Descurainia sophia
Descurainia torulosa
fine-leaf tansy-mustard, fixweed, flixweed, flixweed tansymustard, herb sophia, not much flower, tansy mustard
erect, unbranched or branched distally, (1–)2–7(–10) dm.
(several to numerous from base), decumbent, usually unbranched, rarely branched distally, 0.4–1.5 dm.
petiole 0.1–2(–3) cm;
blade 2- or 3-pinnate, ovate or oblong to obovate in outline, to 15 cm, lateral lobes linear or oblong, (to 10 × 2 mm), margins entire.
petiole 0.3–1.4 cm;
blade pinnate, oblanceolate in outline, 0.9–3.5 cm, lateral lobes (3–5 pairs), oblanceolate to oblong, (2–5 × 0.5–1.5 mm), margins entire.
sessile or shortly petiolate;
blade smaller distally, distal lobes often narrower, surfaces often glabrous.
sessile or shortly petiolate;
blade smaller distally, distal lobes often narrower, surfaces moderately pubescent.
considerably elongated in fruit.
considerably elongated in fruit.
sepals erect to ascending, yellowish, oblong, 1.8–2.8 mm, glabrate to sparsely pubescent;
petals narrowly oblanceolate, 2–3 × 0.4–0.6 mm;
median filaments 2–3 mm;
anthers 0.3–0.4 mm.
sepals ascending, yellowish, oblong, 0.9–1.2 mm, pubescent;
petals narrowly oblanceolate, 1.4–2 × 0.4–0.6 mm;
median filaments 1.6–2 mm;
anthers 0.2–0.3 mm.
divaricate to ascending, straight, (5–)8–15(–20) mm.
erect to erect-ascending, straight, 1.5–3 mm.
divaricate-ascending to erect, narrowly linear, torulose, (12–)15–27(–30) × 0.5–0.8(–1) mm, (straight or curved upward);
valves each with distinct midvein;
septum with a broad central longitudinal band appearing as 2 or 3 veins;
ovules 20–48 per ovary;
style obsolete, 0.05–0.2 mm, glabrous.
erect, (subappressed to rachis basally), narrowly linear, strongly torulose, 6–15 × 0.6–0.8 mm, (curved outward distally);
valves each with obscure midvein, (pubescent);
septum not veined;
ovules 10–18 per ovary;
style obsolete, 0.1–0.3 mm, sparsely pubescent.
uniseriate, reddish brown, oblong, 0.7–1.3 × 0.3–0.6 mm.
uniseriate, reddish brown, oblong, 1–1.3 × 0.5–0.6 mm.
= 28.
Descurainia sophia
Descurainia torulosa
Deviant chromosome counts (e.g., 2n = 12, 14, 20, 38; see R. C. Rollins 1993, N. H. Holmgren 2005b, S. I. Warwick and I. A. Al-Shehbaz 2006) are most certainly erroneous, and the species appears to be exclusively tetraploid based on x = 7.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Of conservation concern.
Descurainia torulosa is known from Fremont, Park, Sweetwater, and Teton counties. It was studied by J. S. Bricker et al. (2000), who concluded that its status and relationship to D. incana remain unresolved as they were unable to find a set of morphological characters that consistently separated the two taxa. We believe that D. torulosa should be maintained, and that it is easily distinguished from D. incana by having fruits strongly torulose (versus weakly or not torulose), pubescent (versus glabrous), and distinctly curved (versus straight) distally, sparsely pubescent (versus glabrous) styles, fruit valves each with obscure (versus distinct) midvein, and stems decumbent, unbranched, and often several (versus stems erect, branched, and simple) from the base.
Descurainia torulosa is in the Center for Plant Conservation’s National Database of Endangered Plants.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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