Plants: parts and needs

Plants are living things. Most flowering plants have the same main parts: roots, a stem, leaves and flowers. Each part has its own job. To grow well, a plant needs light, water, air, warmth and nutrients from the soil – and room to grow.

Key facts

  • Roots hold the plant in the ground and take in water and nutrients from the soil.
  • The stem holds the plant up and carries water from the roots to the leaves and flowers. A tree’s strong, woody stem is its trunk.
  • Leaves use light from the Sun to make food for the plant.
  • Flowers make seeds, which can grow into new plants. Many flowers are bright and sweet-smelling to attract insects.
  • A plant needs light, water, air and the right warmth to grow and stay healthy. In the dark it grows pale and weak; without water it wilts (droops).
  • Deciduous trees, like oak and beech, lose their leaves in autumn. Evergreen trees, like pine and holly, keep their leaves all year round.

Worked examples

Example 1

Name the four main parts of this plant and say what each one does.

  1. Under the ground are the roots. They hold the plant in the soil and take in water and nutrients.
  2. The stem holds the plant up and carries water up to the leaves and the flower.
  3. The leaves use sunlight to make food for the plant.
  4. The flower makes seeds that can grow into new plants.

Answer: roots: hold the plant and take in water; stem: holds it up and carries water; leaves: make food; flower: makes seeds

Example 2

Two bean plants get the same amount of water. One is on a sunny windowsill and the other is in a dark cupboard. How will they look after a week?

  1. Everything is the same except light, so any difference is caused by light.
  2. The plant in the light can make food in its leaves. It grows strong, with green leaves.
  3. The plant in the dark can’t make food. It grows tall and thin, stretching for light, with pale yellow leaves.

Answer: the plant on the windowsill is green and healthy; the plant in the cupboard is pale, yellow, thin and weak

Example 3

A white carnation stands in a glass of water with blue food colouring. What happens after a day, and why?

  1. The bottom of the stem takes in the blue water.
  2. Tiny tubes inside the stem carry the water up the plant.
  3. The water reaches the petals, and the blue colour shows in them.

Answer: the petals turn blue, because the stem carries the coloured water up to the flower

Example 4

A sunflower was 12 cm tall. A week later it was 19 cm tall. How much did it grow?

  1. Growth = the new height − the old height. 19 − 12 = 7
  2. It grew 7 cm.

Answer: 7 cm