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fine-leaf tansy-mustard, fixweed, flixweed, flixweed tansymustard, herb sophia, not much flower, tansy mustard

blunt tansy mustard

Habit Annuals; eglandular; sparsely to densely pubescent, sometimes glabrous distally, trichomes dendritic. Biennials; glandular or eglandular; finely pubescent, often canescent, trichomes dendritic, sometimes mixed with simple ones.
Stems

erect, unbranched or branched distally, (1–)2–7(–10) dm.

erect, unbranched basally or branched proximally and/or distally, 4–12(–15) dm.

Basal leaves

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 0.5–3.7 cm;

blade pinnate, oblanceolate to obovate or ovate in outline, 1–6 cm, lateral lobes (2–5 pairs), oblanceolate to linear or narrowly lanceolate, (7–25 × 2–10 mm), margins usually entire or serrate, rarely incised, (apex obtuse).

Cauline leaves

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 densely pubescent.

Racemes

considerably elongated in fruit.

considerably elongated in fruit.

Flowers

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 spreading or sometimes ascending, greenish to yellowish, oblong, 1–2 mm, densely pubescent, (trichomes dendritic, sometimes mixed with glandular papillae);

petals oblanceolate, 1–2 × 0.5–0.7 mm (equaling or shorter than sepals);

median filaments 1.4–2 mm;

anthers 0.2–0.3 mm.

Fruiting pedicels

divaricate to ascending, straight, (5–)8–15(–20) mm.

ascending to divaricate, straight, 6–15 mm.

Fruits

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.

divaricate to suberect, linear, slightly torulose, 10–20(–23) × 0.7–1 mm, (acute at both ends);

valves each with distinct midvein, (sparsely to densely pubescent);

septum not veined;

ovules 16–40 per ovary;

style 0.1–0.2 mm, glabrous.

Seeds

uniseriate, reddish brown, oblong, 0.7–1.3 × 0.3–0.6 mm.

uniseriate or biseriate, light brown, oblong, 0.7–1.1 × 0.5–0.6 mm.

2n

= 28.

= 14.

Descurainia sophia

Descurainia obtusa

Phenology Flowering Mar–Jul. Flowering May–Sep(-Oct).
Habitat Roadsides, waste places, disturbed sites, railroad embankments, hillsides, mountain slopes, canyon bottoms, stream banks, fields, lawns, pastures, deserts, sagebrush and pinyon-juniper communities Gravelly grounds, sandy areas, disturbed sites, open forests, plateaus, abandoned mine areas, dry streams and washes
Elevation 0-3000 m (0-9800 ft) 1500-2600 m (4900-8500 ft)
Distribution
from FNA
AK; AR; AZ; CA; CO; CT; DC; DE; GA; IA; ID; IL; IN; KS; KY; LA; MA; ME; MI; MN; MO; MT; NC; ND; NE; NH; NM; NV; NY; OK; OR; PA; RI; SD; TN; TX; UT; VA; VT; WA; WI; WV; WY; AB; BC; MB; NB; NF; NS; NT; ON; PE; QC; SK; YT; Eurasia [Introduced in North America; introduced also in Mexico, Central America, South America, South Africa, Australia]
[WildflowerSearch map]
[BONAP county map]
from FNA
AZ; NM; NV; Mexico (Baja California)
[WildflowerSearch map]
[BONAP county map]
Discussion

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.)

As circumscribed here, Descurainia obtusa is a relatively uniform, diploid species. It probably was involved as a parent of D. adenophora, which is a hexaploid readily distinguished by characters discussed thereunder.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Source FNA vol. 7, p. 528. FNA vol. 7, p. 525.
Parent taxa Brassicaceae > tribe Descurainieae > Descurainia Brassicaceae > tribe Descurainieae > Descurainia
Sibling taxa
D. adenophora, D. brevisiliqua, D. californica, D. incana, D. incisa, D. kenheilii, D. longepedicellata, D. nelsonii, D. obtusa, D. paradisa, D. pinnata, D. sophioides, D. torulosa
D. adenophora, D. brevisiliqua, D. californica, D. incana, D. incisa, D. kenheilii, D. longepedicellata, D. nelsonii, D. paradisa, D. pinnata, D. sophia, D. sophioides, D. torulosa
Synonyms Sisymbrium sophia, Hesperis sophia, Sisymbrium parviflorum, Sophia parviflora Sophia obtusa, Sisymbrium obtusum
Name authority (Linnaeus) Webb ex Prantl: in H. G. A. Engler and K. Prantl, Nat. Pflanzenfam. 55(III,2): 192. (1891) (Greene) O. E. Schulz: in H. G. A. Engler, Pflanzenr. 86[IV,105]: 321. (1924)
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