Poaceae groups, using the C3 and C4 photosynthetic pathways for carbon fixation. The C4 grasses have a photosynthetic pathway, linked to specialized Kranz leaf anatomy, which allows for increased water use efficiency, rendering them better adapted to hot, arid environments and those lacking in carbon dioxide. The C3 grasses are referred to as "cool-season" grasses, while the C4 plants are considered "warm-season" grasses. The grass family is one of the most widely distributed and abundant groups of plants on Earth. Grasses are found on every continent, including Antarctica with the presence of Antarctic hair grass on the Antarctic Peninsula. Grasses are
Organisms involved in water purification and to generate toxins in some cases. The choice of organism depends on the local climate different species and other factors. Indigenous species usually tend to be better adapted to the local environment. The choice of plants in engineered wet-lands or managed lagoons is dependent on the purification requirements of the system and this may involve plantings of varying plant species at a range of depths to achieve the required goal. Plants purify water by consuming excess nutrients and by providing surfaces upon which a wide range of other purifying organisms can live. They also are effective oxygenators in sunlight.