Flora of North America species comparison

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Sonchus asper

laiteron rude, prickly sow-thistle, sharp-fringe sow thistle, spiny sow-thistle, spiny-leaf sow-thistle
Habit Annuals or biennials, 10–120(–200+) cm.
Stem

bases soft, herbaceous, hollow.
Leaves

blades of mid cauline spatulate or oblong to obovate or lanceolate, 6–30 × 1–15 cm, bases auriculate, auricles often recurved or curled, rounded, margins often pinnately lobed, lobes ± deltate (not constricted at bases), terminals usually larger than laterals, usually prickly-dentate.
Peduncles

usually stipitate-glandular, sometimes glabrous.
Involucres

9–13+ mm.
Corollas

ligules mostly shorter than tubes.
Phyllaries

usually stipitate-glandular.
Cypselae

stramineous to reddish brown, mostly ellipsoid, strongly compressed, ± winged, 2–3 mm, ribs 3(–5) on each face, faces smooth across and between ribs;

pappi 6–9 mm.
2n

= 18.

Sonchus asper
Phenology Flowering (Mar–)Jul–Nov (year-round in south).
Habitat Disturbed sites, roadsides, along streams
Elevation 0–2500+ m [0–8200+ 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; NL; NS; ON; PE; QC; SK; YT; SPM; Europe; w Asia; n Africa [Introduced in North America; introduced also in Mexico, Central America, West Indies, Bermuda, South America, e Asia, s Africa, Pacific Islands (New Zealand), Australia]
[WildflowerSearch map]
[BONAP county map]
Discussion

L. Boulos (1973) distinguished subsp. asper (annuals with leaves mostly cauline, cypselae margins little or not at all curved and/or ciliate, and one pair of chromosomes with small satellites) from subsp. glaucescens (biennials with leaves mostly in rosettes, leaves mostly stiffer and more prickly than in subsp. asper, cypselae with curved, ciliate margins, and two pairs of chromosomes with large satellites) and noted that the two subspecies are morphologically rather difficult to distinguish if the specimen in hand lacks the rootstock or stem base.

According to H. N. Barber (1941), crosses between Sonchus asper and S. oleraceus resulted in sterile hybrids.

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Source FNA vol. 19, p. 275.
Parent taxa Asteraceae > tribe Cichorieae > Sonchus
Sibling taxa
S. arvensis, S. oleraceus, S. palustris, S. tenerrimus
Synonyms S. oleraceus var. asper
Name authority (Linnaeus) Hill: Herb. Brit. 1: 47. (1769)
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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