Appearance
Bromus tectorum is an erect-stemmed annual grass that grows to about 8-25 in. (20-70 cm) in height.

Foliage
The leaf sheaths and blades are covered with soft short hairs. The leaves are 0.08-0.16 in. (2-4 mm) wide and up to 8 in. (20 cm) long. Its ligules are 0.04-0.1 in. (1-2.5 mm) long.

Flowers
The panicles measure 2-7.75 in. (5-20 cm) long, have numerous branches, retain an open quality, and are generally nodding. The panicles bear from 3 to 8 drooping spikelets, each spikelet is 0.8-1.4 in. (2-3.5 cm) long. The glumes are awl-shaped. The lemmas are narrowly lanceolate, 0.04-0.06 in. (1-1.5 mm) wide, toothed, and sometimes hairy. They have slender, straight awns that are 0.4-0.67 in. (10-17 mm) long. Flowering occurs from May to June.

Fruit
The seeds can germinate in the fall or in the spring; fall germination is generally more common. B. tectorum has a fibrous root system that is finely divided. When a seed germinates in the fall, the developing root system is able to expand over the winter, giving the plant an increased ability to exploit available water and nutrients in the spring.

Ecological Threat
Bromus tectorum has the ability to draw down soil moisture and nutrients to very low levels, making it difficult for other species to compete. An increased cycle of fires favors annual species at the expense of many perennials. Due to its tendency to mature early and then dry out, it gains a competitive advantage through the promotion of fire. It is an agricultural, nursery, and orchard pest.

Resources

• Element Stewardship Abstract - The Nature Conservancy
• Weed of the Week - USDA Forest Service
• Weed Field Guide - USDA Forest Service

Selected Images

Maps

Invasive Listing Sources

• Alberta Weed Control Act
• California Invasive Plant Council
• Colorado Noxious Weeds
• Commonwealth of Pennsylvania, Department of Conservation and Natural Resources, 1994.
• Connecticut Invasive Plant List
• Connecticut Invasive Plant Working Group
• Connecticut Noxious Weeds
• Georgia Exotic Pest Plant Council - Category 4
• Invasive Plant Species of West Virginia
• Jil M. Swearingen, Survey of invasive plants occurring on National Park Service lands, 2000-2007
• John Randall, The Nature Conservancy, Survey of TNC Preserves, 1995.
• Kentucky Exotic Pest Plant Council - Significant Threat
• Montana Noxious Weeds
• National Park Service, Mid-Atlantic Exotic Plant Management Team Invasive Plant List
• Native Plant Society of Oregon, 2008
• New Hampshire Invasive Plant Species Watch List
• New Mexico Noxious Weeds
• Nonnative Invasive Species in Southern Forest and Grassland Ecosystems
• Pennsylvania Department of Conservation and Natural Resources Invasive Plants
• WeedUS - Database of Plants Invading Natural Areas in the United States
• West Virginia Invasive Species Strategic Plan and Volunteer Guidelines 2014
• West Virginia Native Plant Society, Flora West Virginia Project, and West Virginia Curatorial Database System, September 3, 1999

References