Scientific name: Senecio aquaticus Hill
Common name: Marsh ragweed
Description
Habit: Perennial, 30-140 cm high.
Stems: Stout, hairless or slightly woolly.
Leaves: Deeply pinnatifid, the lower ones with the terminal lobe much larger than other lobes; segments toothed; lower leaves usually persisting until flowering time.
Flowers: Yellow, flower-heads 25-30 mm across, in a loose corymb; involucral bracts narrow-elliptical, outer ones few and small; inner ones usually dark-tipped; outer florets ligulate, radiating, numerous, rarely absent; inner florets tubular.
Fruits: A hairless achene, pappus of unbranched hairs.
Habitat: Marshes, lake shores, damp grassland; occasionally on roadsides or dry grassland.
Distribution: Abundant on acid soils, fairly frequent in the Burren, rare around Galway Bay.
Native status: Native
Of conservation interest: No