Identifying Grass Weeds

Stem/culm

Node

Leaf

Sheath

Collar

Blade

Midrib

Vernation

Vernation is a term used to describe how the youngest grass leaves are arranged in the shoot

Folded vernation Leaves that are folded in the shoot and appear V-

shaped in shoots that are cut in half across the width (cross-sectioned)

Rolled vernation Leaves are circular or “rolled" in the shoot and do

not have folds

Determining vernation: Roll test

Cross-section

Ligules and Auricles

Ligules are membranous or hairy tissues located at the junction of the leaf blade and leaf sheath

Ligules can be membranous, a fringe of hairs, or absent

Auricles are slender extensions of the collar and are located at the junction of the leaf blade and leaf sheath

Auricles can be long and clasp around the stem or shoot, small or rudimentary, or absent

Growth habit and inflorescence (seed head)

Panicle Spike Raceme

Rhizomatous Bunch Stoloniferous

Green foxtail Scientific name: Setaria viridis

Family: Poaceae

Life cycle: Annual

Where found: Cropland

Physical description:

Seed: 1-2 mm, pale lemma covering seed

Seedling blade: broad and arched

Leaf blades mostly hairless

Vernation: round

Ligule: hairy

Inflorescence: compact panicle

Fibrous root system

Interesting facts:

Latin name describes inflorescence

Seta=bristle, viridis=green

Also called green bristlegrass

Jointed goatgrass Scientific name: Aegilops cyclindra

Family: Poaceae

Life cycle: Annual

Where found: Cropland

Physical description: Seed: attaches firmly to lemma and palea at each

joint

Seedling blade: first blade tall, narrow and vertical

Leaf blades with long hairs on margins of blade and collar

Vernation: round

Ligule: membranous with toothed margin

Inflorescence: columnar spikelet with distinctive joints

Fibrous root system

Interesting facts: May behave as a winter annual in some areas

Known to hybridize with wheat

Quackgrass Scientific name: Agropyron repens (aka Elytrigia repens)

Family: Poaceae

Life cycle: Perennial

Where found: Range, Cropland

Physical description:

Seed: resemble wheat; slender, elongate, tan

Seedling blade: first blade tall, narrow and vertical

Leaf blades mostly hairless, often constricted at the tip

Vernation: round

Ligule: short, membranous

Clasping auricle

Inflorescence: spike

Aggressive, rhizomatous root system

Interesting facts:

Latin name describes resemblance to wheat and creeping root systems

Agropyron=wild wheat; repens=creeping

Also called couchgrass

Wild oat Scientific name: Avena fatua

Family: Poaceae

Life cycle: Annual

Where found: Cropland

Physical description:

Seed: long with twisted awn attached to lemma

Seedling blade: first blade tall, narrow, vertical

Older leaf blades have long hairs on margins of blade and collar; stems nearly hairless

Vernation: round

Ligule: membranous, tall, slightly toothed

Inflorescence: open panicle with drooping spikelets

Fibrous root system

Interesting facts:

Awn helps plants twist into the soil

Twisted when dry, straightens when wet

Plant may grow 4 feet tall