Descurainia sophia |
Descurainia adenophora |
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fine-leaf tansy-mustard, fixweed, flixweed, flixweed tansymustard, herb sophia, not much flower, tansy mustard |
white tansy mustard |
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Habit | Annuals; eglandular; sparsely to densely pubescent, sometimes glabrous distally, trichomes dendritic. | Biennials; glandular (at least distally); 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, branched distally, 4.5–13 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 1–3 cm; blade pinnate, oblanceolate to obovate or ovate in outline, 2–10 cm, lateral lobes (2–5 pairs), oblanceolate to lanceolate, (4–12 × 1–5 mm),margins entire or serrate to crenate, (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 ascending, greenish to yellowish, oblong, 2–2.9 mm, pubescent, (trichomes dendritic, mixed with glandular papillae); petals oblanceolate, 1.8–2.6 × 0.5–0.7mm; median filaments 1.8–2.4 mm; anthers 0.3–0.5 mm. |
Fruiting pedicels | divaricate to ascending, straight, (5–)8–15(–20) mm. |
divaricate, straight, 13–31 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 erect, linear, slightly torulose, 8–16(–20) × 1–1.3 mm, (abruptly acute at both ends); valves each with distinct midvein, (sparsely pubescent or glabrescent); septum not veined; ovules 48–64 per ovary; style 0.1–0.2 mm, glabrous. |
Seeds | uniseriate, reddish brown, oblong, 0.7–1.3 × 0.3–0.6 mm. |
biseriate, light brown, ellipsoid, 0.9–1.1 × 0.5–0.6 mm. |
2n | = 28. |
= 42. |
Descurainia sophia |
Descurainia adenophora |
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Phenology | Flowering Mar–Jul. | Flowering Jun–Aug. |
Habitat | Roadsides, waste places, disturbed sites, railroad embankments, hillsides, mountain slopes, canyon bottoms, stream banks, fields, lawns, pastures, deserts, sagebrush and pinyon-juniper communities | Open forests, sandy grounds, gravelly flats, disturbed areas |
Elevation | 0-3000 m (0-9800 ft) | 1100-2000 m (3600-6600 ft) |
Distribution |
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]
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AZ; CA; NM; NV; TX; Mexico (Baja California, Chihuahua, Coahuila) |
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.) |
Both L. E. Detling (1939) and R. C. Rollins (1993) treated Descurainia adenophora as a subspecies of D. obtusa, but the differences are so substantial that they should be recognized as distinct species. From the latter, D. adenophora is distinguished by being hexaploid (versus diploid) with densely glandular (versus eglandular) distal parts, longer sepals (2–2.9 versus 1–2 mm) and petals (1.8–2.6 versus 1.2–2 mm), longer fruiting pedicels (13–31 versus 6–15 mm), biseriate (versus uniseriate) seeds, and more ovules (42–64 versus 16–40) per ovary. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 7, p. 528. | FNA vol. 7, p. 520. |
Parent taxa | Brassicaceae > tribe Descurainieae > Descurainia | Brassicaceae > tribe Descurainieae > Descurainia |
Sibling taxa | ||
Synonyms | Sisymbrium sophia, Hesperis sophia, Sisymbrium parviflorum, Sophia parviflora | Sophia adenophora, D. obtusa subsp. adenophora |
Name authority | (Linnaeus) Webb ex Prantl: in H. G. A. Engler and K. Prantl, Nat. Pflanzenfam. 55(III,2): 192. (1891) | (Wooton & Standley) O. E. Schulz: in H. G. A. Engler, Pflanzenr. 86[IV,105]: 321. (1924) |
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