Coastal Plain Yellow Eyed Grass

Xyris ambigua is one of the more widespread and weedy of xyrids, frequently invading disturbed moist, sandy areas. It is also one of the most variable in habit and apparently forms intermediates with X. stricta and X. torta.

Herbs, perennial, cespitose or solitary, 30--100 cm. Leaves in broad or narrow fans, (5--)10--40(--50) cm; sheath base tan, straw-colored, or pale pink; blade pale or olive green, linear-triangular, (2--)3--7(--10) mm wide, smooth or slightly papillate, margins smooth to minutely scabrous or papillate. Inflorescences: scape sheaths much exceeded by leaves; scapes linear, rarely flexuous, terete or nearly terete, 1--1.5 mm wide, distally usually 2-ribbed, sometimes with additional ribs; spikes ovoid to ellipsoid, lanceoloid, or cylindric, 10--20(--30) mm; fertile bracts 5--8 mm, margins entire, apex rounded. Flowers: lateral sepals included, dark brown, strongly curved, 4--7 mm, keel firm, ciliate, petals unfolding in morning, blade obovate, 10 mm; staminodes bearded. Seeds translucent, ovoid to ellipsoid, 0.5--0.6 mm, finely multiribbed and cross ribbed. 2n = 18.

Ala., Ark., Fla., Ga., La., Miss., N.C., S.C., Tenn., Tex., Va.; Mexico; West Indies (Cuba); Mexico; Central America (Belize, Honduras, Nicaragua).

Flowering late spring--fall (all year south).

Acid, sandy, moist pine or oak savanna, pine flatwoods, pond shores, ditches, bogs; 0--300m.

Xyris ambigua Beyr.; Kunth, Enum. PI. 4: 13. 1843
Xyris stricta Chapm. Fl. S. U. S. 500. 1860.
Xyris rhombipetala Wright fSauv. Anal. Acad. Ci. Habana 7: 611. 1871.
Tall, tufted; leaves linear, 15-30 (-40) cm. long, 3-5 (-6) mm. broad, somewhat obtuse at the apex, scabrid or rarely smooth on the margins, elsewhere smooth; sheath occupying about one half the length of the leaf, somewhat dilated and opaque below, pale-rusty at base ; peduncles 50-90 cm. tall, 1.5-2 mm. broad, nearly terete, bicostate above, multistriate or multicostate below, scabrid on the ridges, elsewhere smooth, the peduncular sheath 10-15 (-20) cm long, rusty and shining below; spike many-flowered, ellipsoid or ovoid, 10-20 (-25) mm. long, 5-6 (-7) mm. thick, the outer barren bracts 2-2.5 mm. long, ovate-deltoid, acute or somewhat obtuse, the flowering bracts obovate-elliptic, 7-8.5 mm. long, .5-6 mm. broad, rounded, entire or somewhat lacerate at the apex, straw-colored, tawny, or pale-rusty, somewhat shining, with a deltoid or ovate dorsal area about 2 mm. long; lateral sepals lanceolate, about 6 mm. long and 1.5 mm. broad, acute at the apex; keel broad, especially at the middle, ciliate-scabrid from about the middle to the apex; seeds ellipsoid, 0.4-0.5 mm. long.
Typb locality: Margins of swamps, Georgia.
DISTRIBUTION: North Carolina to Florida and Texas; Cuba (Pinar del RioJ and Isla de Pifios; British Honduras

Xyris ambigua, the coastal plain yelloweyed grass, is a North American species of flowering plant in the yellow-eyed-grass family. It is native to southern and eastern Mexico (Tamaulipas, Veracruz, Tabasco, Chiapas, the Yucatán), Central America (Belize, Honduras, Nicaragua), Cuba, and the southeastern and south-central United States (from Texas to Virginia inland to Tennessee and Arkansas).

Xyris ambigua is a perennial herb up to 100 cm (40 inches) tall with grass-like leaves and yellow flowers.