Zamioculcas zamiifolia 'Dowon' Raven ZZ plant features dark, purple-black foliage that contrasts other houseplants. It grows about 30 inches (76 cm) tall and wide. This patented variety is exclusively grown in North America by Costa Farms. Like many indoor plants, Zamioculas can improve the quality of air in an indoor space. But unlike others, he can also improve human health in these spaces, as it's recently been found that he can remove carcinogens, such as Benzene, that are often found in a home.