Unit on Flowering Plants Angiosperms Unit on Flowering Plants

Objectives Learn the basic structures of a flower and their functions Learn about the role flowers play in pollination and fertilization Learn about the seeds and fruits of flowering plants

Flower Structure On the right is a model of a flower and its different parts. Learn the parts and their functions. Click each question mark to look at the individual parts. Click picture on top to see more pictures of flowers.

Parts of a flower: Petals- colorful part—(function: attracts pollinators) Sepals- leaf-like structures that encircle the stem (function: protects) Stamen- male part of flower Pistil- female part of flower

Stamen The stamen is the male reproductive organ. Made of 2 parts: Filament– holds anther into the air to help release pollen Anther—produces the pollen (sperm) Anthers Filament Explain that anther arrangement varies with each flower, and that pollen contains two types of cells: a tube cell and sperm cells. Talk about the two parts of the stamen: anther and filament. The tube cell leads to ovary and the sperm fertilize the ovule inside the ovary. The process will be shown later.

Pistil The pistil is the female reproductive organ. It receives the pollen Made of 4 parts: Ovary- forms the egg Stigma- where the pollen sticks Style- provides tube down to ovary (pollen tube) Ovule- in ovary-forms the seed Explain the role of each part of the pistil, and the process of the sperm fertilizing the ovule, inside the ovary.

Two types of flowers: 1. complete flower– has male and female parts on the same flower (has pistil and stamen) 2. incomplete flower– missing a male or female part (ex. Squash have separate male and female flowers)

Pollination Pollen Pollination is the transfer of pollen from the anther to the stigma. Why is there more pollen than eggs? Increases chances of fertilization occurring (not all pollen makes it to the egg) Explain again that petals attract pollinators. Pollination may be carried out naturally or artificially. Talk about different ways.

How is pollen transferred? 1. wind or water 2. by insects/birds feeding on nectar 3. by pollinators attracted to bright colors or scent

Path of pollen cells through the pistil Tomato ovary with ovules Fertilization The process of the sperm of the pollen grain fertilizing the ovule inside the ovary. Path of pollen cells through the pistil Detail the pollen path and explain that after fertilization, the ovule becomes a seed. There is more on that later. Tomato ovary with ovules

Steps of fertilization: 1. pollen is transferred to the stigma by wind/water or pollinators 2. Pollen goes down the pollen tube to the ovary (egg) 3. The sperm fertilizes the egg forming a fertilized egg called a endosperm 4. After fertilization, the sepals, petals, anthers and upper pistil fall off (wilt) 5. The wall of the ovary hardens to protect the embryo and a flesh develops around it to nourish it called a fruit

Tomato fruit with seeds Formation of a seed When the ovule is fertilized, it becomes a seed and is enclosed in a fruit. Tell class that in many flowers there may be more than one ovule, like in the tomato fruit. The ovary begins to change to form into a fruit. Explain that a seed is an embryo of a future plant. There are two types of embryos in angiosperms: monocots and dicots Tomato fruit with seeds

Peanuts and beans are dicots Monocots Dicots have two cotyledons present. In monocots, there is only one cotyledon present. Tell the definition of a cotyledon. Explain other ways you can tell if a plant is a monocot or dicot, such as: leaf pattern and number of petals present. Click bean pod to go back. Peanuts and beans are dicots Corn is a monocot

The End! Give reading assignment for next unit.