More slender in every way than Iris versicolor Linnaeus, with a tuberous-thickened rootstock; stem 1 to 3 feet tall, bearing two or three very narrow, almost grasslike leaves usually less than one-fourth of an inch wide; flowers one or two at summit of each stem, blue, veined with yellow on slender pedicels; outer perianth segments one-half to 2 inches long, smooth and devoid of a crest, the inner segments smaller and narrower; the perianth tube about one-fourth of an inch long above the ovary. Fruit a narrowly oblong capsule, acute at each end and sharply three-angled, 1 to 1 inches long.

Marshes, wet meadows and swamps, mainly near the coast from Nova. Scotia to Pennsylvania and Georgia. Flowering in May and June.

Memoir 15 N. Y. State Museum

Plate 27

Narrow Blue Flag; Poison Flagroot

Narrow Blue Flag; Poison Flagroot - Iris prismatica