Sowthistle (3)

Common Sowthistle
Sonchus oleraceus

Family: Sunflower (Asteraceae)
AKA: Annual Sowthistle, Milk Thistle
Photo taken on: August 16, 2011
Location: White Rock, NM
Life Zones: Plains to foothills
Habitat: Disturbed areas, roadsides

Grows to 3ft with a reddish stem that secretes a milky sap when broken. Leaves are blue-green and have spiny teeth on the edges. Flowers are less than 1" across. Compare with Prickly Lettuce which has distinct spines on the underside of the leaf.

Flora of North America reference.

Field Sowthistle
Sonchus arvensis

Family: Sunflower (Asteraceae)
AKA: Perennial Sowthistle
Photo taken on: July 27, 2012
Location: Abiquiu, NM
Life Zones: Plains and foothills
Habitat: Disturbed soil, waste areas

Grows to 3 ½ft tall with hairless stems. Most of the leaves are on the lower part of the stem and have prickly teeth along the edges. Flower heads are up to 1 ½ " across and have hairless bracts. The size of the flower-head differentiates this from the Common Sowthistle as well as the small lobed leaves that clasp the stem. Considered a noxious weed in many states.

Flora of North America reference.

Prickly Sowthistle
Sonchus asper

Family: Sunflower (Asteraceae)
AKA: Spiny Sowthistle
Photo taken on: June 1, 2016
Location: Agua Caliente Spring, Abiquiu, NM
Life Zones: Plains and foothills
Habitat: Disturbed soil, roadsides streamsides

Can grow to 7 feet tall, this one was 2 feet, with a stout, reddish, grooved stem. Leaves have wide rounded lobes at the base that clasp the stem which differentiates it from the Common Sowthistle. Leaves are shiny green and hairless with deeply cut spine tipped teeth. The flower is less than 1 inch across. Leaves are more prickly than the other Sowthistles.

Flora of North America reference.