Lactuca sativa

Species category

Vegetable

Common name

garden lettuce

Diagnostic characters

Planting unit

AcheneAchene:
A dry, hard, one-chambered, one-seeded indehiscent fruit, as in buckwheat (Fagopyrum) or sunflower (Helianthus). The fruit wall is not united with the seed coat.

Shape

ObovateObovate:
Inverted egg shaped with apical end the broadest.

Size

  • Length 4–5 mm
  • Width 1.4–1.6 mm
  • Thickness 0.5–0.6 mm

Color

White to black

Texture

Serrated ribs; the area between the ribs is moderately rough.

Other structures

Several ribs that are longitudinal and finely serrated. ApexApical:
The distal end of the fruit or seed away from the point of attachment or attachment scar.
is pointed.

Identification notes

AchenesAchene:
A dry, hard, one-chambered, one-seeded indehiscent fruit, as in buckwheat (Fagopyrum) or sunflower (Helianthus). The fruit wall is not united with the seed coat.
obovate with a pointed apexApical:
The distal end of the fruit or seed away from the point of attachment or attachment scar.
, flat, and with numerous longitudinal ribs. Ribs rough-textured. Color black to white with various varieties of mottled brown. Scar is basalBasal:
The base of the fruit or seed opposite the apical end.
.

Noxious weed seed categories

Not listed

AOSA examination list

Included

Nomenclature

Family

Asteraceae

Valid name

Lactuca sativa L.

Synonyms

Lactuca scariola L. var. integrata Gren. & Godr.
Lactuca scariola L. var. integrifolia (Bogenh.) G. Beck

 Lactuca sativa.  Black to white achenes with several ribs that are longitudinal, and finely serrated. 
Lactuca sativa. Black to white achenes with several ribs that are longitudinal, and finely serrated. 
 Lactuca sativa.  Black to white achenes with several ribs that are longitudinal and finely serrated. Photo by Ana Margina, USDA-APHIS-PPQ.
Lactuca sativa. Black to white achenes with several ribs that are longitudinal and finely serrated. Photo by Ana Margina, USDA-APHIS-PPQ.