Xyris involucrata
Content
Description
Short-lived, mostly tufted, smoothish herbs, 20-60 cm high; stem short. Leaves in a fan, 10-30 cm, sheath at least as long as blade, entire, keeled, base castaneous, ligule lacking, blade flattened, margins white-ciliate. Scapes rigid, distally flattened, 3-4 mm wide, margins winged, white-ciliate; spikes hemispheric to broadly ovoid or subglobose, 0.5-1 cm, bracts numerous in a tight spiral, outer ones forming a leafy involucre, these bracts with keel and margins ciliate, inner empty bracts abruptly smaller, grading to slightly shorter flowering bracts, these firm, rhombic to oblong-obovate, 4-5 mm, tips acute or short-acuminate, often villosulous, back shallowly convex with a large, red-brown dorsal area. Lateral sepals free, subequilateral, curved, ca. 3 mm, blunt, keel reddish-ciliate from below middle to apex; petals elliptic, 4-5 mm; staminodes bearded; anthers ca. 1.5 mm. Capsule ca. 2 mm, placentation basal, valves eseptate; seeds ellipsoid-cylindric, 0.5-0.6 mm, dark amber.
Distribution
Guyana present, S Venezuela present, SE Colombia present, contiguous Brazil present
SE Colombia E through S Venezuela to Guyana and in contiguous Brazil.
Notes
The only species of Xyris in the Guianas to have a spreading invo- lucre of leafy bracts to twice as long as the heads are wide, and actually a part of a leafy-bracted complex more typical of the Brazilian Planalto. Unusual for most Xyris of northern South America but characteristic for this complex, many corollas are presented simultaneously on a spike, thus contributing much to the attractiveness of such plants.