Bulbs Lesson

Champaign County Juvenile Detention Center Master Gardener Community Garden

Bulbs Lesson

Time 1 -1.5 hours

Overview The term bulb is used by many people to refer to plants that have underground, fleshy storage structures. Only some of the plants commonly called bulbs are actually bulbs. The term bulb refers to plants that complete a part of their life cycle as an underground storage unit. This lesson introduces flowers and food crops, with underground storage structures, such as tulips and onions. The types of storage structures we will discuss are true bulbs, corms, tubers, and rhizomes.

Objectives Students will: • Review basic plant structures (leaf, stem, root, flower/seed) • Discuss the different types of bulbs with photos and examples: o True bulb: tulip, daffodil, and onion o Corms: crocus o Rhizomes: iris o Tubers: potato • Discover the difference between bulbs and other underground storage structures like carrots.

Supplies • Plant Parts illustration • Bulb Parts illustration • Physical examples of tulip, iris, crocus, potato, onion, carrots, and beets • Daffodil bulbs for planting activity • Soil, containers, and gloves for planting

Snack 16 oz. container of onion dip 1 – 2 bags of potato chips (Jays or Mikesells) 1 large bag of carrots, 1 head of broccoli, 1 lb. bag of sunflower seeds Juice/water

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Activity Review of true bulbs, tulips and onions, vs. tubers, like potatoes. Compare and contrast bulbs with vegetables, like carrots. Bulb planting Snack Chat: Discuss other plant parts that we eat like roots, seeds, and flowers.

Sources http://urbanext.illinois.edu/gpe

Bulbs

DO: Begin by introducing yourself and the other Master Gardeners by first names.

SAY: Good afternoon. We are a group of Master Gardeners of Champaign County here to provide a gardening program today at JDC. In the fall and winter months we come every other week to give a lesson on plants, eating right, and taking care of the planet. In the spring and summer we work together with you to plant and maintain a vegetable and flower garden in the outside rec area. (depending on time… I became interested in gardening because… Does anyone else have gardening experience or a relative who gardens?)

Today’s lesson will be… I am… with other volunteers….(introduce themselves). (Participants may introduce themselves also.)

DO: Pass around the Plant Parts illustration as you discuss the following plant parts.

SAY: Roots: Roots anchor the plant and help it absorb water and nutrients needed for growth. They can also store sugars and carbohydrates that the plant uses to carry out other functions.

Stems: The stem carries water and nutrients taken up by the roots to the leaves. The food produced by the leaves moves to other parts of the plant. Stems also provide support for the plant allowing the leaves to reach the sunlight that they need to produce food.

Leaves: Leaves are the food making factories in plants that use a process called photosynthesis. In this process carbon dioxide, water, and light energy are changed into glucose (sugar) with special help from chlorophyll. Chlorophyll is what makes plants green in color. Photosynthesis supplies food for the plant, and oxygen for other forms of life.

Flowers: Flowers not only look pretty, but are important for making seeds. They contain the plants reproductive organs.

Fruits: The fruit is the ripened part of a plant that contains the seeds. Many plants we call vegetables, such as tomatoes and cucumbers, are really fruits.

Seeds: Every seed is a tiny plant embryo with leaves, stems, and root parts waiting for the right conditions to make it germinate and grow. The seed also contains the food supply used by the tiny plant to help it grow. Corn, beans, and rice are examples of seeds we eat.

What other ways do plants have to store food? • They store food in roots, like carrots. Some plants store food in swollen underground stems like tulips and onions. These plants are called bulbs.

The swollen stem of a bulb has a little plant inside that is dormant, or sleeping, and surrounded by stored food and covered with a protective outer covering. Most bulbs grow and flower for a period of time and die back to ground level at the end of the growing season.

Can you name some flower bulbs?

DO: Allow some responses before continuing.

SAY: There are many types of bulbs. True bulbs, like tulips, daffodils, and onions, contain complete miniature plants. The plant is surrounded by fleshy scales and attached to a basal plate. The scales are swollen stems filled with carbohydrates to nourish the young plant.

A bulb is a “packaged plant” with a complete miniature plant inside and wrapped in a papery brown tunic for protection.

DO: Show the tulip or daffodil bulbs and onion bulbs cut in half. Pass around the Bulb Parts illustration.

SAY: If a bulb is sliced in half horizontally, you will see rings formed by the scale leaves. If you slice into a bulb vertically you should find leaves, stems, and even flower buds.

The flower is already inside the bulb!

DO: Pass around the tulip bulbs for everyone to see.

SAY: What are the parts of a bulb?

A true bulb has a basal plate where the roots grow. The tunic is papery brown and protects the scales and the shoot. The side buds develop into small bulblets which will grow into new bulbs.

Now that you have discovered the various parts of the bulb, let’s find out what each part does.

What does the tunic do? • It protects the bulb from damage and drying out.

The scale leaves? • They hold stored food and carbohydrates.

The leaves, flower buds, and stem make up the new plant that will bloom next year. The basal plate is the area that produces roots.

After the bulb flowers in the early spring, the leaves stay green for a short time to nourish the bulb and to store food for next year.

The leaves yellow and die off by early summer. The bulb is then dormant during the heat of summer and grows roots in the fall.

Fall is the best time to plant spring bulbs like tulips.

Bulbs are often planted in large dramatic groups or around other plants. These groups of bulbs are “naturalized” or planted in a way that looks natural. Bulbs are planted at a depth three times their height. This protects them from the hot and cold or animals.

New bulbs form around the original bulb from little side buds. When these bulbs multiply and become crowded, the flowers get smaller every year.

DO: Pass out the crocus, iris, and potato when discussing the following types of bulbs.

SAY: What are some other types of bulbs?

Corms A corm is a swollen stem base, but it does not have visible storage rings when cut in half. This is how you can tell it apart from a true bulb, which does have storage rings. The corm contains a basal plate and a thin tunic.

DO: Pass around the crocus.

SAY: Rhizomes A rhizome is a swollen stem that grows horizontally under the surface of the soil. On some plants this type of rooting structure can be very invasive, which means it can take over an area and choke out other plants.

DO: Pass out the iris, but be sure to leave it in the bag because the sap can make you sick if you ingest it.

SAY: Tubers Tubers are short, fat underground stem tissue with growing points called eyes. Potatoes come in several shapes and colors.

Have you ever seen a potato sprouting? When the potato turns green and sprouts you should avoid eating it because it can make you sick.

DO: Pass around the potato and point out the eyes.

Activity

Review of true bulbs vs. tubers.

Hold up the potato and onion. How can we figure out which one is a true bulb? Ask questions to determine if it is a swollen root or stem. The tuber differs from the true bulb because it does not have scales, a tunic, or a basal plate.

Do you think it is a good idea for plants to store their food in a bulb?

Contrast bulbs with vegetables like carrots. How are bulbs different from plants that store food in an underground root? Bulbs are modified underground stems that store food for the plant, and vegetables like carrots and beets store food in modified roots.

Bulb planting Plant some bulbs like tulips, crocus, or daffodil at appropriate depths in containers or in the garden beds.