Dymondia margaretae is an evergreen perennial, 50 mm high and with a creeping, much-branched rhizome, at or just below the surface. It is fast-growing, forming a dense, spreading, flat mat of growth, which completely covers the surface. Blue-grey, basal leaf rosettes are borne on short erect shoots from the rhizome. The leaves are small, rigid and thick, linear-oblanceolate (narrowly lance-shaped with the broadest part above the middle), with 2-3 shallow, obtuse teeth on each side. Leaf margins are slightly incurved showing the pale, felt-like undersides. The upper leaf surface is dark green and glabrous (hairless).