Engaging with Nature
Plant Needs
Plant Parts
Like all organisms, plants have both internal and external parts that allow for growth, survival, behavior, and reproduction. Some of these parts are microscopic (not visible to the human eye) and some are macroscopic (visible to the human eye).
Leaves
Leaves are the primary photosynthetic organ of plants. Leaves take in light and convert it to energy. Different leaf shapes, sizes, and textures play a part in a plant’s photosynthetic rate (how quickly the plant converts sunlight into energy). Leaves can protect a plant from pests, control air flow, prevent water loss, provide shade, and direct water from or to the plant. Leaves can either be simple or compound.
Leaf parts
Leaves are composed of a petiole and leaf blade. The leaf blade is made up of many smaller parts. Use this interactive image to learn more about the petiole and the parts that make up the leaf blade.
Petiole. The petiole attaches the leaf to the stem. Sometimes the petiole can look like a stem, but it is actually part of the leaf. Petioles can be long or short, wide or narrow!
Lamina. The lamina is the surface part of the leaf. It has the most area of any leaf part.
Midrib. The midrib supports the leaf from the middle. It is important for helping the leaf keep its shape!
Vein. Every leaf has a system of veins, and this system can look very different among leaves from different plants. Leaf veins have different patterns, but all leaf veins do the same job. Leaf veins are responsible for moving the nutrients and water that come up from the stem around the leaf. Leaf veins are also responsible for moving the sugars (created by the leaf during photosynthesis) to the stem.
Cuticle. The cuticle is a waxy layer that covers the outside of the leaf, and cloaks it in a protective layer. This protective layer acts as a sort of armor for the leaf.
Leaf Investigation
What are the parts of a leaf and why are the parts important for plant growth and survival? Make observations about the parts and features of leaves and make inferences about how leaves help plants grow and survive.
Make your Own Leaf Skeleton
Leaf skeleton art was a popular activity for Anglo-American women in the 19th century. Try making your own!
Stems
Stems connect the roots to the leaves and flowers and act as transport routes for water, nutrients, and food. Stems support plants as they grow toward light and hold the leaves and flowers in positions to capture light and attract pollinators. Stems can hold large amounts of sugars for the plant to use when they are unable to photosynthesize, so stems are also food storage organs for plants.
There are two types of stems: branching and unbranching (apple tree vs. palm tree). Some stems are often not seen because they are below the ground (potato). Stems can be either herbaceous (soft) or woody (hard).
Stem parts
Stems have four parts, and some of these parts are “shared” leaf parts. Use this interactive to learn more about the parts of a stem.
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Node- Nodes are the point of attachment for leaves, buds, roots, and other stems. Nodes help plants form buds, roots, leaves, and branches.
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Internode- Internodes are the space between the nodes on the stem and are the connection between nodes. Internodes transport water, nutrients, and sugars and can be very short or very long depending on the plant species.
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Bud- Buds can be either terminal/apical or lateral/axillary. Apical buds are at the end of a stem, and they are the primary growth point of the plant. Buds produce hormones that affect how the buds, leaves, and roots grow. Axillary buds develop at the nodes and give rise to new stems or flowers. Axillary buds help the plant grow outward (laterally) and develop leaves and flowers.
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Leaf petiole- Leaf petioles are thin stalks that attach the leaf blade to the stem at a node. They support the leaf and help the leaf orient to maximize light interception. Petioles also help to transport water, nutrients, and food to the cells in the leaf.
Stem Investigation
What are the parts of a stem and why are these parts important for plant growth and survival? Make observations about the parts and features of stems and make inferences about how stems help plants grow and survive.
Roots
Roots provide nutrients and water from the soil to the stems, leaves, flowers, and fruits. Roots also provide stability and anchor plants as they grow toward light. Roots can be an energy storage system to hold plant “food” (carbohydrates) for later use. Plants can have many different types of root structures. Taproots are large primary/dominant roots that help plants reach deep reserves of water and nutrients in the soil. Filamentous roots do not have a single dominant (primary) root and spread in all directions, usually close to the soil surface. Adventitious roots are roots that can form along the nodes of the plant and can aid in climbing or stabilizing the plant. These roots can also help plants find water and nutrients or provide extra air to the root cells.
The Life of Radish
Use this interactive image to explore the changes to the radish root throughout its life.
Lisa Pompelli, Life of Radish, 1994, The Huntington Library, Art Museum, and Botanical Gardens | All rights reserved by artist
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Germination- Inside each radish seed, there is a tiny root called a radicle. In germination, the primary root descends into the earth.
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Growing downward- The taproot grows downward and other roots branch off. The root tip on each of these roots absorbs nutrients.
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Photosynthesis- The leaves are above ground and are starting to photosynthesize. The plant now has access to the sugar it makes from sunlight.
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Storage in the root- The plant uses some of these sugars to help it grow bigger, and stores the extra sugars in the root.
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The fattening of the root- The root gets fatter and juicier as more and more water, sugar, and nutrients get stored in the root.
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Maximal juiciness- If we were harvesting this radish for food, we would want to pull it up from the ground at this stage. This stage is when the root has stored as much sugar, water, and nutrients as it is going to.
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Using the stored resources- Growing flowers and fruit takes a lot of energy! The radish transports sugar, water, and nutrients up the stem to help the plant grow the flowers it needs for reproduction.
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All used up- Now that the radish has shot its stem upward and grown flowers, its root is tough. The root still draws in nutrients and it still anchors the plant in the earth, but it no longer stores extra sugar, water, and nutrients for the plant.
Root Investigation
What are the parts of a root and why are they important for plant growth and survival? Make observations about the parts and features of roots and make inferences about how roots help plants grow and survive.
Flowers
Plants that grow flowers are called angiosperms. Flowers are reproductive structures. Flowers are important for attracting pollinators, promoting genetic diversity through cross-pollination, and housing plant embryos. Flowers are modified buds. Flowers can be either male or female, or they can have both male and female reproductive structures. Flowers have coevolved with animals.
Flowers are greatly diverse and can be many shapes, sizes, and forms depending on the species. Some of these forms include: multiple flowers on a larger floral axis (inflorescence); single, solitary flowers; flowers with radial symmetry (all the way around); and flowers with bilateral symmetry (down the center).
Flower Parts
Flowers have three major parts: perianth, pistil, and stamen. Use this interactive to learn more about these major parts of a flower.
Daylily 'Elves' (Hemerocallis 'Elves')
- Perianth- The perianth consists of the sepals/calyx and the petals/corolla. These terms vary based on the type of flower; for example, lilies have indistinguishable sepals and petals. The corolla is also referred to as a cluster of petals. Collectively these parts are typically used to attract pollinators.
- Pistil- The pistil is the collective female flower parts made up of the stigma, style, and ovary. The stigma is the receptor for pollen grains to begin fertilizing the flower. The style connects the stigma and ovary and is where the pollen tube extends through to reach the ovules in the ovary and to create a plant zygote. In some plants, individual ovules are visible to the naked eye, but in many plants, they are not visible without magnification.
- Stamen- The stamens are the male reproductive parts of the flower. The stamen consists of the filament and the anther. The anther is the pollen sac where pollen is held. The filament orients the anther so that pollen is transferred when pollinators visit the flower.
- Peduncle- Attaching the flower to the stem/node is the peduncle, which helps orient the flower. The receptacle is attached to the peduncle and holds all the flower parts we traditionally think of when we talk about flowers.
Flower Investigation
What are the parts of a flower and why are they important for plant reproduction? Make observations about the parts and features of flowers and make inferences about how flowers help plants reproduce.
Fruits and Seeds
Most plants grow from seeds, and many seeds develop in a fruit. There are many different types of fruit that take many different forms with varying arrangements of the parts that make up the fruit. Similarly, seeds can vary in size and shape depending on the species of plant. Fruit is the primary means of seed distribution in flowering plants.
Many vegetables are actually fruit! Fruit contains seeds. For example, zucchini, tomato, and bell peppers are all fruit.
Fruit Parts
Collectively, the fruit parts, not including the seed, are referred to as the pericarp. Use this interactive image to learn more about seeds and the parts that make up the pericarp.
Canteloupe (C. melo var. reticulatus) | Jim Folsom (photography)
- Seeds contain the genetic material of a new plant. The parts of the seed are the embryo, endosperm, and seed coat. The embryo is a potential new plant that is ready to begin growing once the environmental conditions are ideal. The seed coat is the outermost layer of the seed and protects the embryo inside the seed and prevents it from drying out or being damaged by seed predators and pests. The endosperm provides sugar and nutrients for the embryo. In this image, only the seed coat is visible.
- The epicarp is the outermost tissue of the fruit, like the rind of an orange or the skin on an apple. The epicarp is part of the pericarp.
- The mesocarp is the fleshy and edible part of a fruit and typically contains a lot of water, like the flesh of a mango or peach. The mesocarp is part of the pericarp.
- The endocarp is the inner part of the fruit usually surrounding the seed. For example, the endocarp in peaches is the outer coating surrounding the pit. The endocarp is part of the pericarp.
Seed Investigation
What are the parts of a seed and why are the parts important for plant growth and survival? Make observations about the parts and features of seeds and make inferences about how seeds help plants grow and survive.
Fruit Investigation
What are the parts of a fruit, and why are they important for plant growth and survival? Make observations about the parts and features of fruit. Make inferences about how fruit helps the plant grow and survive.