caulescent, sometimes acaulescent herbs, not aromatic, rhizomes tuberous.
Leaves simple, spirally arranged, petiole short, closed, blade with a prominent
midrib and numerous lateral veins, entire and rolled in bud. Inflorescence a
dense head or spike, terminal, bracteate. Flowers bisexual, zygomorphic. Sepals 3, tubular below, lobes
short. Petals 3, unequal, connate below, lobes convolute. Stamens 6, in 2
cycles of 3, median of inner cycle functional, other 2 sterile forming a
petaloid labellum in conjunction with the 3 of outer cycle. Carpels 3, ovary
3-locular, placentation axile, or 2-locular
placentation parietal. Fruit capsule, crowned by persistent calyx. Seeds
arilate, embryo straight.