Flora of North America species comparison

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Sonchus oleraceus

Sonchus palustris

annual sow-thistle, common sow-thistle, laiteron, sow thistle

marsh sow-thistle
Habit Annuals or biennials, 10–140(–200) cm. Perennials, 100–150(–350+) cm.
Stem

bases soft to hard, herbaceous, often hollow.

bases hard, sometimes ± woody.
Leaves

blades of mid cauline spatulate or oblong to obovate or lanceolate, 6–35 × 1–15 cm, bases auriculate, auricles deltate to lanceolate, ± straight, acute, margins usually pinnately (often runcinately) lobed, lobes ± deltate to lanceolate, not constricted at bases, terminals usually larger than laterals, entire or dentate.

blades of mid cauline oblong to lanceolate or linear, 15–20+ × 2–3(–8+) cm, bases auriculate, auricles lanceolate to linear, ± straight, acute, margins sometimes pinnately lobed, lobes ± deltate to lanceolate or linear (not constricted at bases), terminals usually larger than laterals, entire or dentate (teeth not notably prickly).
Peduncles

usually glabrous, sometimes stipitate-glandular.

usually setose- to stipitate-glandular.
Involucres

9–13+ mm.

9–13+ mm.
Corollas

ligules ± equaling tubes.

ligules ± equaling tubes.
Phyllaries

usually glabrous, sometimes tomentose and/or stipitate-glandular.

sparsely to densely setose- to stipitate-glandular.
Cypselae

dark brown, mostly oblanceoloid, 2.5–3.5+ mm, ribs 2–4 on each face, faces transversely rugulose or tuberculate across and between ribs;

pappi 5–8 mm.

stramineous, oblong to ellipsoid, 3.5–4 mm, ribs 4–5 on each face, faces transversely rugulose or tuberculate across and between ribs;

pappi 7–9 mm.
2n

= 32, 36.

= 18.

Sonchus oleraceus

Sonchus palustris
Phenology Flowering (Apr–)Jul–Oct (year-round in south). Flowering Jul–Sep.
Habitat Disturbed sites, gardens, roadsides, along streams Disturbed, marshy sites, wet roadside ditches on peaty sand, railroad ditches, wet fields
Elevation 0–2000 m (0–6600 ft) 0–100 m (0–300 ft)
Distribution
from FNA
AK; AL; AR; AZ; CA; CO; CT; DC; DE; FL; GA; IA; ID; IL; IN; KS; KY; LA; MA; MD; ME; MI; MN; MO; MS; MT; ND; NE; NH; NJ; NM; NV; NY; OH; OK; OR; PA; RI; SC; SD; TN; TX; UT; VA; VT; WA; WI; WV; WY; AB; BC; MB; NB; NF; NS; NT; ON; PE; QC; SK; SPM; Greenland; Europe [Introduced in North America; introduced also in Mexico, West Indies, Bahamas, Central America, South America, Africa, Asia, Pacific Islands (New Zealand), Australia]
[WildflowerSearch map]
[BONAP county map]
from FNA
ON; Europe [Introduced in North America]
[BONAP county map]
Discussion

Sonchus palustris was found in Ontario by D. F. Brunton and C. W. Crompton (1993) in the Ottawa area, and by J. K. Morton and J. M. Venn (1995) in the Waterloo region.

The plants in the flora area are subsp. palustris. Subspecies sosnowskyi (Schchian) Boulos, from a single location in the southern Caucasus of eastern Europe, differs primarily in having glabrous stems, peduncles, and heads.

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Source FNA vol. 19, p. 275. FNA vol. 19, p. 275.
Parent taxa Asteraceae > tribe Cichorieae > Sonchus Asteraceae > tribe Cichorieae > Sonchus
Sibling taxa
S. arvensis, S. asper, S. palustris, S. tenerrimus
S. arvensis, S. asper, S. oleraceus, S. tenerrimus
Name authority Linnaeus: Sp. Pl. 2: 794. (1753) Linnaeus: Sp. Pl. 2: 793. (1753)
Web links 
Unless otherwise noted, all data comes from the online version of the Flora of North America, who have made most of their content available via a Creative Commons license (CC BY 4.0).



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