Page 25 - Science Coursebook

2.1 Plant adaptations

Weeds in a crop
A weed is a plant that grows where people do not want it
to grow, for example in amongst a farmer’s crops, or in a
pavement. They may have to compete with crop plants for
light, water and mineral salts.

Many weeds are annual plants. This means that they
germinate, grow, produce seeds and die in less than one year.
Some weeds can do this in just a few weeks, before people can
kill them. Their seeds can survive for long periods of time in

difficult conditions – for example during a very dry summer, or
a very cold winter. Other plants without these features would Hoeing weeds in a cassava crop
not survive. in Rwanda.

Questions
A+I 2 Siberian spruce trees do all of their growing during the summer, not during
the winter. Suggest at least two explanations for this.

A+I 3 Strangler figs produce sweet, juicy fruits. Suggest how this helps their seeds to
be dispersed to a suitable place for germination.
A+I 4 Suggest how being an annual plant helps a weed to live in its habitat.

Activity 2.1

Adaptations for living in water

Organisms that live in water are said to be aquatic.
Choose an aquatic plant that grows in your country.
Possibilities include:
• duckweed (which you may have used in Activity 1.2)
• water hyacinth
• lotus.
Find out how your plant is adapted to live in water. You can
use the internet and books, but if possible you should also
study specimens of the plant itself.
Make a large diagram of your plant. Label it to explain how
it is adapted to live in its habitat.

A lotus plant growing in a
lake in Thailand.

Summary
• Plants are adapted to live in their habitats.
• Plant adaptations often help them to get light for photosynthesis.

• Annual plants grow, produce seeds and die in less than one year.

2 Living things in their environment 23