Genus of 5-6 varieties of tufted, rhizomatous and tuberous, evergreen or semi-evergreen perennials, seen in usually acidic woodland environments in China, Vietnam, Taiwan, and China. They have arching, linear, lawn-like significant leaves, creating dense sections or mats. Modest, ovoid to spherical flowers, opening up only slightly, are clustered in short, dense spikes or racemes, and so are followed by black fruits.