Parts of the Pinto Bean Seed

Dissecting a pinto bean seed is a great way to learn about seed growth. A bean is a simple seed with only a few, easily identifiable parts. This makes it a great learning tool in a classroom or home-learning environment. Encourage students to draw and label the pinto bean seed parts. Then let them plant a few seeds to watch them grow.

Seed Coat

The seed coat is the mottled brown outer layer of the pinto bean seed. This layer is thinner than a sheet of paper and its function is to protect the white, cotyledon layer below.

Micropyle

The micropyle is the small pore located on the seed coat that allows the pinto bean seed to absorb water. When the bean was still in the ovule stage, this is where the pollen tube entered the ovule to fertilize it.

Hilum

The hilum of a seed is the scarred portion of the seed coat. This scar is similar to a human belly button--it marks the place where the pinto bean seed was attached to the main stalk where it developed before it was harvested.

Cotyledon

The cotyledon is the stored food of the pinto bean seed. When you cut the seed in half, the cotyledon fills up the majority of the seed and envelops the embryo.

Embryo

The embryo is located inside the pinto bean. The best way to find the embryo is to cut the pinto bean seed in half lengthwise. The embryo will be attached to the hilum. It looks like a collection of fibers nestled in the cotyledon. The embryo is made up of the radicle, which is the part attached directly to the hilum; the hypocotyl, which is the stem-like section attached to the radicle; and the leafy epicotyl, which extends from the hypocotyl.

Pinto Bean Seeds Really Produce Pinto Beans?

Pinto beans are a variety of field bean, along with navy and kidney beans. Unlike some other bean varieties that remain in the pod for cooking, pinto beans are removed from the pods after harvest and stored dry. Not all pinto beans will germinate and grow into new plants. Small or obviously immature beans shouldn't be planted, nor should beans that have cracks or holes in the seed coat, because it can allow fungi or bacteria to enter the bean while it is growing. When planting pinto beans, choose a site with well-drained, crumbly soil. Amend the soil with a 5-10-10 fertilizer and cultivate it to a depth of 6 inches, and then plant the beans 1 1/2 inches deep. The beans should be planted 2 to 4 inches apart in rows that are spaced 24 to 30 inches apart. Once planted, water the beans to dampen the soil, keeping the soil moist but not saturated until sprouts begin to appear after the beans have germinated.