Canola is a global oilseed crop, cultivated extensively for the oil extracted from its seeds. The term “canola” refers to specific varieties of rapeseed, primarily derived from Brassica napus or Brassica rapa, bred to contain low levels of undesirable compounds. The plant progresses through distinct physical changes, starting as a small seedling and culminating in a mature, seed-bearing stalk. This lifecycle involves the emergence of leaves, flowering, and the development of pods that hold the oil-rich seeds.
The Early Vegetative Stage: Leaves and Stems
The canola plant begins its life as a seedling emerging from the soil, displaying two rounded cotyledons (seed leaves). This is followed by the development of the first true leaves. In its early life, the plant remains low to the ground in the rosette stage, which is a tight cluster of leaves that helps the young plant manage resources.
The leaves are hairless and fleshy, often appearing bluish-green or pale. The lower leaves are typically lobed, meaning they have deep, rounded divisions, and are attached to the stem by a stalk. A thin, waxy coating, sometimes called a bloom, covers the leaves and stem, giving the plant a dull, blue-green appearance.
As the plant matures, it transitions into the bolting stage, where the main stem rapidly elongates. This central stem is strong and smooth, continuing to display the waxy coating, and can eventually reach a height of three to five feet. The upper leaves differ from the lower ones, appearing less lobed and partially clasping the stalk.
The Iconic Flowering Stage: Yellow Blossoms
Following the rapid upward growth, the plant enters its most recognizable phase, producing bright yellow blossoms. These flowers are arranged in dense clusters, called an inflorescence or raceme, at the top of the main stem and lateral branches. The flowering process is indeterminate, meaning new flowers open at the top while lower ones begin to form pods.
Each canola flower is small, typically about three-quarters of an inch across, and possesses a symmetrical structure common to the Brassicaceae family. The blossom consists of four vibrant, yellow petals arranged in a cross shape, which is a defining trait of the mustard family. This color attracts pollinators, such as bees, necessary for fertilization and seed production.
When canola fields are in full bloom, the density of the bright yellow flowers creates an immense spectacle of color across the landscape. The flowering period can last for several weeks, during which the plant reaches its maximum height. As fertilization occurs, the petals drop off, marking the transition to a developing seed vessel.
The Mature Reproductive Stage: Pods and Seeds
The final stage is the development and maturation of the seed pods, botanically known as siliques. These pods form where the flowers dropped, beginning with the blossoms lowest on the stem and progressing upward. The siliques are long, narrow, and cylindrical, typically ranging from one to three inches in length.
Internally, each pod is divided by a thin membrane called a septum, with two rows of seeds developing on either side. A single silique can contain 15 to 40 seeds, which start as translucent and turn green as they fill with oil and protein. As the plant approaches maturity, the pods change color from green to a pale yellow or tan, eventually becoming brittle.
The seeds inside the maturing pods undergo a final color change, transitioning from dark green to a hard, spherical seed that is dark brown or black. These mature seeds are small, measuring less than three millimeters in diameter. The plant is considered fully ripe when the seeds are a uniform dark color and have lost most of their moisture.