The green links below add additional plants to the comparison table. Blue links lead to other Web sites.
enable glossary links

bird's rape, bird-rape, canola, common mustard, field-mustard, rape, rapeseed, turnip, turnip-rape, wild-rape, wild-turnip

cabbage, cole, mustard, turnip

Habit Annuals or biennials; (roots fleshy or slender); (green to slightly glaucous), glabrous or sparsely hairy. Annuals, biennials, or, rarely, perennials; not scapose; glabrous, glabrescent, or pubescent.
Stems

unbranched or branched distally, 3–10 dm.

erect, unbranched or branched distally.

Leaves

basal and cauline; petiolate or sessile;

basal (persistent in B. tournefortii), rosulate or not, petiolate, blade margins entire, dentate, or lyrate-pinnatifid;

cauline petiolate or sessile, blade (base sometimes auriculate or amplexicaul), margins entire, dentate, lobed, or sinuate-serrate.

Basal leaves

petiole (winged), (1–)2–10(–17) cm;

blade ± lyrate-pinnatifid to pinnate to pinnatisect, (5–)10–40(–60) cm × 30–100(–200) mm, (margins sinuate-dentate, sometimes ciliate), lobes 2–4(–6) each side, (terminal lobe oblong-obovate, obtuse, large, blade surfaces usually setose).

Cauline leaves

(middle and distal) sessile;

base auriculate to amplexicaul, (margins subentire).

Racemes

not paniculately branched, (with open flowers overtopping or equal to buds).

(corymbose), considerably elongated in fruit.

Flowers

sepals (3–)4–6.5(–8) × 1.5–2 mm;

petals deep yellow to yellow, obovate, 6–11(–13) × (2.5–)3–6(–7) mm, claw 3–7 mm, apex rounded;

filaments 4–6(–7) mm;

anthers 1.5–2 mm.

sepals usually erect or ascending, rarely spreading, oblong [ovate], lateral pair usually saccate basally;

petals yellow to orange-yellow [rarely white], obovate, ovate, elliptic, or oblanceolate, claw often differentiated from blade, (sometimes attenuate basally, apex rounded or emarginate);

stamens tetradynamous;

filaments slender;

anthers oblong or ovate, (apex obtuse);

nectar glands confluent or not, median glands present.

Fruiting pedicels

ascending to spreading, (5–)10–25(–30) mm.

erect, spreading, ascending or divaricately-ascending, often slender.

Fruits

ascending to somewhat spreading, torulose, terete, (2–)3–8(–11) cm × 2–4(–5) mm;

valvular segment with 8–15 seeds per locule, (1.3–)2–5(–7.5) cm, terminal segment seedless, 8–22 mm.

siliques, dehiscent, sessile or stipitate, segments 2, linear, torulose or smooth, terete, 4-angled, or latiseptate; (terminal segment seedless or 1–3-seeded, usually filiform or conic, rarely cylindrical);

valves each prominently 1-veined, glabrous;

replum rounded;

septum complete;

ovules [4–]10–50 per ovary;

stigma entire or 2-lobed.

Seeds

black, brown, or reddish, 1.1–2 mm diam.;

seed coat very finely reticulate-lightly alveolate, not mucilaginous when wetted.

uniseriate, plump, not winged, globose;

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

cotyledons conduplicate.

x

= 7, 8, 9, 10, 11.

2n

= 20.

Brassica rapa

Brassica

Phenology Flowering Apr–Sep.
Habitat Roadsides, disturbed areas and waste places, cultivated fields, grain fields, orchards, gardens
Elevation 0-1500 m [0-4900 ft]
Distribution
from FNA
AK; AL; AR; AZ; CA; CO; CT; DC; DE; FL; GA; IA; ID; IL; IN; KS; KY; LA; MA; MD; ME; MI; MN; MO; MS; MT; NC; ND; NE; NH; NJ; NM; NV; NY; OH; OK; OR; PA; RI; SC; SD; TN; TX; UT; VA; VT; WA; WI; WV; WY; AB; BC; MB; NB; NL; NS; NT; ON; PE; QC; SK; YT; Europe; Asia; Africa [Introduced in North America; introduced also in Mexico, West Indies, Central America, South America, Atlantic Islands, Australia]
[WildflowerSearch map]
[BONAP county map]
from USDA
sw Europe; sw Asia; e Africa; nw Africa [Introduced in North America; introduced also in Mexico, West Indies, Central America, South America, Atlantic Islands, Pacific Islands (New Zealand), Australia]
[BONAP county map]
Discussion

Brassica rapa is widely cultivated as an oil crop and vegetable, and cultivars, especially in Asia, have been recognized as species, subspecies, and varieties. The most important crops include: rapeseed or canola, turnip (subsp. rapa), Chinese mustard or pakchoi [subsp. chinensis (Linnaeus) Hanelt], and Chinese cabbage or petsai [subsp. pekinensis (Loureiro) Hanelt]. The species is also a widespread naturalized weed [subsp. sylvestris (Linnaeus) Janchen] throughout temperate North America and elsewhere. It is self-incompatible. Hybridization in the field in Europe has been described between B. napus and B. rapa (R. B. Jørgensen and B. Andersen 1994).

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

Species 35 (8 in the flora).

Crops of Brassica are the most important economic plants of the family. Probably, the earliest known utilization of mustards dates from Sanskrit records in India to 3000 b.c., but there is archaeological evidence suggesting that cultivation of cabbage in coastal northern Europe was occurring nearly 8000 years ago. Brassica crops include oilseeds, food crops (e.g., B. juncea, Asian vegetables; B. oleracea, cole crops; B. rapa, Chinese cabbages), fodder for animals, and condiments (B. juncea or B. nigra). The latter two species have also been used for medicinal purposes (I. A. Al-Shehbaz 1985). In addition to being noxious weeds, some species of Brassica are harmful or poisonous to humans and livestock (Al-Shehbaz).

Historically, native peoples of North America have used a number of “wild” Brassica species for both food and medicinal purposes (T. Arnason et al. 1981; H. A. Jacobson et al. 1988): Brassica species—young shoots cooked as greens by Iroquois and Malecite Indian tribes; B. nigra—seeds ground and used as snuff to cure head colds by the Meskwaki, and leaves used to relieve toothaches and headaches by the Mohegans; B. napus—bark used to treat colds, cough, grippe, and smallpox by the Micmac, and used for chilblains by the Rappahannock; B. oleracea—used for headaches by the Rappahannock; and B. rapa—used as medicine by the Bois Fort Chippewa.

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

Key
1. Cauline leaves sessile, blade bases auriculate and/or amplexicaul
→ 2
1. Cauline leaves petiolate or sessile, blade bases tapered, not auriculate or amplexicaul
→ 4
2. Biennials or perennials; petals (15-)18-25(-30) mm; terminal segments of fruits (3-)4-11 mm.
B. oleracea
2. Annuals or biennials; petals 6-16 mm; terminal segments of fruits (5-)8-22 mm
→ 3
3. Flowers usually not overtopping buds, rarely at same level, when open; petals pale yellow, 10-16 mm; terminal segments of fruits (5-)9-16 mm.
B. napus
3. Flowers overtopping or equaling buds when open; petals deep yellow, 6-11(-13) mm; terminal segments of fruits 8-22 mm.
B. rapa
4. Fruits and pedicels erect, ± appressed to rachises; fruits 10-25(-27) mm, not torulose; fruiting pedicels (2-)3-5(-6) mm.
B. nigra
4. Fruits and pedicels spreading to ascending, not appressed to rachises; fruits often 2 cm+, torulose; fruiting pedicels (6-)8-20 mm
→ 5
5. Fruits stipitate, gynophores 1.5-4(-5) mm, terminal segments 0.5-2.5(-3) mm; basal leaf blade margins entire or dentate.
B. elongata
5. Fruits sessile or stipitate, gynophores to 1 mm, terminal segments (4-)5-20 mm; basal leaf blade margins lyrate to pinnatisect, or pinnatifid to pinnately lobed
→ 6
6. Basal leaves persistent, blades with 4-10 lobes each side, surfaces hirsute; petals 4-7 × 1.5-2(-2.5) mm.
B. tournefortii
6. Basal leaves deciduous, blades with 1-3 (or 4) lobes each side, surfaces glabrous or nearly so; petals (7-)9-13 × 3-7.5 mm
→ 7
7. Fruits stipitate (gynophore 1-1.5 mm), 1.5-3 cm × 1.5-2 mm, terminal segment 3-6 mm.
B. fruticulosa
7. Fruits sessile, (2-)3-5(-6) cm × 2-5 mm, terminal segment (4-)5-10 (-15) mm.
B. juncea
Source FNA vol. 7, p. 423. FNA vol. 7, p. 419.
Parent taxa Brassicaceae > tribe Brassiceae > Brassica Brassicaceae > tribe Brassiceae
Sibling taxa
B. elongata, B. fruticulosa, B. juncea, B. napus, B. nigra, B. oleracea, B. tournefortii
Subordinate taxa
B. elongata, B. fruticulosa, B. juncea, B. napus, B. nigra, B. oleracea, B. rapa, B. tournefortii
Synonyms B. campestris, B. campestris var. oleifera, B. chinensis, B. pekinensis, B. rapa subsp. chinensis, B. rapa subsp. pekinensis, Sinapis pekinensis
Name authority Linnaeus: Sp. Pl. 2: 666. (1753) Linnaeus: Sp. Pl. 2: 666. (1753): Gen. Pl. ed. 5, 299. (1754)
Web links