Epiphytic, occasionally lithophytic,
herbs with monopodial growth. Stem covered with old leaf
bases. Roots numerous, arising along stem, often with
prominent white streaks. Pseudobulbs 0. Leaves distichous. Flowers
translucent, usually white, yellowish or greenish, less often
pinkish or purplish. Sepals and petals free. Lip entire or
obscurely lobed; margin often erose. Pollinia 2.