What Do Plants Need to Grow

Learning Objectives | National Science Education Standards
Background Information | Pre-Visit Activities
Inquiry Activities at the Garden | Suggested Galleries
Post-Visit Activities | Resources

Learning Objectives

• Plants make their own food in a process called photosynthesis.
• Photosynthesizers support all other species.
• Leaves are green because of tiny chloroplasts, a plant’s food factories.
• Using energy from the sun, plants combine water and carbon dioxide to make food.
• Plants get minerals, not food, from soil.
• Plants transport minerals and water up from the roots using tubes called xylem, and transport food from the leaves to the rest of the plant through tubes called phloem.
• Plants absorb carbon dioxide and give off oxygen through tiny pores called stomata.

National Science Education Standards

• Understand characteristics and life cycles of organisms.
• Understand the diversity and adaptations of organisms.
• Understand the process of scientific inquiry.

Background Information

Plants can make their own food. Other life forms, including humans, depend on plants for food, clean air, and many other resources. In photosynthesis, plants use the sun’s energy to combine water and carbon dioxide inside the chloroplasts to make sugar and oxygen, according to the following equation:

Plants release oxygen as a by p roduct. Plants can photosynthesize without soil— even in water or air.

• Soil provides water and minerals needed to keep plants healthy.
• Water is needed for photosynthesis, and to help plants transport nutrients.
• Xylem is a system of tiny tubes that carry water and mineral nutrients up to the leaves.
• Phloem is a system of tubes that carry food and waste away from the leaves.
• Roots absorb minerals and water from the soil.
• Sunlight is the energy source needed to make food.
• Chlorophyll is a green pigment that captures the sun’s energy to make food.
• Carbon dioxide is a waste gas given off by animals and used by plants to make food.
• Oxygen is a gas given off by plants. It is essential for most species survival.
• Stomata are tiny openings in leaves through which gasses are exchanged.

Pre-Visit Activities

• Two weeks before your trip, place a plant near the window and observe the leaves bending toward the light.
• Experiment with other plants, exposing some to light and some to darkness. Ask students to hypothesize about what will happen.
• Experiment with plants, comparing the outcome when one is watered and one is not.
• Using hand lenses and fresh leaves, find the stomata, visible on the underside.
• Explain that plants cannot move around and have no mouth to use in eating. Ask students to theorize how plants get the resources that they need to survive.

Inquiry Activities at the Garden

• Observe, compare, and describe plants growing under various conditions (sun, shade, indoors, outdoors, in a pot, in water).
• Compare and contrast plants that thrive under different conditions. How do different characteristics help the plants survive?
• Find plants growing without soil (check The Con Edison Pond Gallery or The Vincent Astor Foundation Sun, Dirt and Water Gallery)—how can they survive?
• Search out leaves that have colors other than green—can these leaves photosynthesize as well as leaves that have more green?
• Locate plants that have yellow or withered leaves; hypothesize what may be the cause—are they getting enough sun, air, water, and minerals?
• Write a recipe for plants to make food; list ingredients and supplies needed.
• Search for exhibits illustrating photosynthesis and water transport.
• Since all green parts of a plant can photosynthesize, what surprising parts of the plant besides leaves make food?

If we can’t watch a plant photosynthesize, then how do we know it happens?

How does a plant change when it is making lots of food? How could you prove this? Since plants make food with their leaves, do deciduous trees make food in winter? If not, what else can you guess they are not doing? How do plants surv i ve when they cannot make food? Can plants store food? When we eat plants, are we eating their food stores? How are the minerals that a plant needs similar to vitamins that people need? Are they the same as food? Could you live on vitamins alone?

Suggested Galleries

• The Vincent Astor Foundation Sun, Dirt and Water Gallery
• Arthur Hays and Iphigene Ochs Sulzberger Meadow Gallery
• The Hecksher Foundation for Children’s Wonder Gallery
• The Con Edison Pond Gallery
• Meadow Maze

Post-Visit Activities

• Make a class diagram or model of the process of photosynthesis. List the
  ingredients, how they enter the plant, and the final product and by products.
• Plant seeds and record their progress. Compare different growth rates and leaf shapes of different plants (such as radishes, corn, and beans).
• Set up experiments comparing plant growth in varying light and water conditions.
• Make models of xylem and phloem with straws.
• Place celery in colored water to observe water moving through the xylem. Predict what will happen; then discuss the results.

Resources

• Romanova, Natalia. 1989. Once There Was a Tree. Topeka, Kans.: Puffin
  Publishing.
• The Visual Dictionary of Plants. 1992. New York: DK Publishing.
• Johnson, Sylvia. 1986. How Leaves Change. Minneapolis, Minn.: Lerner
  Publications.