Lesson 15

 Plant reproduction is the process of producing young plants. Plants reproduce in two different ways:  Asexual Reproduction involves one parent producing genetically identical plants. Each plant is a clone or exact copy of its parents.  Sexual Reproduction involves two parents, a male and a female, producing genetically different plants. The new plants are different from each other and from the parents.

 There are several reasons why seed plants find this form of reproduction advantageous. If the environment has been stable for many generations, variability may not be as essential to the survival of the species.  Asexual reproduction which is not as complex and requires far less energy, would be preferable.  When colonizing a new area, finding a mate for sexual reproduction may be difficult or impossible.

 If the environment is particularly harsh, the more delicate or susceptible organs or stages of sexual reproduction may not be able to survive.  Many plants which inhabit such areas as deserts or arctic tundra only reproduce asexually.

RootStemLeaf The new dahlia plant grows from a root The new strawberry plant grows from the stem or runner of a parent plant. Roots and tiny new plants form at the bottom of a leaf cutting from an African violet

 Nursery and greenhouses workers produce new plants by Grafting. In grafting, the stem of the one plant grows on the root system of another plant. Experienced nursery workers are knowledgeable about which plants can be grafted and different methods of grafting. A B

 Plant A grows excellent fruit  Plant B grows strong roots  Grafting combines desirable qualities of two different plants. This allows us to combine trees that produce good fruit with trees that have strong roots.

 Name four ways that plants reproduce asexually  1 Roots  2 stems  3 Leaves  4 Grafting   What is the advantage of grafting plants?  we can mix the good traits of plants 

 Plants flowers contain its reproductive cells. Many plants have both the male and female sex organs on the same plant. In some cases they will have male and female flowers on the same plant or they can have both the male and female organs on the same flower.

 These plants are called Hermaphrodites. Some plants such as poplars have separate male plants and female plants. This type of sexual reproduction is called? Separate Sexes

 Seeds are the product of sexual reproduction in most plants. A seed is a complete reproductive package that contains an Embryo, a food supply, and a seed coat which protects it from Drying Out.

 Two groups of seed-bearing plants are Angiosperms and Gymnosperms.  Flowering plants are called Angiosperms. Seeds form inside the Flowers.  The seeds are enclosed in a case called a Pod or a shell.  Some angiosperms include: Apples, Tomatoes, and sunflowers.

 Plants that do not produce flowers are called gymnosperms.  The seeds are produced inside Cones.  The seeds are not enclosed in a case but have Coat that protects them from dehydration.  Some gymnosperms include: Pine trees and Fir trees

 Other plants such as ferns and mosses reproduce sexually without bearing seeds.

 The reproductive organs of an angiosperm are found in the Flowers.  The female reproductive organ is called the Pistil. The pistil contains 4 parts.

 The stigma is the sticky part that captures the pollen grains.  The Style is the stalk that supports the stigma.  The Ovary contains the ovules.  The Ovules are sacs containing the female gametes.

 The male reproductive organ is called the Stamen. The stamen contains 3 parts.  The Anther is where the pollen is produced and stored.  The Pollen Grains are cases containing the male gametes.  The Filament is a stalk that supports the anther.

Pollen Grains Anther Filament Style Ovary Ovules Stigma Anther

 Pollination is the process of Pollen Grains from the anther reaching the stigma of the Pistil so that seeds can develop inside a flower.  If the male and female gametes ( Egg and Sperm ) come from the same plant the process is called Self pollination.  If the gametes come from two different plants the process is called Cross Pollination.  In order for fertilization to occur, the pollen grain grows and extension called a pollen Tube. 

 A Zygote is formed when a sperm reaches an Egg. In some plants the ovary surrounding the zygotes develops into the Fruit. The fruit helps to protect and disperse the seeds.

 The transport of seeds away from the parent plant is called Dispersal.  Seeds can be eaten by Animals and fall far away as droppings.  Seeds can also stick to Fur of mammals until rubbed off.  Seeds can also be transported by the Wind and by running water.

 The process by which a plant starts to grow is called Germination.   Gymnosperms are also called Conifers because their seeds are formed inside cones.