Cottonweed

Achillea maritima, long known as Otanthus maritimus and commonly called cottonweed or sea cudweed, is a small pioneering perennial herb of the daisy family Asteraceae. The whole plant is densely cloaked in a thick white woolly tomentum that gives the foliage a striking silvery-felt appearance and helps it tolerate salt spray and drying winds. It forms low spreading mats of branched, ascending stems 10 to 30 cm tall, with small, alternate, oval, slightly saw-toothed leaves crowded along the shoots. From June to September the plant produces dense terminal clusters of globose flower heads enclosed by white-woolly scales surrounding small tubular yellow florets; the corolla forms three membranous, ear-like bracts that gave the former genus its name Otanthus, from Greek otos (ear) and anthos (flower). Native to coastal dune systems throughout the Mediterranean region and parts of the Atlantic European seaboard, it stabilises sandy soils as a pioneer colonist and has declined sharply in many areas due to coastal development.