Coleseed
Brassica napus arvensis
Family: Brassicaceae or Cruciferae
What it is like
Brassica napus arvensis is a ANNUAL/BIENNIAL growing to 1.2 m (4ft). See above for USDA hardiness. It is hardy to UK zone 7 and is not frost tender. It is in flower from May to August. The species is hermaphrodite (has both male and female organs) and is pollinated by Bees. The plant is self-fertile. Suitable for: light (sandy), medium (loamy) and heavy (clay) soils, prefers well-drained soil and can grow in heavy clay soil. Suitable pH: mildly acid, neutral and basic (mildly alkaline) soils and can grow in very acid and very alkaline soils. It can grow in semi-shade (light woodland) or no shade. It prefers moist soil.
Height (m): 1.2
Where it is found
Banks of streams, ditches and arable fields in Britain.
Europe - Mediterranean. Naturalized in Britain.
Conservation Status:
Countries/locations it is found in
How it is used
Food
Rating: 3
Leaves - raw or cooked. Added to salads or used as a potherb. Immature flowering stems - cooked in much the same way as broccoli. An edible oil is obtained from the seed, it is used mainly for cooking purposes, but also for salads. Some caution is advised, see the notes above on toxicity. The sprouted seed is often used as the mustard part of mustard and cress. Eaten in salads. The seed is used as a mustard flavouring.
Oil: Oil
Seed: includes nuts, cereals, peas and beans.
Condiment: the various plants that are used as flavourings, either as herbs, spices or condiments.
Medicine
Rating: 2
The root is emollient and diuretic. The juice of the roots is used in the treatment of chronic coughs and bronchial catarrh. The seed, powdered, with salt is said to be a folk remedy for cancer. Rape oil is used in massage and oil baths, it is believed to strengthen the skin and keep it cool and healthy. With camphor it is applied as a remedy for rheumatism and stiff joints.
Diuretic: Acts on the kidneys, promoting the flow of urine.
Emollient: Softens the skin, causing warmth and moisture.
Other
Rating:
The seed contains up to 45% of an edible semi-drying oil, it is used as a luminant, lubricant, in soap making etc. A good green manure, the deep taproot improves drainage and loosens heavy soils.
Fodder: Food given to the animals (including plants cut and carried to them) rather than forage for themselves.
Green manure: Fast-growing plants that can be used to increase the fertility of the soil.
Oil: Vegetable oils have many uses, as lubricants, lighting, soap and paint making, waterproofing etc. This does not include the edible oils unless they are also mentioned as having other uses.
How it is grown
Succeeds in full sun in a well-drained fertile preferably alkaline soil. Succeeds in any reasonable soil. Prefers a heavy soil and cool moist conditions. Sunny days and cool nights are favourable for plant growth whilst dry weather at harvest time is essential. Coleseed is reported to tolerate an annual precipitation of 30 to 280cm, an annual average temperature range of 5 to 27°C and a pH in the range of 4.2 to 8.2. Very young plants are susceptible to cold damage, -4°C either killing or injuring seedlings, whereas -2°C has no affect when the plants are more than one month old. Coleseed is the form of this species most often found either escaped or naturalized in Britain. It has a non-tuberous root and has been cultivated as a fodder crop, oil-seed crop and green manure. Coleseed is 70% self-pollinating and 30% cross-pollinated. Even if wind and insects are absent, seed are still produced. Yield increases with honeybees. The growth of this plant is inhibited by field mustard and hedge mustard growing nearby. This species is closely related to B. rapa.
Propagating it: Seed - sow in situ in early spring to mid-August for a green manure crop.
Best place to grow: Cultivated Beds;
Habit: Annual/Biennial
Hardiness: 6-9
Growth:
Soil: Light (sandy), medium, heavy (clay)
Shade: Semi-shade, no shade
Moisture: Moist
Things to keep in mind
The oil contained in the seed of some varieties of this species can be rich in erucic acid which is toxic. However, modern cultivars have been selected which are almost free of erucic acid.