What Is a Scutellum? The Seed Leaf of Grasses and Corn
A scutellum is the single modified seed leaf found in grasses, corn and other monocots. UF IFAS plant propagation notes say monocots reduced the usual pair of cotyledons to one, termed the scutellum, which sits pressed against the starchy endosperm inside the kernel.
The short answer
The scutellum is the one cotyledon of a grass seed. UF IFAS says it works as conductive tissue between the endosperm and the embryo axis. During germination it draws starch from the endosperm and passes it to the young shoot and root. Corn, wheat and rice each have one.
Where is the scutellum in a corn kernel?
Purdue University describes three main kernel parts: the pericarp (outer coat), the endosperm and the embryo. The endosperm fills most of the kernel and is its main energy reserve, mostly starch. The embryo sits on one flat face of the kernel and holds an oil rich cotyledon. That cotyledon is the shield shaped scutellum, backed onto the endosperm.
| Part | Role | Source |
|---|---|---|
| Pericarp | Outer seed coat | Purdue |
| Endosperm | Starch reserve, bulk of the kernel | Purdue |
| Scutellum | Moves food from endosperm to embryo | UF IFAS |
| Embryo axis | Future shoot and root | UF IFAS |
What does the scutellum do?
It’s a go between. UF IFAS calls it conductive tissue linking endosperm and embryo axis. When the seed takes up water, reserves in the endosperm are broken down and the scutellum moves them to the growing shoot and root. Hormones help drive that switch, as cannabis plant hormones explains.
Scutellum vs cotyledon
NC State notes that monocots have one cotyledon and dicots have two. In a bean the two thick cotyledons hold the food. In corn the single scutellum holds little food itself and instead taps the endosperm. Colorado State GardenNotes gives the same split. Compare dicot style seeds in cannabis seed anatomy.
Can I see a scutellum at home?
Yes. Slice a corn kernel lengthwise to find the three parts Purdue names. The pale embryo sits on one face and the starchy endosperm fills the rest. The Kind Seed Co blog covers more seed anatomy too. The leaf tissues that follow after germination are covered in cannabis leaf anatomy, and the start of a plant’s life cycle of a marijuana plant begins right here.
Sources
- Seeds, embryogenesis, Plant Propagation, UF IFAS
- Corn, the great American crop, Purdue University Corny News Network
- Extension Gardener Handbook, chapter 3: botany, NC State Extension
- Botany (CMG GardenNotes 120), Colorado State University Extension
FAQ
Is the scutellum a cotyledon?
Yes. UF IFAS describes the scutellum as the single modified cotyledon of monocots such as grasses.
What does the scutellum do?
UF IFAS says it acts as conductive tissue between the endosperm and the embryo axis, moving stored food to the seedling.
Do beans have a scutellum?
No. NC State notes that dicots such as beans have two cotyledons, while monocots have one.
What is the bulk of a corn kernel?
Purdue says the endosperm occupies most of the kernel and is mostly starch.
Where is the embryo in a corn kernel?
Purdue describes the embryo as one of the three main kernel parts, with an oil rich cotyledon next to the endosperm.
