Rapeseed is a crop with yellow flowers, grown in U.S. fields for seed oil. Growers also plant it as a to protect or improve soil between crops. Many varieties bred for food oil are sold as canola.
Appearance
Growth form
It grows for one season or through the winter, depending on planting time and cultivar.
Leaves
The smooth, waxy blue-green leaves partly clasp the stem near the top of the plant.
Flowers
Clusters of four-petaled, light-yellow flowers rise above the leaves.
Fruit
The flowers form long pods filled with small oil-rich seeds.
Brown mustard has green upper leaves that end above the stem and do not clasp it. Rapeseed has waxy blue-green upper leaves that partly clasp the stem.
Why they get mixed up · Both have upright clusters of small yellow, four-petaled flowers.
Field mustard usually has deeper yellow, smaller petals and unopened buds below the open flowers. Rapeseed usually has larger, paler flowers with buds held above the open flowers.
Why they get mixed up · The two crops have similar yellow flowers and clasping upper leaves.
Where it lives
Typical habitats
crop fields
cover-crop fields
Range
In the United States it is cultivated as an oilseed and cover crop, including in the Upper Midwest.
Preferred conditions
It grows best in cool weather and well-drained soil. Seed can germinate when soil is about 41°F (5°C).
Growing it
Care
Farmers grow it for seed oil and as a cover crop. Winter types may tolerate temperatures near 0°F (-18°C) after they are established.
Propagation
It is grown from seed.
Name and classification
About the name
Canola refers to rapeseed bred to meet food-oil standards; canola can come from this species or field mustard (Brassica rapa).
Varieties and forms
Cultivars within this species vary in oil chemistry, winter hardiness, and farm use.