Acanthus blossoms, drying like immortelles, “bloom continually” (Hellanicus, ap. Athen. XV, 680 a). Therefore carved acanthus garlands adorn the Erechtheum, while the plant is carved on cymae, stelae-acroteria (Conze, Attische Grabreliefs, pl. clxv) and antefixes (Lycian Payava Tomb), and is sketched from life on white Athenian lecythi (Brit. Mus. Coll. pl. xiv), which, conventionalized, it constantly encircles.
Source: wiktionary