Plants Provision for Life Chapter 2 7 th Grade
Lesson 2.1- Structure of Flowers Pistil- female reproductive structure Stigma- sticky top part. Traps pollen. Style- slender tube connecting stigma and ovary. Ovary- large rounded bottom. Contains ovules. The ovary develops into fruit. Ovules- contain egg cells, which become seeds when fertilized. Stamen Anther Filament Ovule Stigma Style Pistil Ovary Petal Sepal
Structure of Flowers Stamen- male reproductive structure Anther-knob like structure at the top. Produces pollen. Filament- thin stalk that supports anther. Pollen- contains sperm cells. Stamen Anther Filament Stigma Style Pistil Ovary Ovule Petal Sepal
Structure of Flowers Petals- brightly colored and scented to attract pollinators. Sepal- leaf-like structures that surround the base of the flower. Encloses and protects the developing flower bud before it blooms. Receptacle- enlarged upper portion of a flower s stem. Stamen Anther Filament Ovule Stigma Style Pistil Ovary Petal Sepal
Structure of Flowers Most flowers have both male and female reproductive parts. Some though, only have one. Pistillate- containing on the pistils. Staminate- containing on the stamens.
2.2- From Pollen to Seed Pollination- the transfer of pollen from the anther to the stigma. Insects, birds, and small animals (called pollinators) aid in pollination. These animals are drawn to plants because of their color or the sweet smell of their nectar. Fertilization- uniting of a sperm cell from a pollen grain with an egg cell in the ovary. This leads to the formation of a seed.
Self-Pollination- being pollinated by its own pollen. Cross-Pollination- the transfer of pollen from one flower to another. Embryo- the fertilized egg produced when the egg cell and sperm cell combine in fertilization.
Seed Development Seeds have 3 main parts: Embryo- the beginning of a new plant. Endosperm- stored food. Seed Coat- surrounds and protects the seed until it can grow.
Seed Development When sperm and egg unite, the resulting embryo is a miniature plant made of a plumule, radicle, and one or two cotyledons. Plumule- tiny shoot that will become the stem and leaves. Radicle- the small root that will develop into a root system. Cotyledons- structures designed for food absorption and storage.
Monocots and Dicots Monocots- have one cotyledons. Dicots- have two cotyledons.
Lesson 2.3- Plant Process Pollination Fertilization Germination- early growth of the plant Occurs after the seed coat is softened by moisture. Plant grows and flowers are formed. Flower drops petals and ovary develops into a fruit- a ripened ovary. Fruits protect the maturing seeds and help with dispersal.
Dispersal 2 Types of Dispersal Mechanical- fruits bursting and releasing seeds. Agent- dispersal through a secondary agent - animals, birds, wind, water, etc.
The Seed Grows Up Requirements for Germination Moisture Favorable temperature Oxygen **Seeds will remain dormant if these conditions are not met.
Stages of Germination Seed begins to swell by absorbing water. Embryo pushes the radicle through the softened seed coat and into the ground. Plumule emerges above the surface of the ground and the radicle grows into a root system. When the plant no longer depends on the cotyledons for nutrients, it is a seedling, and germination has ended.
Plant Life Spans Annuals- are plants that complete a life cycle in one growing season. Biennials- complete their life cycle in two years. In the first year, they germinate and grow roots, short stems, and sometimes leaves. In the second year, they grow new stems and leaves, produce flowers and seeds, and die. Most have a taproot- a large central root. Perennials- live for more than two years.
2.4- Flowers of Meadow and Garden Angiosperm- flowering plant- seeds develop inside the ovary of a flower. Gymnosperm- seeds are housed in a cone.
Angiosperm Families Composite Familymany small flowers grouped together in a head. Tubular disk flowers form the head s center, and petal-like ray flowers surround the center. Ex: asters, sunflowers, daisies, black-eyed susans, artichoke, lettuce