The cassava plant is a herbaceous perennial, with a small shrubby habit, growing 1 to 1.5 m tall and 90 cm across. The leaves of the cassava are 10-20cm long and 5–12cm broad, palmately 7–9 lobed with 3-7 triangular lobes on each side of the midrib, tapering to a long tip.
The flowers are produced in simple or paniculate cymes growing from the leaf axils. The flower stalks (pedicels) are 8–20cm long, and each flower is in diameter with five creamy white petals with a greenish-yellow center and 19–32 spirally arranged stamens. The fruit is a pear-shaped (pyriform) or ovoid berry 6–12cm long, containing several brown seeds shaped like lima beans. The tubers are mostly smooth and cylindrical, but some cultivars develop lobes (swollen stolons). Some have both secondary and tertiary roots.
Cassava tuberous roots are disk-shaped or elongated. They vary in size from that of a small potato to over 60 cm long and weighing several kilograms. The root is extensively branched, fleshy, and brittle—it breaks easily when pulled out of the ground. Each plant carries up to 75 tubers, which are filled with starch and have thick, bark-like, brown skins.
Magnification of cassava tubers shows that their skin is composed of cells made up of cellulose cell walls thickened slightly by deposits of calcium oxalate crystals called raphides. These are crystal-shaped granules that do not contain starch grains but have needle-like projections that support the walls.
On average cassava roots contain about 24 percent starch by weight, but this can vary from 20-40%. The remainder of the root is made up largely of water (75%) and indigestible cellulose, which serves as a dietary fiber. These two components give raw cassavas a typical bulk density between 0.89 and 1.1 g/cm3.
The dried root powder is about 35% starch by weight, 75% of which is amylopectin and 25% amylose. Cassava roots produce a sweet exudate from their root hairs. Their color varies from pale brown to white depending on the cultivar.
When mature, cassava roots are naturally rich in starch and low in moisture (4-8%), an ideal storage root that can be left in the ground during seasons when it is not economically productive to harvest them. Compared with sweet potato, cassava contains only 1% water, has a much higher tuber yield per unit area, takes less time to grow, and has higher dry matter yields per unit time.
Cassava is propagated using stem cuttings or by adventitious plantlets formed on the phyllodes of the parent plant, both of which form roots upon contact with soil. These methods give rise to high initial variability in early yields so farmers must be sure of the quality and disease resistance of their planting material.
In most tropical countries, young plants are raised from seeds or suckers from mature crops, but this is a risky propagation method because the crop yield cannot be predicted until harvest time. Only about 2% of cassava plants grown from seed produce high yields, whereas 90-100% of the plants grown from suckers produce high yields.