18. Oserya Tulasne & Weddell
Oserya Tulasne & Weddell, Ann. Sci. Nat. Bot. III, 11: 105 (1849).
Roots thread-like, often becoming flattened when old, branched; stems short, developing at almost regular intervals along sides of root, usually in opposite or subopposite pairs. Leaf sheaths simple or double; petioles cylindrical or flattened; blades simple or repeatedly forked with filamentous ultimate segments, inrolled when young. Spathellas club-shaped, slightly exceeding base, opening irregularly. Flowers solitary, terminating the stem or several in leaf axils; pedicels 0.1--0.8 (1.4) cm long; tepals (2) 3, when stamens 2 then one each side of the stamen and the third on back of the fork of filaments or rarely absent; stamens (1) 2 (3), when stamens 2 then usually united below into short andropodium; anthers basifixed, introrse in Mexican spp., or extrorse in South American spp.; pollen in monads. Capsules ovoid; valves equal (Mexico) or unequal (South America) with oblique and acentric sutures, the larger one persistent, with 3--13 ribs; stigmas very short. Seeds up to ± 80. Six spp. Mexico, northern South America & C Brazil.