Read the following text to answer questions number 50 to 53.

    A cactus (plural: cacti) is any member of the plant family Cactaceae, native to the Americas. They are often used as ornamental plants, but some are also crop plants. Cacti are grown for protection of property from wild animals, as well as malty other uses.

    Cacti are unusual and distinctive plants, which are adapted to extremely hot environments, showing a wide range of anatomical and physiological features which conserve water.

    Cacti come in a wide range of shapes and sizes. Many cactus species are night blooming, as they are pollinated by nocturnal insects or small animals, principally moths and bats. Cacti range in size from small and globular to tall and columnar.

A cactus can be easily found in front of many houses because it is often used as a/an ... plant.