Sonchus asper
Sonchus tenerrimus
laiteron rude, prickly sow-thistle, sharp-fringe sow thistle, spiny sow-thistle, spiny-leaf sow-thistle
slender sow-thistle
bases soft, herbaceous, hollow.
bases soft to hard, herbaceous, often hollow.
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.
blades of mid cauline oblong, 3–20 × 2–6 cm, bases auriculate, auricles ovate to lanceolate or linear, ± straight, obtuse to acute, margins usually pinnately lobed, lobes ± rhombic to lanceolate (constricted at bases) or ± linear, terminals ± equaling laterals, entire or dentate.
usually stipitate-glandular, sometimes glabrous.
usually setose- to stipitate-glandular, often tomentose as well, sometimes glabrous.
9–13+ mm.
10–12+ mm.
ligules mostly shorter than tubes.
ligules longer than tubes.
usually stipitate-glandular.
usually setose- to stipitate-glandular, sometimes tomentose as well.
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.
reddish brown, oblanceoloid, 2.5–3.5 mm, ribs 1–3 on each face, faces transversely rugulose or tuberculate across and between ribs;
pappi 5–8 mm.
, biennials, or perennials, 10–80 cm.
= 18.
= 14.
Sonchus asper
Sonchus tenerrimus
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.)
Sonchus tenerrimus was known historically on ballast from Alabama, Pennsylvania (Philadelphia), New Jersey, New York, and, possibly, Quebec.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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