Seed coat (testa)Protects the seed; it forms from the ovule's outer layers.
HilumMarks where the seed was attached inside the pod.
Cotyledon (seed leaf)Stores food for the seedling; beans have two.
Radicle (embryonic root)Grows into the first root.
Plumule (embryonic shoot)The first shoot and leaves.
EndospermStored food; in corn it is most of the kernel.
Bean (dicot) 3
MicropyleThe pore the pollen tube entered; water gets in there.
HypocotylThe stem below the cotyledons; it joins the radicle.
EpicotylThe stem above the cotyledons, carrying the plumule.
Corn kernel (monocot) 3
Scutellum (cotyledon of corn)Corn's single cotyledon; it passes food to the embryo.
ColeoptileProtects the shoot as it pushes up through soil.
ColeorhizaProtects the root tip as it first emerges.
How this list was compiled: Read 2026-09-26. (1) OpenStax Biology 2e, 32.2 Pollination and Fertilization, https://openstax.org/books/biology-2e/pages/32-2-pollination-and-fertilization : a seed has a seed coat, cotyledons, endosperm and an embryo; dicots two cotyledons; in corn one cotyledon, the scutellum, which absorbs food from the endosperm; plumule, hypocotyl and radicle in both; the epicotyl is the axis above the cotyledons and carries the plumule; the dicot seed coat is the testa and tegmen; the coleorhiza covers the emerging root tip and the coleoptile the shoot tip; the pollen tube enters through the micropyle. (2) Wikipedia, Seed, https://en.wikipedia.org/wiki/Seed : testa, micropyle, epicotyl, plumule, hypocotyl, radicle, coleoptile, coleorhiza. (3) Britannica, Seed, https://www.britannica.com/science/seed-plant-reproductive-part : the hilum as the scar of the seed's attachment, the micropyle persisting as an opening in the seed coat, radicle, plumule or epicotyl, cotyledons, hypocotyl, the scutellum of grasses between embryo and endosperm. Licence: own work
The drawing: Drawn for this site by script, 2026-09-26. Licence: own work
How it works
This parts of a seed diagram shows the two kinds classes compare: a bean, with two cotyledons, and a corn kernel, with one. Start with the 6 main parts, then add the hilum, micropyle and the sheaths of corn.
Read the full guide
The tiny plant inside
Split a soaked bean and the embryo lies along one edge. The radicle becomes the root, the hypocotyl and epicotyl the stem below and above the cotyledons, and the plumule the first leaves.
Bean or corn
A bean stores its food in two cotyledons. Corn keeps most of it in the endosperm, and its single cotyledon, the scutellum, passes that food to the embryo. In corn, sheaths guard the shoot and the root: the coleoptile and the coleorhiza.
Soak a dry bean in water overnight, then rub off the seed coat: it splits into the two cotyledons, and the embryo shows on one.
Questions and answers
What are the 3 parts of a seed?
The seed coat, which protects it; the embryo, the tiny plant inside; and the stored food, held in the cotyledons of a bean or in the endosperm of corn.
What is the hilum on a bean?
The oval scar on the curved edge of the bean, where it was attached inside the pod. The micropyle is the tiny pore just beside it.
Which part of the seed becomes the root?
The radicle. It is the first part to come out when the seed germinates, and it grows down into the soil before the shoot appears.