An Illustrated Guide to ARIZONA WEEDS

The University of Arizona Press




POVERTYWEED-Iva axillaris Pursh

DESCRIPTION-Povertyweed is a rank smelling, very leafy, bushy perennial, usually growing in colonies, and reproducing by creeping roots, erect roots, and seed. The slender stems, branching from the base, are 1/2 to 2 feet high. The small, thick, stalkless leaves, opposite below and alternate above, are oblong, 1/2 to 1 1/2 inches long, and grow to the tip of the branches.

Small drooping flower heads enclosed by a green cup hang downward from short stalks. They are composed of tiny flowers; the outer 5 are fertile and female; the inner 10 to 25 are sterile and male. The heads occur singly in the leaf axils on the upper half of the stems, and each produces 5 fruits. The brown, topshaped, granular achenes, 1/12 to 1/8 inch long, are beaked at first.

DISTRIBUTION-Povertyweed is a native plant, preferring alkaline soil. It has become a pest in grain fields, other crops, flats, and waste places in many areas in northern Arizona (e.g. Woodruff, Show Low, Tuba, Pumkin Center, Fredonia), in Apache, Navajo, and Coconino counties; 4,000 to 7,500 feet elevation; flowering May to September. Once this weed becomes established, it may spread at an alarming rate.

MARSHELDER-Iva xanthifolia Nutt.

DESCRIPTION-A tall robust annual, 2 to 6 feet or more high, reproducing by seeds. The long stalked, large leaves, mostly opposite are 3 to 12 inches long, and similar to those of the cocklebur. The flowers arc like those of povertyweed, but here the flower heads are stalkless, and are crowded on long branching spikes at the top of the stems and the upper leaf bases. The flowering part of the plant may be greatly branched and spreading, and I to 2 feet or more long. The achenes are blacker than those of povertyweed, and not granular, but otherwise similar.

Marshelder grows in moist soil along streams, roadsides, and waste places in northern Arizona, and is also an infrequent garden weed in the Phoenix area in Apache, Navajo, Yavapai, and Maricopa counties; 1,000 to 6,500 feet elevation; flowering July to October. The pollen may cause serious hay fever, and the leaves produce a skin rash in some people. Fortunately, it isn't very widespread in Arizona.

Copyright (c) 1972 The Arizona Board of Regents

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