Sonchus arvensis
field sow-thistle, laiteron des champs, perennial sow-thistle
bases hard, sometimes ± woody.
blades of mid cauline oblong to lanceolate, (3–)6–40 × 2–15 cm, bases auriculate, auricles straight or curved, rounded, margins usually pinnately lobed, lobes ± deltate, not constricted at bases, terminals usually larger than laterals, dentate or entire.
sessile- or stipitate-glandular.
10–17+ mm.
ligules ± equaling tubes.
sessile- or stipitate-glandular.
dark brown, oblanceoloid to ellipsoid, 2.5–3.5 mm, ribs 4–5(+) on each face, faces transversely rugulose to tuberculate across and between ribs;
pappi 8–14 mm.
= 36, 54.
Sonchus arvensis
Subspecies 2 (2 in the flora).
Sonchus arvensis is introduced in temperate regions of all continents. Plants of the species prefer relatively cooler, moister climates and are more abundant in the northern part of North America.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Peduncles stipitate-glandular; phyllaries stipitate- glandular | subsp. arvensis |
1. Peduncles sessile-glandular; phyllaries usually sessile-glandular, rarely tomentose | subsp. uliginosus |
- Local floras:
BC, 
CA, 
OR, 
WA - Local Web sites: CalFlora, CalPhotos,
Flora NW, 
Go Botany, 
IL Wildflowers, 
KS Wildflowers, 
MD Biodiversity, 
MI Flora, 
MN Wildflowers, 
MO Plants, 
PNW Herbaria, Turner Photog. 
WildflowerSearch
iNaturalist (observations)
USDA Plants Database- LBJ Wildflower Center
- SEINet
- Plants of the World Online
- Encyclopedia of Life
- Wikipedia
- Google Image Search
