An Illustrated Guide to ARIZONA WEEDS

The University of Arizona Press




ROCKY MOUNTAIN IRIS-Iris missouriensis Nutt.

DESCRIPTION-A perennial, 1 to 2 1/2 feet high, reproducing from seeds and from dark reddish thick woody rhizomes, mostly horizontal and branching, bearing many stout roots. The long narrow bluish green leaves in clusters at the base of the flower stems are 2-ranked, flat or folded lengthwise, and enfolding one another, l/3 to 2 feet long, and l/8 to 3/8 inch broad.

The flowering stems are 1 to 2 1/2 feet high, usually leafless or with an occasional small leaf, bearing 2 to several flowers, one flower blossoming after another. The large sweet smelling flowers are pale blue or violet, about 3 inches in diameter, and 3 to 4 inches long. The base of the flowers is enclosed by a pair of bracts, leaflike at first, becoming thin and dryish, 1 1/2 to 3 inches long. The 3 outer parts of the flower curve downward, and are longer than the 3 inner erect petals. The 3 branches of the style are large, colored similar to the petals, and spread outwardly covering the 3 stamens.

The large oblong seedpods, 1 to 1 1/2 inches long, 1/2 to 3/4 inch thick, are 3-celled, with many seeds, usually in 2 rows in each cell. The dark reddish brown seeds are somewhat wedgeshaped, with irregular depressions and ridges, or D-shaped and plump, 1/8 to l/4 inch long.

DISTRIBUTION-Rocky Mountain iris is a native range weed of wet soil and high elevations. It is common on the high plateaus, open mountain meadows, near springs, in wet barren flats, or other places more or less denuded of vegetation. It becomes more common on overgrazed, deteriorated ranges. Found in Navajo, Apache, and Coconino counties, and in the mountains of southeastern Arizona 6,000 to 9,500 feet elevation; flowering May to September.

Copyright (c) 1972 The Arizona Board of Regents

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