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London hedge-mustard, London rocket

hedge-mustard, rocket, tumblemustard

Habit Annuals; glabrous or sparsely pubescent. Plants not scapose; pubescent or glabrous.
Stems

erect, branched proximally and distally, (1–)2–6(–7.5) dm, glabrous or sparsely pubescent at least basally.

often erect, sometimes ascending, rarely subprostrate or decumbent, often branched distally, sometimes unbranched.

Leaves

basal and cauline; petiolate or sessile;

basal rosulate or not, petiolate, blade margins dentate, sinuate, lyrate, runcinate, or pinnately lobed [entire];

cauline similar to basal, (blade smaller distally).

Basal leaves

not rosulate;

petiole (0.5–)1–4.5(–6) cm;

blade oblanceolate or oblong (in outline), (1.5–)3–12(–15) cm × (5–)10–60(–90) mm, margins runcinate to pinnatisect;

lobes (1–)2–6(–8) on each side, oblong or lanceolate, smaller than terminal lobe, margins entire, dentate, or lobed.

Cauline leaves

similar to basal; (distalmost) blade (smaller, to 2 cm wide), margins entire or 1–3-lobed.

Racemes

(several-flowered), often considerably elongated in fruit.

Flowers

sepals erect, oblong, 2–2.5 × 1–1.5 mm;

petals oblong-oblanceolate, 2.5–3.5(–4) × 1–1.5 mm, claw 1–1.5 mm;

filaments 2.5–4 mm;

anthers ovate, 0.5–0.9 mm.

sepals ovate or oblong, (glabrous or pubescent);

petals yellow, obovate, spatulate, oblong, or suborbicular, (longer than sepals), claw differentiated from blade, (subequaling or longer than sepals, apex obtuse or emarginate);

stamens tetradynamous;

filaments not dilated basally;

anthers oblong, (apex obtuse);

nectar glands confluent, subtending bases of stamens, median glands present.

Fruiting pedicels

divaricate or ascending, slender, much narrower than fruit, (5–)7–12(–20) mm.

ascending, divaricate, or erect, slender or stout (sometimes as wide as fruit).

Fruits

(divaricate to ascending, young fruits overtopping flowers), narrowly linear, straight or slightly curved inward, slightly torulose, slender, (2.5–)3–4(–5) cm × 0.9–1.1 mm;

valves glabrous;

ovules 40–90 per ovary;

style 0.2–0.5 mm;

stigma prominently 2-lobed.

usually sessile, rarely shortly stipitate (gynophore to 1 mm), usually linear, rarely lanceolate or subulate, smooth or torulose;

valves each with prominent midvein and 2 conspicuous marginal veins, usually glabrous, rarely pubescent;

replum rounded;

septum complete;

style subclavate [clavate, conical, cylindrical];

stigma capitate (lobes not decurrent).

Seeds

0.8–1 × 0.5–0.6 mm.

plump, not winged, oblong [ovoid];

seed coat (reticulate or papillate), not mucilaginous when wetted;

cotyledons incumbent.

x

= 7.

2n

= 14.

Sisymbrium irio

Sisymbrium

Phenology Flowering Dec–May.
Habitat Rocky slopes, orchards, roadsides, fields, pastures, waste grounds, prairies, disturbed sites
Elevation 0-1700 m (0-5600 ft)
Distribution
from FNA
AZ; CA; CO; CT; FL; ID; MA; MI; NM; NV; OH; PA; TX; UT; WY; Europe; w Asia; c Asia; n Africa [Introduced in North America; introduced also in South America, Australia]
[WildflowerSearch map]
[BONAP county map]
from USDA
North America; Europe; Asia; Africa [Introduced in Central America, South America, Australia]
[BONAP county map]
Discussion

Species 41 (8 in the flora).

All except one of the eight species of Sisymbrium in North America are introduced Eurasian weeds. Sisymbrium linifolium (Nuttall) Nuttall was retained in Sisymbrium by both E. B. Payson (1922) and O. E. Schulz (1924). Greene took that species as the type of his genus Schoenocrambe. R. C. Rollins (1982b, 1993) maintained Schoenocrambe and (1993) recognized Sisymbrium auriculatum as the only native North American species of the genus. Molecular studies (S. I. Warwick et al. 2002, 2005) clearly demonstrated that Schoenocrambe should be united with Sisymbrium, that S. linifolium is most closely related to the Eurasian S. polymorphum (Murray) Roth (as was suggested by both Payson and Schulz), that 40 of the 41 species of Sisymbrium are native to the Old World, and that S. auriculatum is a member of the New World Thelypodieae and is unrelated to Sisymbrium. See also Warwick and I. A. Al-Shehbaz (2003) and Al-Shehbaz (2005).

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

Key
1. Racemes bracteate, flowers fasciculate.
S. polyceratium
1. Racemes ebracteate, flowers not fasciculate
→ 2
2. Fruits subulate-linear, (0.7-)1-1.4(-1.8) cm; fruiting pedicels appressed to rachises.
S. officinale
2. Fruits narrowly linear, 2-10(-13) cm; fruiting pedicels not appressed to rachises
→ 3
3. Fruiting pedicels nearly as wide as fruit
→ 4
3. Fruiting pedicels narrower than fruit
→ 6
4. Distal cauline leaf blades divided into linear or filiform lobes; sepals cucullate; fruiting pedicels (4-)6-10(-13) mm.
S. altissimum
4. Distal cauline leaf blades not divided into linear or filiform lobes; sepals not cucullate; fruiting pedicels 1-6 mm
→ 5
5. Fruiting pedicels 1-2(-3) mm; petals 1.4-2(-2.5) mm; seeds 30-46(-54) per fruit.
S. erysimoides
5. Fruiting pedicels 3-6 mm; petals (6-)7-9(-10) mm; seeds (60-)80-100(-140) per fruit.
S. orientale
6. Perennials; distalmost cauline leaf blades usually filiform to linear, rarely oblanceolate, 1-3.5(-5) mm wide.
S. linifolium
6. Annuals; distalmost cauline leaf blades oblanceolate or oblong (in outline), not filiform or linear, 10-30 mm wide
→ 7
7. Plants usually densely hispid (at least proximally); petals 6-8 mm; young fruits not overtopping flowers.
S. loeselii
7. Plants glabrous or sparsely pubescent; petals 2.5-3.5(-4) mm; young fruits overtopping flowers.
S. irio
Source FNA vol. 7, p. 670. FNA vol. 7, p. 667. Author: Ihsan A. Al-Shehbaz.
Parent taxa Brassicaceae > tribe Sisymbrieae > Sisymbrium Brassicaceae > tribe Sisymbrieae
Sibling taxa
S. altissimum, S. erysimoides, S. linifolium, S. loeselii, S. officinale, S. orientale, S. polyceratium
Subordinate taxa
S. altissimum, S. erysimoides, S. irio, S. linifolium, S. loeselii, S. officinale, S. orientale, S. polyceratium
Synonyms Chamaeplium, Norta, Pachypodium, Schoenocrambe, Velarum
Name authority Linnaeus: Sp. Pl. 2: 659. (1753) Linnaeus: Sp. Pl. 2: 657. (1753)
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