Two other small plants growing in muddy places and often submerged are Mimulus repens and Limosella tenuifolia (mudwort), relatives of the monkeymusk (Mimulus guttatis). Some species of buttercup of similar habitat are Ranunculus rivularis (poisonous to stock), R. fluitans, and R. macropus. Also growing in wet mud, completely submerged at times, are Callitriche verna, the light green starwort; Elatine gratioloides, which creeps under water at edges of lakes; Ludwigia palustris, water purslane, with a mat-like form of reddish colour; and Tillaea sinclairii, found mainly in the South Island. These are all tiny plants. More conspicuous are sedges and rushes. Of many species of Carex a few grow near the edges of water. The genus Scirpus includes species from 3–10 ft high of which the best known are S. lacustris, our tallest sedge, common throughout the country; S. perviridis, usually 5–6 ft, of the North Island, and the shorter S. caldwellii, found in both Islands. Species of Eleocharis and of Cladium are other familiar sedges. The raupo, Typha muellerii, known to the Maoris as koreire, is probably the best known of our plants of watery swamps. Before there was any systematic drainage of the country, extensive areas were covered by raupo. The tall flower stalks have dense masses of tiny flowers, male flowers above and female flowers on the lower part. This plant was useful to the Maoris in various ways: the rhizomes for food, the flower heads and hairy fruits for plugging holes in canoes, and pollen mixed with water baked as cakes. Early settlers used inflorescences for stuffing pillows and beds and the leaves for thatching roofs.