Chapter 8 : Flowers and Fruit

Flowering plants come in three basic types:
  1. annuals grow in a single season or year and die after they flower. They only flower once.
  2. biennials grow for two seasons, and flower and die the second year. They only flower once.
  3. perennials grow for many years and can flower repeatedly.
Flowers may be single, or grouped together to form an inflorescence. The main types of inflorescences are: Flowering plants are either :
  1. Short day ( long night ) plants : flower in winter/spring eg poinsettia, strawberry
  2. Long day ( short night ) plants : flower in summer eg lettuce, tomato
  3. Day neutral plants : flower any time of year eg peas, corn, rice
Plants actually measure night length, not day length. A flash of bright light in the night will reset the plants internal clock.

Night length is measured using a protein : phytochrome which has two forms :
Pr ( absorbs red light ) and Pfr ( absorbs far red light ).

After pollination, the seed develops inside a fruit. Fruit is made of three layers: the exocarp is the outer layer. The mesocarp forms the fleshy tissue in the middle and the endocarp surrounds the seed.

Types of fruit

Pome - most of the fruit is formed from the receptacle (under the flower) eg pear, apple

Drupe - has fleshy fruit and a single seed with a hard endocarp eg peaches, coconut and olives

Berry - has many seeds eg tomatoes, peppers and cucumber but not strawberries!

Aggregate fruit - develop from one flower with many pistils eg strawberries.

Legumes - split along two sides eg beans, peas

Capsules - are dry fruit that have several carpels eg orchids

Nuts - have one seed and a hard pericarp eg acorns

Grains - have the fruit and seed joined closely together eg wheat, rice, barley.

Multiple fruits - come from several different flowers joined together eg pineapples.

Last edited November 2018, by David Byres