WSU Extension

Hortsense

Weeds
 
Annual bluegrass 
Barnyardgrass 
Bentgrass, creeping 
Bermudagrass 
Bittercress (Shotweed, Hairy bittercress) 
Bittersweet nightshade (European bittersweet) 
Black medic 
Blackberry (Himalayan, Evergreen, Pacific) 
Blue mustard (Purple mustard, Tenella mustard) 
Brackenfern, western 
Buffalobur 
Bull thistle 
Buttercup, creeping 
Canada thistle 
Catchweed bedstraw (Cleavers) 
Catsear, common (False dandelion) 
Chickweed, common and mouseear 
Clover 
Comfrey 
Crabgrass 
Dandelion 
Dock (Curly, Broadleaf) 
Dodder 
Downy brome (Cheatgrass, Downy chess) 
Dwarf mistletoes 
English daisy (Lawn daisy) 
English ivy 
Field bindweed (Wild morningglory) 
Field pennycress (Fanweed) 
Flixweed 
Foxtail (Green, Yellow, Bristly) 
Garden loosestrife 
Giant hogweed 
Goldenrods 
Groundsel, common 
Hawkweeds 
Hedge bindweed 
Henbit 
Herb Robert (Robert geranium, stinky Bob) 
Horsetails (Scouringrush) 
Horseweed (Marestail) 
Knapweeds 
Knotweeds (Bohemian, Giant, Japanese, Himalayan) 
Kochia 
Lambsquarters, common 
Liverworts 
Mallow, common (Cheeseweed, Buttonweed) 
Nightshades 
Oxalis (Creeping woodsorrel) 
Parrotfeather and Eurasian watermilfoil 
Pineappleweed 
Plantain (Broadleaf, Buckhorn) 
Poison hemlock 
Poison ivy and Poison oak 
Prickly lettuce (China lettuce) 
Prostrate knotweed 
Puncturevine (Tackweed, Goathead) 
Purple deadnettle (Red deadnettle) 
Purple loosestrife (Purple lythrum) 
Purslane, common 
Quackgrass 
Red sorrel (Sheep sorrel) 
Redroot pigweed (Rough pigweed) 
Redstem filaree (Stork's bill, Crane's bill) 
Reed canarygrass 
Russian thistle (Tumbleweed) 
Ryegrass, annual (Italian ryegrass) 
Salsify (Goatsbeard) 
Scotch broom 
Shepherd's-purse 
Smartweeds 
Sowthistle, annual and perennial 
Speedwells 
Spurges (Prostrate spurges) 
St. Johnswort, common (Goatweed, Klamathweed) 
Stinging nettle 
Tansy ragwort 
Tumblemustard (Jim Hill mustard) 
Velvetgrass (Common velvetgrass) 
Velvetleaf 
Water primrose 
Waterhemlock, western 
Yellow nutsedge 



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Caption: Prickly lettuce leaves
Photo by: R. Parker
  
Weeds : Prickly lettuce (China lettuce) : Lactuca serriola
(revision date: 4/5/2016)

Family: Asteraceae (Compositae)
Cycle: Annual/Biennial
Plant Type: Broadleaf

Biology
Prickly lettuce grows from one to five feet tall from a large taproot. The sap is milky. Seedling plants have slightly lobed leaves with spines on the back of the light-colored midvein. On more mature plants, leaves are alternate with spines or prickles both on the leaf margins and beneath the midvein. Upper leaves are frequently deeply lobed, while lower leaves may be without lobes. Leaves partially surround the stem at the base of the leaf (clasping). Branching typically occurs only in the flowering portion of the plant, where numerous 1/8- to 1/3-inch-wide, pale yellow flower heads are produced on stalks from leaf axils. Petals often turn blue as they dry. Flowers are followed by dandelion-like fuzzballs of plumed seeds. SPECIAL INFORMATION: Young growth is reported to be somewhat toxic to cattle, horses, and sheep.
Habitat
Prickly lettuce is common in waste places and disturbed sites such as roadsides, yards, gardens, and irrigated crops, often on light or dry soils. It is not usually a problem in maintained lawn and turfgrass.

Management Options

Non-Chemical Management
  • Maintaining a healthy planting or turf area to provide competition will prevent weed establishment.
  • Cultivation (rototilling or hoeing) will effectively eliminate plants.
  • Hand-pull to eliminate weeds.
  • Mowing to prevent seed production is a very effective means of management. In lawns, mowing regularly at the proper height for the grass species may help minimize weed growth and invasion.
  • Careful digging is useful to manage weed populations. However, digging can carry undesirable weed seed to the surface and foster further germination.
Select non-chemical management options as your first choice!

Chemical Management

Apply according to label directions. Glyphosate and glufosinate products should be applied as spot treatments only! NOTE: Some ingredients listed here are only available in combination. Read the label carefully on combination products to make sure the product is suitable for your specific situation.

Landscape areas
  • glyphosate
  • glufosinate
Turf areas
  • products containing 2,4-D
  • products containing MCPA
  • triclopyr
Bare ground areas
  • glyphosate
Images

+ Show larger images

 
Caption: Prickly lettuce leaves
Photo by: R. Parker
Caption: Prickly lettuce flower
Photo by: D.G. Swan
Caption: Milky fluid exuding from prickly lettuce cut stem
Photo by: D.G. Swan
Caption: Prickly lettuce flower
Photo by: T.W. Miller
Caption: Prickly lettuce prickles
Photo by: T.W. Miller
Caption: Prickly lettuce flower stalks
Photo by: R. Parker
Caption: Prickly lettuce
Photo by: J.A. Kropf