See what’s inside a bean, how it grows, and the start of a beanstalk.
Beans are one of the most versatile, nutritious, and commonly consumed foods across cultures worldwide. Though they seem simple on the outside beans actually have a complex internal structure that allows them to grow and reproduce. In this article, we’ll explore what’s inside a bean how the different parts contribute to its function as a seed, and the nutritional benefits these components impart.
The Outer Covering: The Seed Coat
The outermost layer of a bean is called the seed coat or testa. This protective covering is formed while the bean develops inside the ovary of the plant. It encases the entire bean in a waterproof, external shield.
The seed coat plays several important roles
- Protects the inner components from damage and decay
- Blocks water absorption until optimal germination conditions arise
- Provides a barrier to oxygen, regulating respiration before germination
- Contains indigestible fibers and phytochemicals that benefit human health
This tough outer shell makes up 5-10% of the bean’s total weight. Though we don’t consume the seed coat, it influences the bean’s shelf life, viability, and nutritional value.
Nourishment for the Embryo: Cotyledons
If you split a bean in half, you’ll discover two chunky halves encased in the seed coat. These are called cotyledons, which serve as the food supply for the plant embryo. The number of cotyledons can vary between plant species. Beans, peas, and lentils have two, which is why they are called dicotyledonous seeds.
The cotyledons consist of parenchyma tissue filled with starch, protein, and oils. As the seed germinates, enzymes break down these stored food resources into nutrients the embryo can consume. The cotyledons sacrifice their stored energy to fuel the embryo’s growth before the seedling can synthesize its own food via photosynthesis.
In beans we eat, the cotyledons provide the majority of the calories, protein, vitamins, minerals, and bioactive compounds that make beans so healthy Though low in fat, the small amount present supplies essential fatty acids
The Genesis of the Plant: The Embryo
At the center of the bean, connecting the two cotyledons, is the embryo. This miniature plant is alive but dormant within the seed, just waiting for the right conditions to sprout.
When water is absorbed, the embryo grows, breaking out of the seed coat. The embryonic root extends down to begin anchoring the new sprout and absorbing water and nutrients. Meanwhile, the embryonic shoot pokes up through the soil, bringing the first leaves (plumule) into the sunlight to begin photosynthesis.
Though tiny, the embryo contains the essential elements needed to generate the entire bean plant. It holds the genetic blueprint that guides the plant’s growth and development after germination.
The Unsung Hero: The Hilum
There is one final structure that is critical to the bean’s function, even though it gets little recognition. Called the hilum or seed scar, this is the point where the bean detached from the ovary wall as it developed. It leaves behind a scar, a weak point in the seed coat.
Though seemingly inconsequential, this tiny opening plays an outsized role. It allows moisture and oxygen to penetrate the seed coat to initiate germination when conditions are ripe. Without the hilum, the tough seed coat would be too impermeable for the seed to absorb water and sprout.
The Nutrient Density in Every Part
When we eat beans, we consume the entire package – seed coat, cotyledons and embryo. Each component contributes nutrition and health benefits:
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Seed coat – dietary fiber, polyphenols, indigestible carbohydrates that feed gut bacteria
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Cotyledons – protein, complex carbs, B vitamins, minerals like iron and zinc
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Embryo – contains antioxidants, vitamin E, and plant hormones
Altogether, the parts inside a single bean give us a powerhouse of protein, fiber, micronutrients, and bioactive compounds – not bad for a humble seed!
Opening Up a World of Possibilities
We often overlook beans as a common fixture in soup pots and tacos. But when we explore what’s inside, we uncover a complex, nutrient-dense food that supplies energy, nutrition, and health benefits far beyond its size.
From the protective seed coat to the nutritious cotyledons and tiny powerful embryo, every part of the bean works in synergy to nourish our bodies and fuel our lives. Understanding the inner workings can give us an appreciation for the genius contained within.
So the next time you enjoy a bean, think about the fascinating anatomy that makes it possible: the baby plant ensconced in its food supply, encased in a protective shell imbued with fiber. Though small, beans open up a world of culinary possibilities and nutritional potential. Now go eat some beans!
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What are the parts of a bean seed?
- Jar
- 8 pinto bean seeds
- Distilled water
- Refrigerator
- Paper towel
- Magnifying glass
- Knife
- 5 small cups
- Paper
- Pencil
- 5 pots
- Soil
- Spray mister
- Put the eight seeds in the jar and cover them with distilled water. Take the beans out and put them on a paper towel after 24 hours.
- To make the beans easy to open, make sure they are wet. Remove the outside of the bean. It’s called the seed coat, and it keeps the bean inside safe. Step one: Put your nail on the rounded edge of each bean half and spread them open lengthwise.
- Use a magnifying glass to look inside. What do you see? Draw the inside of each bean and number each half from 1 to 16. Do different bean plants look different inside?.
When you look inside a bean, it’s not just empty space in there. There are different parts that make up a bean that you can see very well with your magnifying glass.
The cotyledon is the largest part of the inside of the bean. It stores a lot of the food for the growing bean. The cotyledon on a bean seed is like the yolk on an egg and the umbilical cord on a baby. It gives the seed food.
At the top of the cotyledon is the epicotyl. This is the beginning of the bean’s shoot and will eventually form the leaves. Look closely. Can you see what will form the bean’s future leaves? Just under the epicotyl is the hypocotyl. This is the beginning of the bean’s stem. The radicle is under the hypocotyl. This is the beginning of the bean’s roots. A whole baby plant is nestled inside that tiny, growing bean seed.
A bean needs water to grow. In the beginning, it takes this in through a tiny opening called the micropyle in the hilum. The hilum is the scar on the side of the bean that shows where it was attached to its parent plant. The young bean plant starts to form inside the bean seed when the bean germinates, or starts to grow. It uses the starch that’s in the cotyledon as food.
Want to make your experiment last longer? Soak 5 new bean seeds overnight to add to the one you already have. For each bean, cut off the bottom half of one cotyledon, the bottom half of both cotyledons for another bean, ¾ of the cotyledon for another bean, and the whole cotyledon for the last bean. This will leave only the embryo. Leave one unaltered bean plant as the control.
Label your pots like this:
- 100%—Do not cut away any part of the cotyledons.
- 75%—Cut away the lower half of one cotyledon.
- 50%—Cut away the lower half of both cotyledons.
- 25 percent of the cotyledons should be cut off, but one-fourth of them should still be attached to the embryo.
- 0%—Cut away both cotyledons, leaving only the embryo.
Plant these seeds in soil in five pots and see how each one grows. Mist the beans daily. Remember what the cotyledon gives to a plant. Which one will grow the best?.
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See what’s inside a bean, how it grows, and the start of a beanstalk.
What’s Inside a Bean? – #sciencegoals
FAQ
What do beans have inside?
What makes up a bean?
What’s in a bean?
What is inside of a bean called?
What is inside a bean?
When you look inside a bean, it’s not just empty space in there. A bean is made up of different growing parts, and you’ll be able to see them quite clearly with your magnifying glass. The cotyledon is the largest part of the inside of the bean. It stores a lot of the food for the growing bean.
What type of beans should one eat?
The most healthy beans are chickpeas, lentils, peas, kidney beans, black beans, soybeans, pinto beans, and navy beans. They contain a lot of fiber and proteins.
Is a bean a plant?
Broadly speaking, a bean is a seed harvested from any species of Leguminosae. This group of plants, also called Fabaceae, includes a huge variety of flowering trees, shrubs, and herbaceous plants. This wide definition uses the word bean as interchangeable with the word legume.
What is a common bean?
The common bean ( Phaseolus vulgaris) is second to the soybean in importance and is of Central and South American origin. There are numerous varieties of P. vulgaris, including many common garden types such as pole, snap, string, and bush beans.