Chapter 8 : Flowers and Fruit
Flowering plants come in three basic types:
Flowers may be single, or grouped together to form an inflorescence. The main types of inflorescences are:
- annuals grow in a single season or year and die after they flower. They only flower once.
- biennials grow for two seasons, and flower and die the second year. They only flower once.
- perennials grow for many years and can flower repeatedly.
Flowering plants are either :
- catkins - hang down with flowers close together.
- umbels - have several flowers all attached to the same point in a semi-circle.
- spike - has flowers joined directly to a tall stem
- raceme - has flowers on stalks alternating up the stem
- corymb - has flowers that form a flat surface, yet are attached to different points of the stem.
Plants actually measure night length, not day length.
A flash of bright light in the night will reset the plants internal clock.
Short day ( long night ) plants : flower in winter/spring eg poinsettia, strawberry
Long day ( short night ) plants : flower in summer eg lettuce, tomato
Day neutral plants : flower any time of year eg peas, corn, rice
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 David.Byres@fscj.edu