The difference in where corn and peanut plants produce their seeds provides a fascinating study in botanical evolution. Seeds are the reproductive structures of a plant, containing the embryo that grows into the next generation. While both corn and peanuts are staples in agriculture, their methods for seed production are fundamentally distinct, reflecting their separate evolutionary paths as a grass and a legume. Corn develops its seed high above the ground, exposed to the wind, while the peanut buries its seed deep beneath the soil surface.
The Location of Seeds on the Corn Plant
The seeds of the corn plant, commonly called kernels, develop entirely above ground on the main stalk. Corn is a member of the grass family and has separate male and female flower structures (monoecious). The male flower is the tassel, which emerges from the top of the stalk, while the female flowers are clustered lower down, forming the ear.
The ear is a specialized female inflorescence that develops from an axillary bud along the stalk. Each potential kernel on the cob is an ovule, which sends out a single, elongated strand of tissue known as a silk. These silks emerge as a bundle from the tip of the developing ear, covered by the outer husks.
Pollination occurs when wind-carried pollen from the tassel lands on a receptive silk. Each silk must capture a pollen grain to fertilize the ovule it is connected to. If successfully pollinated, the fertilized ovule develops into a kernel. The kernel is botanically a specialized fruit called a caryopsis, meaning the seed coat is fused to the ovary wall, and matures in paired rows around the central cob.
The Unique Development of Peanut Seeds
The peanut plant is known for its reproductive strategy called geocarpy, meaning “earth-fruit.” Although the plant flowers above ground, the fruit and seeds develop exclusively beneath the soil surface. The bright yellow, pea-like flowers are self-pollinating and develop on the aerial parts of the plant.
Once the flower is fertilized, the ovary begins to elongate rapidly into a stalk-like structure known as a peg or gynophore. The peg is positively gravitropic, meaning it grows downward, seeking out the soil.
The peg pushes its way into the earth, and the embryo begins to develop only after the tip successfully penetrates the soil. The tip of the peg then swells to form the pod. The pod, technically a legume, is where the seeds mature, protected by the soil from environmental stresses.
Why Corn and Peanuts Develop Seeds So Differently
The contrasting seed locations stem from their distinct botanical classifications and evolutionary histories. Corn (Zea mays) is a grass characterized by wind-pollination and a single-seeded fruit type. The above-ground arrangement of the tassel and ears facilitates the strategy of releasing lightweight pollen into the air for fertilization.
The peanut (Arachis hypogaea) is a legume, a family that typically produces pods above ground, like peas and beans. The peanut’s geocarpy is an evolutionary adaptation that provides a stable, moist, and nutrient-rich environment for seed maturation. The developing peanut requires calcium, which is absorbed directly from the surrounding soil, necessitating its subterranean development.
The corn kernel is a caryopsis, while the peanut is a true legume, a pod that splits open to reveal multiple separate seeds. These differences in fruit structure, combined with the evolutionary shift to geocarpy in the peanut, explain the disparity in where these staples locate their reproductive structures. Corn invests in height and wind dispersal, while the peanut invests in burying its offspring for protection and direct nutrient access.