Xyris difformis, the bog yelloweyed grass, is a North American species of flowering plant in the yellow-eyed-grass family. It is native to the eastern and southern United States, eastern and central Canada, and Central America.

Xyris difformis is a perennial herb up to 90 cm (3 feet) tall with grass-like leaves up to 50 cm (20 inches) long, and yellow flowers.

Varieties

• Xyris difformis var. curtissii (Malme) Kral - Belize, coastal states of USA from Texas to Virginia
• Xyris difformis var. difformis - Nova Scotia, Ontario, USA (coastal states from Maine to Texas plus areas as far inland as Michigan, Oklahoma, Indiana, and Arkansas)
• Xyris difformis var. floridana Kral - Belize, Honduras, Nicaragua, USA (coastal states from Louisiana to the Carolinas)

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