Ohio State University Extension Bulletin

Corn, Soybean, Wheat, and Alfalfa Field Guide

Bulletin 827-05

WEED MANAGEMENT

Grass and Grasslike weed vegetative key.

ANNUAL GRASS WEEDS

FALL PANICUM
(Panicum dichotomiflorum)
	Sheath: slightly flattened, smooth to occasionally hairy Blade: smooth, dull above & glossy below, underside may have hair Ligule: fringe of hairs Auricles: absent

SMOOTH CRABGRASS
(Digitaria ischaemum)
	Sheath: flattened & smooth, smooth margin Blade: long hairs near ligule, rough margin Ligule: long, membranous, rounded Auricles: absent

LARGE CRABGRASS
(Digitaria sanguinalis)
	Sheath: flattened with longscattered hairs Blade: sparse hairs above & below Ligule: membranous with notched margins Auricles: absent

BARNYARDGRASS
(Echinochloa crus-galli)
	Sheath: smooth & flattened Blade: rough margin, prominent mid-vein Ligule: absent Auricles: absent

WITCHGRASS
(Panicum capillare)
	Sheath: slightly flat, densely hairy Ligule: short fringe of hairs Blade: densely hairy above and below. Auricles: absent

SHATTERCANE
(Sorghum bicolor)
	Sheath: rounded and smooth Ligule: long, membranous, rounded. May be jagged or ciliated. Blade: smooth but occasionally sparse hairs above Auricles: absent

GIANT FOXTAIL
(Setaria faberi)
	Sheath: round, hair on margin Blade: short hairs covering upper surface Ligule: fringe of hairs Auricles: absent

YELLOW FOXTAIL
(Setaria glauca)
	Sheath: flat, smooth margins Blade: few long hairs near base Ligule: fringe of hairs Auricles: absent

GREEN FOXTAIL
(Setaria viridis)
	Sheath: round, hair on margins Blade: hairless Ligule: fringe of hairs Auricles: absent

PERENNIAL GRASS WEEDS

WIRESTEM MUHLY
(Muhlenbergia frondosa)
	BSheath: flattened, smooth Ligule: short, membranous, toothed margins Blade: rough above, below, and on margins Auricles: absent

QUACKGRASS
(Elytrigia repens)
	Sheath: rounded, smooth to sparsely hairy Blade: rough above, below, & on margins Ligule: short, membranous Auricles: long, slender, clasping

JOHNSONGRASS
(Sorghum halepense)
	Sheath: rounded to flattened, smooth Blade: smooth to sparsely hairy above and smooth below Ligule: ong, rounded, possibly ciliated

SUMMER ANNUAL BROADLEAF WEEDS

COMMON COCKLEBUR
(Xanthium strumarium)
		Cotyledon: lanceolate, waxy & dark green. Leaf: rough, triangular, with slightly lobed margin. First leaves are opposite, others are alternate. Stem: erect, ridged, rough, hairy, and purple-spotted.

COMMON LAMBSQUARTERS
(Chenopodium album)
		Cotyledon: small but linear. Leaf: white mealy-coating both above and below, especially on young leaves. First true leaves are opposite, others are alternate with triangular shape and serrated. Stem: erect, smooth, grooved, strong and sometimes purple at the nodes.

PRICKLY LETTUCE
(Lactuca serriola)
		Cotyledon: spatulate with slight indentation at tip, hairy. Leaf: prickly spines along underside of midrib, first leaves are spatulate, later becoming deeply lobed with weak spines, hairy. Stem: hollow with a milky juice.

JIMSONWEED
(Datura stramonium)
		Cotyledon: smooth and lanceolate, whole seedling plant has a pungent odor when crushed. Leaf: smooth, waxy, multipointed margins. Stem: hairy hypocotyl ,smooth and tough.

IVYLEAF MORNINGGLORY
(Ipomoea hederacea)
		Cotyledon: smooth, shiny, and butterfly shaped. Leaf: alternate, tall and upright hairs, on both sides, 3-lobed giving an ivy shape. Stem: thin, hairy, vine-like.

TALL MORNINGGLORY
(Ipomoea purpurea)
		Cotyledon: smooth, shiny and butterfly shaped. Leaf: alternate, dense, short appressed hairs on both sides, although less below, and broadly heart-shaped. Stem: thin, dense, very short hairs, vine-like.

WILD MUSTARD
(Brassica kaber)
		Cotyledon: kidney-shaped and smooth. Leaf: alternate and hairy, lower leaves are lobed, have petioles and vary in size and shape, upper leaves are smaller, have no petioles and are not as lobed and irregular. Stem: hairy near base. Other: four yellow petals on flowers.

EASTERN BLACK NIGHTSHADE
(Solanum ptycanthum)
		Cotyledon: small, ovate, green both surfaces. Leaf: waxy appearance on top, purple below, some hair and small lobes. Stem: erect, smooth, fleshy, weak.

REDROOT PIGWEED
(Amaranthus retroflexus)
		Cotyledon: linear, hairless. Leaf: alternate, slightly notched/indented at tip. Stem: erect, short hairs, red to purplish color on stems and petiole.

COMMON RAGWEED
(Ambrosia artemisifolia)
		Cotyledon: oval to spatulate with grooved petioles, and purple undersides. Leaf: lots of variation, lacy appearance, sometimes hairy below, smooth above, opposite early but turning alternate.

GIANT RAGWEED
(Ambrosia trifida)
		Cotyledon: oval to spatulate with grooved petioles, similar to common ragweed cotyledons but three to four times larger, with green undersides instead of purple. Leaf: rough, hairy, deeply lobed - 3 to 5 lobes, sometimes with no lobes, opposite early but turning alternate. Stem: erect, rough, hairy.

PENNSYLVANIA SMARTWEED
(Polygonum pennsylvanicum)
		Cotyledon: lanceolate with rounded tips. Leaf: alternate, smooth edges, may or may not have purple thumbprint. Stem: erect, smooth, ocrea at base of petiole, no hair on ochrea.

VELVETLEAF
		Cotyledon: one round and one heart-shaped cotyledon, both hairy. Leaf: densely hairy (possessing a velvety texture), heart shaped. Stem: erect, densely hairy.

COMMON/TALL WATERHEMP
(Amaranthus rudis/tuberculatus)
	Cotyledon: linear and hairless. Leaf: alternate, no hair, leaf is longer than it is wide making it more linear than pigweeds, usually a wavy leaf margin, and no notch at tip. Stem: erect, no hair, and varying color from green to red.

WINTER ANNUAL BROADLEAF WEEDS

COMMON CHICKWEED
(Stellaria media)
		Cotyledon: broadly ovate, pale green. Leaf: hairless, small, pale green, pointed at tip. Stem: erect, stems & petioles sparsely hairy, hypocotyl red.

PURPLE DEADNETTLE
(Lamium purpureum)
	Cotyledon: round to square, no hair, petiole shorter than henbit, a white point at tip, cotyledon lobes at petiole usually touch each other. Leaf: opposite, twice the amount and length of hair compared to henbit, serrated leaf margin, leaves always have petioles, round to triangular shaped leaves. Stem: erect to prostrate, square, twice the amount and length of hair compared to henbit.

HENBIT
(Lamium amplexicaule)
	Cotyledon: round to square, no hair, petiole longer and more vertical than deadnettle, a white point at tip, cotyledon lobes at petiole usually do not touch each other creating a square at the petiole. Leaf: opposite, half the amount and length of hair compared to deadnettle, serrated leaf margin, leaves have petioles as aseedling, but do not have petioles whenflowering begins, round-shaped leaves. Stem: erect to prostrate, square, half the amount and length of hair compared to deadnettle.

MARESTAIL/HORSEWEED
(Conyza canadensis)
		Cotyledon: smooth and green Leaf: often hairy, numerous, linear, crowded together around stem, later alternate. Stem: erect, bristly hairs, strong.

FIELD PENNYCRESS
(Thlaspi arvense)
	Cotyledon: round, hairless. Leaf: no hair, alternate, margins of first leaves are serrated to smooth, later margins are more lobed, stem leaves clasp the stem, when crushed an odor is produced.

SHEPHERD�S-PURSE
(Capsella bursa-pastoris)
		Cotyledon: oval to spatulate. Leaf: similar to cotyledons when young, changing to variable in shape with lobed or toothed and undulating margins, hairy. Special: rosette in the vegetative stage, rosette with erect stem in the reproductive stage. Other: seed pods resemble a purse.

BIENNIAL BROADLEAF WEEDS

WILD CARROT
(Daucus carota)
		Cotyledon: long, linear, smooth. Leaf: compound, lacy, hairy, smells like a carrot. Special: rosette the first year, second year grows a hairy stem, then flowers and dies. Other: sometimes referred to as Queen Anne�s Lace.

POISON HEMLOCK
(Conium maculatum)
	Cotyledon: oblong to elliptical shaped, hairless, veins very prominent. Leaf: finely divided, although each division is wider than wild carrot, no hair, petioles may have purple spots, alternate, when crushed a musty odor is present. Stem: hairless, purple spots on erect stem, basal rosette formed first followed by an erect stem.

PERENNIAL BROADLEAF WEEDS

DANDELION
(Taraxacum officinale)
		Plants can sprout from seed or below ground roots. Cotyledons spatulate to oblong-shaped with no hair. Leaves are variously lobed, and emerge in a rosette. Little or no hair on leaves. A yellow ray of flowers appears on a long fleshy hollow stem.

CURLY DOCK
(Rumex crispus)
	It is a simple perennial, so it can emerge from seed or tap root. As a seedling the cotyledons are linear to oblong and hairless. All nodes have a prominent ocrea. Leaves are linear with a wavy leaf margin, hairless, and alternate. Stems are short early appearing as a rosette and later produce an erect stem. Stem leaves are usually shorter than basal leaves. Leaves and stems often have reddish spots on them.

HEMP DOGBANE
(Apocynum cannabinum)
		Reproducing by seed or long horizontal rootstock. Leaves are oblong to elliptical, opposite and erect. Stems are woody and often red at the base, branching and exude a milky substance when broken. No hair on leaves or stem.

COMMON MILKWEED
(Asclepias syriaca)
		Similar to hemp dogbane, except the stem does not branch and the underside of leaves are hairy. The leaves are larger and more elliptical than hemp dogbane and all plant parts exude a milky substance when broken.

COMMON POKEWEED
(Phytolacca americana)
		Plants can develop from seed or a large poisonous taproot. Leaves appear folded and crinkled when emerging from the soil but soon develop into large simple leaves. Plants have a smooth red stem which can reach a height of 9 feet. Sometimes called �inkberry� because of its distinctive shiny dark-purple berries.

CANADA THISTLE
(Cirsium arvense)
		Can emerge from seeds or creeping roots, beginning as a rosette but quickly elongating a stem which branches only at the top. Leaves clasp the stem, have crinkled margins, and lobes which end in spiny tips. The stem has no spines, but does have hair. Flowers are purple.