attached to tiny white parachutes which spread them far and wide.