Composite or aster (Asteraceae family):
Lapsana communis L.
EPPO code:
LAPCO
Other names:
Common nipplewort, dock cress, nippleweed

Species information

Lifecycle:
Annual or winter annual.
Propagation:
Reproduces by seed.
Emergence:
Emerges in the spring and in autumn.
Range and habitat:
Nipplewort is common throughout Europe, but is now becoming more prominent in Ontario, especially in no-till fields. The plant prefers sun to partial shade and moist to dry, gravelly soil. It is commonly found along rivers and roadsides, and in cultivated fields and disturbed areas.
Competitiveness:
Little information exists on the competitiveness of nipplewort, but a Norwegian study has identified it as a contributor to yield losses in carrots. (Fiveland, 1974)

Identification clues

Leaves

Cotyledons:
Round or spoon shaped and covered in soft, white hairs.
Young leaves:
Rosette of thin, green leaves that are elongated with a rounded terminal lobe and 1–4 side lobes.
Mature leaves:
Leaves have one large lobe at the tip and various shaped smaller lobes below. Leaves on the upper stem are more narrow and pointed and lack the basal lobes.

Mature Plant

Stem:
Central stem is erect, often red to green, hollow, much branched, and covered with hairs in the lower part of the plant.
Flowers:
Nipplewort has many branches containing 8–15 yellow flower heads that open from nipple-shaped buds. The inflorescences are dime sized and resemble miniature dandelions with ray florets that have serrated tips. Nipplewort flowers between June and September.

Often mistaken for

I know it's not Sow-thistle species because sow-thistles have soft-spiny to spiny leaf margins, while the leaves of nipplewort have not. Sow-thistle seeds have fluffy white hairs, while nipplewort seeds are free of hair.

I know it's not Prickly lettuce because nipplewort does not have the row of spines that is found on the underside of prickly lettuce leaves. Prickly lettuce seeds have fluffy, white hairs, while nipplewort seeds are free of hair.

A spring-emerged seedling in late June
A spring-emerged seedling in late June.
A fall-emerged plant that is flowering in late June
A fall-emerged plant that is flowering in late June.
The older, lobed basal leaves (left) in contrast to the upper leaves (right)
The older, lobed basal leaves (left) in contrast to the upper leaves (right).
Side view of a flowering plant
Side view of a flowering plant.
Close up of the small, round and yellow flower heads with ray florets that have serrated tips
Close up of the small, round and yellow flower heads with ray florets that have serrated tips.