Rhizomatous, prostrate perennial herb rooting at the nodes. Leaves to 5 cm long, narrowly obovate to spoon-shaped, entire or wavy-toothed, more or less hairless. Flower clusters of up to 6 flowers. Calyx with narrow, pointed lobes. Petals white or blue, with a yellow throat. Fruit capsule almost round, the calyx persistent.
M. radicans (Hook. F.) Cheesem. from New Zealand has white flowers with a yellow throat, the lips sometimes mottled with purple, while M. reptans N.E. Br. from the Himalaya has violet-blue flowers (white in the cultivar 'Albus') with the lower lip mottled with yellow, white and mauve.
Source: (2002). Scrophulariaceae. In: . Horticultural Flora of South-eastern Australia. Volume 4. Flowering plants. Dicotyledons. Part 3. The identification of garden and cultivated plants. University of New South Wales Press.