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Summer Annual Weeds

On this page
  • Barnyardgrass
  • Cockleburs
  • Common lambsquarters
  • Common purslane
  • Crabgrasses
  • Foxtails
  • Hairy fleabane
  • Horseweed
  • Ladysthumb
  • Morningglories
  • Mustards
  • Pigweeds
  • Russian thistle
  • Sprangletops
  • Sweetclover
  • Common knotweed

Use the photos below to identify weeds in the field. Names link to more information on identification and biology.

Click on photos to enlarge
Seedling of barnyardgrass, 
				Echinochloa crus-galli.
(Echinochloa crus-galli): Grass family; summer annual; first leaf dull gray green; stem flattened, purplish; no ligule.
Seedling of common cocklebur.
Common cocklebur
(Xanthium strumarium): Sunflower family; summer annual; seed leaves bright green, shiny on upper surface, pointed, and about 6 times longer than wide; true leaves on seedlings notched on margins and taper to leaf tip; bur may remain attached to base of seedling.
Seedling of common lambsquarters.
Common lambsquarters
(Chenopodium album): Goosefoot family; summer annual; seed leaves are narrow, with nearly parallel sides; seed leaves and early true leaves dull blue-green above and often purple below.
Seedling of common 
					purslane, Portulaca oleracea.
Common purslane
(Portulaca oleracea): Purslane family; summer annual; seed leaves oblong, somewhat club shaped, succulent, maroon on lower surface, and green or maroon on upper surface; young leaves smooth, succulent, oblong, green on upper surface, maroonish underneath, and broadest around leaf tip, with short petioles.
Seedling of smooth crabgrass.
(Digitaria spp.): Grass family; summer annual; stems branch at base, are flattened in cross-section, and grow upright or prostrate; leaves are flat, rolled in the bud and have a prominent midvein; sheaths are open and flattened.
Seedling of yellow foxtail.
(Setaria spp.): Grass family; summer annual; first leaves are usually parallel to the ground; grow in loose clumps or singly; stems are erect or bent at the base, but overall ascend upward; mature leaves are long and most have a spiral twist.
Seedling of hairy fleabane.
Hairy fleabane
(Conyza bonariensis): Sunflower family; summer annual; seed leaves gray green; first leaves narrow and covered with short, soft hairs; often wrinkled or distorted.
Seedling of horseweed.
(Conyza canadensis): Sunflower family; summer annual; seed leaves dull green, oval with fine hairs, and with short stalks that sometimes may be tinged brown-purple; first true leaves covered with hairs on upper surface and margins; undersides of early leaves smooth.
Seedling of ladysthumb.
(Polygonum persicaria): Buckwheat family; summer annual; cotyledons are wide, dull green, oblong, with short hairs on the edges near the base, and have short stalks that are fused at the base.
Seedling of 
				annual morningglory, Ipomoea sp.
(Ipomoea spp.): Morningglory family; summer annual; seed leaves deeply notched; heart-shaped first true leaves with deep lobes at base; stem below seed leaves maroon at base and green toward leaf tip.
Mustard seedling.
(Brassica spp.): Mustard family; winter or summer annual or biennial; cotyledons are kidney shaped, broader than long, hairless, and have a deep notch at tip; stalks are longer than the cotyledon blade; first true leaves are bright green on upper surface and paler below.
Redroot pigweed seedlings.
(Amaranthus spp.): Pigweed family; summer annual; seed leaves long and narrow with red undersides; first true leaves have notched tips and much broader than seed leaves.
Seedling of Russian thistle.
Russian thistle
(Salsola tragus): Goosefoot family; summer annual; cotyledons and first true leaves long and thin; first leaves are fleshy, soft, and weakly spine-tipped; stems slender and flexible, often with reddish purple striations along their length.
Seedling of bearded sprangletop.
(Leptochloa fascicularis): Grass family; summer annual; leaves on seedlings are light green usually with a white midrib.
Seedling of white sweetclover.
(Melilotus sp.): Pea family; biennial, sometimes annual or short-lived perennial; seed leaves oblong, smooth; first true leaf oval, narrow at base and squared at tip with a minute nipplelike point; subsequent leaves compound with three leaflets, each resembling the first true leaf.
Seedling of common knotweed.
Common knotweed
(Polygonum arenastrum): Seed leaves are long, very narrow, rounded at the tip and light green with a white cast. The true leaves are much broader, emerging from an encircling, membranous sheath at the leaf base.

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