Xyris guianensis
Content
Description
Low, cespitose, smooth, annual 5-30 cm high. Leaves in a fan, 2.5-7 cm, often maroon or red-brown, about as long as scape sheath, sheath about half as long as blade or less, keel often papillose-ciliolate, margin entire, continuous with blade or with auricles, blade flattened, 0.5-1 mm wide, margins narrow, incrassate, pale or dark, smooth or rarely ciliolate. Scapes filiform, distally terete or slightly compressed, ca. 0.5 mm thick, ecostate to slightly bicostate, ribs smooth; spikes ellipsoid becoming turbinate, 4-7 mm, pale red-brown, bracts few, decussate, with strong lance-ovate dorsal area with strong midvein, empty bracts 4, smaller and narrower than the flowering ones and grading into them, these oblong 4.5-5 mm, less keeled, subacute, scarious-margined. Lateral sepals free, subequilateral, oblanceolate4-5 mm, keel smooth or papillose to ciliolate above middle; petals obovate, ca. 3 mm; staminodes bearded; anthers ca. 1 mm. Capsule ca. 2.5 mm, placentation basal-central, valves eseptate; seeds ovoid to ellipsoid, ca. 0.5 mm, amber.
Distribution
S Colombia present, S Venezuela present, Suriname present, to Goias? present
S Colombia E across S Venezuela to Suriname and in contiguous Brazil (to Goias?)
Notes
This is one of many small species of Xyris that abound in sand savanna at low to high elevations in northern South America, usually in association with such others as X. paraensis , X. savanensis , and X. uleana . Through the range, but more often west, in T.F. Amazonas, Venezuela and in Vaupes, Colombia, as well as in Amazonian Brazil is a more slender-leaved extreme named X. filiscapa but its type differs in no significant way. Some confusion perhaps arises because of another diminutive xyrid, X. tenella , much of which has been identified as X. filiscapa , but which differs in its long-ciliate leaf sheath and its streak-like dorsal area.