Spathiphyllum is a genus of about 47 species of monocotyledonous flowering plants in the family Araceae, native to tropical regions of the Americas and southeastern Asia. Certain species of Spathiphyllum are commonly known as spath or peace lilies. They are evergreen herbaceous perennial plants with large leaves 12–65 cm long and 3–25 cm broad. The flowers are produced in a spadix, surrounded by a 10–30 cm long, white, yellowish, or greenish spathe. The plant does not need large amounts of light or water to survive. They are most often grown as houseplants, however they are able to withstand the elements well enough to thrive when planted outdoors in situations that are hot and humid. Etymology Schott's description of the genus refers to , where is a spathe, and is an adjective modifying spathe, meaning relating to a leaf, and means continuing or persisting. also means a leaf. The more common name of peace lily derives from the plants symbolism for peace, purity, and healing, and has also been associated with the white flag, which is a signal for truce. Selected species Species include: Spathiphyllum atrovirens Spathiphyllum bariense Spathiphyllum blandum Spathiphyllum brevirostre Spathiphyllum cannifolium Spathiphyllum cochlearispathum Spathiphyllum commutatum Spathiphyllum cuspidatum Spathiphyllum floribundum Spathiphyllum friedrichsthalii Spathiphyllum fulvovirens Spathiphyllum gardneri Spathiphyllum grandifolium Spathiphyllum jejunum Spathiphyllum juninense Spathiphyllum kalbreyeri Spathiphyllum kochii Spathiphyllum laeve Spathiphyllum lechlerianum Spathiphyllum maguirei Spathiphyllum mawarinumae Spathiphyllum monachinoi Spathiphyllum montanum Spathiphyllum neblinae Spathiphyllum ortgiesii Spathiphyllum patini Spathiphyllum perezii Spathiphyllum phryniifolium Spathiphyllum quindiuense Spathiphyllum silvicola Spathiphyllum solomonense Spathiphyllum wallisii Spathiphyllum wendlandii Cultivated hybrids include: Spathiphyllum × clevelandii Cultivation and uses Several species are popular indoor houseplants. It lives best in shade and needs little sunlight to thrive, and is watered approximately once a week. The soil is best left moist but only needs watering if the soil is dry. The NASA Clean Air Study found that Spathiphyllum cleans certain gaseous environmental contaminants, including benzene and formaldehyde. However, subsequent tests have shown this cleaning effect is far too small to be practical. The cultivar 'Mauna Loa' has won the Royal Horticultural Society's Award of Garden Merit. Toxicity Although it is called a "lily", the peace lily is not a true lily from the family Liliaceae. True lilies are highly toxic (poisonous) to cats and dogs, but the peace lily, spathiphyllum is only mildly toxic to humans and other animals when ingested. It contains calcium oxalate crystals, which can cause skin irritation, a burning