Leaf type: Oblong, lobed, lanceolate, spines on the midrib
Leaf margin: Serrated
Phyllotaxis: Alternate
Colour: Green, the leaf margins may be red, as may the stems
Life cycle: Annual overwintering or biennial, the seeds may germinate in late summer/fall or spring
Leaf (upper side)
Leaf (under side)
Growth habit & biology
Lactuca serriola is an overwintering annual or biennial; the seeds germinate in fall or spring. In locations with consistently moist and nutrient-rich soil, it can grow over one meter tall.
The leaf margins may be dark red in color.
All parts of the plant are edible, Lactuca serriola is the parent species of lettuce (Lactuca sativa) and its varieties, such as butterhead lettuce and romaine lettuce.
Distribution & habitates
Its native range includes Asia, Europe, and North Africa. As an introduced species, it can also be found regionally in Australia, North America, and South America (source).
It colonizes embankments, slopes, roadsides, parks, gardens, ditches, rubble sites, construction sites, and other ruderal habitats. Lactuca serriola is also commonly found in urban areas, for example, in front of houses or in parking lots.
Botany
Lactuca serriola is a member of the daisy family (Asteraceae). Common names include prickly lettuce, milk thistle or compass plant.
The name “compass plant” refers to its characteristic leaf orientation. The leaves are held vertically, with their edges pointing upward, and typically align along a north-south axis. This reduces exposure to the intense late afternoon sun and helps prevent overheating.
