Sonchus oleraceus, Common Sowthistle
Scientific Name: Sonchus oleraceus
Common Name: Common Sowthistle
Also Called: Annual Sowthistle, Common Cow Thistle, Common Sow-thistle, Laiteron, Pualele, Sow Thistle and Sow-thistle (Spanish: Chinita, Lechuguilla, Achicoria Dulce, Muela de Caballo)
Family: Asteraceae, Sunflower Family
Synonyms: ( )
Status: Invasive, European native
Duration: Annual or biennial.
Size: 1 to 3 feet or more.
Growth Form: Forb/herb; basal leaves, branching above; stems hollow, mostly hairless (glabrous) ooze milky sap when broken.
Leaves: Green, light or dark green; alternate; basal leaves; upper leaves variable in plant, oblong, obovate, lanceolate, often winged at base, spiny edges deeply lobed.
Flower Color: Yellow; flowers small about ½ to 1 inch, on tips of flowering stalks; strap-shaped (ligulate) flowers only in clusters on open branches; flowers usually bloom mornings to mid-mornings; fruit is an achene with white hairs on one end, seeds are wind dispersed.
Flowering Season: March to September.
Elevation: 500 to 4,500 feet.
Habitat Preferences: Throughout the state, roadsides, yards, gardens, fields, along streams and disturbed areas.
Recorded Range: Widespread throughout North America in every state and most provinces. Common weed in Baja California and northern, central and southern Mexico. In Arizona, Common Sowthistle is found most everywhere in preferred habitat.
U.S. Weed Information: Sonchus oleraceus is listed in: Weeds of the Northeast, Southern Weed Science Society, and Weeds of the West. Plants included here may become weedy or invasive.
Invasive/Noxious Weed Information: No data available.
Wetland Indicator: Sonchus oleraceus is on the USDA 2012 National Wetland Plant List
Threatened/Endangered Information: No data available.
Comments:One of the more predominant plants in Arizona Common or Annual Sowthistle is a major weed species throughout the country. Because it is so prolific, this weed competes with other more "desirable" plant species. It has become naturalized from Europe and is sometimes difficult to distinguish from the similar Spiny Sowthistle, Sonchus asper. One of the main differences, as the name implies, the latter is spinier.
In Southwest Desert Flora also see Prickly Lettuce, Lactuca serriola.
The young basal rosettes are similar in appearance to thistles of the genus Cirsium, thus the common names.