Perennial pepperweed Lepidium latifolium Steve Dewey, Utah State

Perennial pepperweed Lepidium latifolium Steve Dewey, Utah State University; Leslie J. Mehrhoff, University of Connecticut, Bugwood.org A 1 3 foot tall perennial with waxy leaves, white flowers, and creeping rhizomes. Also known as tall whitetop. Impacts riparian areas and wetlands by forming large dense stands that displace native plants.

Purple loosestrife Lythrum salicaria Linda Wilson, University of Idaho, Bugwood.org A 8 foot tall semi-aquatic perennial with long, showy, rose-purple flower spikes and square stems. Impacts wetland ecosystems by forming dense stands that displace native plants The Thistles Chris Evans, River to River CWMA, Bugwood.org

Forest & Kim Starr, United States Geological Survey, Bugwood.org Steve Dewey, Utah State University, Bugwood.org Mary Ellen (Mel) Harte, , Bugwood.org Musk Bull Scotch Canada Cardus nutans Cirsium

vulgare Onopordium acanthum Cirsium arvense Scotch thistle Onopordum acanthium Eric Coombs, Oregon Dept. of Agriculture A 4-8 foot tall annual with purple flower heads and spine tipped stems and leaves. Plants thrive in disturbed areas and

can quickly become the dominant vegetation if left Canada thistle Cirsium arvense Steve Dewey, Utah State University; Theodore Webster, USDA Ag Research Service, Bugwood.org A 1 - 4 foot tall perennial with small purple flowers and prickly leaves. Impacts a wide range of habitats including cropland and riparian areas. Creeping rhizomes can colonize an

area 3 - 6 feet in diameter in just a few years. Field Bindweed Convolvulus arvensis A twining perennial with white, trumpet-shaped flowers. Impacts a wide variety of habitats including agriculture and home landscapes. Control is often difficult because plants reproduce vegetatively from roots, rhizomes, stem fragments, and by

seeds that can lie dormant in the soil for up Puncturevine Tribulus terrestris A yellow flowering annual that forms dense mats and hard, spiky seed cases that can injure livestock, people, and pets. Longterm control of puncturevine can be achieved by consistently reducing the amount of seed in Garlic mustard

Alliaria petiolata Leslie J. Mehrhoff, University of Connecticut, Bugwood.org A 3 foot tall biennial herb with self pollinating white flowers. All plant parts have a distinctive garlic odor when crushed. Impacts forested communities by altering the soil and out Myrtle spurge Euphorbia myrsinites Patrick Nelson, Cottonwood Canyons Foundation

An escaped ornamental containing a caustic sap that can result in skin irritation and swelling. Grows in a range of habitats from shaded oak under stories to sunny slopes.