IMPORTANCE OF PLANTS

Importance of Plants

• Oxygen• Food/feed• Medicine– http://www.youtube.com/watch?v=6iEOTB1UjjQ

• Absorb Carbon Dioxide• Decoration (Aesthetic)

PLANT LIFE CYCLES

Plant Life Cycle• Annual– Goes from seed to producing seed in one growing season– Ex. Corn, beans

Summer Annuals

• Summer annuals germinate in the spring. Summer annuals produce leaves, flowers, and seed before dying during the summer or fall. – Many crops and garden plants are annuals.

– Corn, soybeans, rice, wheat, potatoes, and tomatoes

– Petunias, impatiens, marigolds, and zinnias

– Ragweed, pigweed, lambsquarter, crabgrass

Photo, courtesy USDA Peggy Greb

Winter Annuals

• The seed of a winter annual germinates in the fall. The immature plant overwinters as a compact rosette. Once the plant has received a sufficient period of cold treatment, it bolts.

Winter Annuals

• Bolting is a process in which the stem of a plant rapidly elongates at the time of flowering. – Flowers then develop, seeds are set, and the plant

dies. – Winter wheat

Plant Life Cycle• Biennial– Goes from seed to producing seed in two growing seasons– 1st year – vegetative growth– 2nd year – vegetative and flower growth– Ex. Carrot, burdock

Biennials

• Biennials are plants that normally require two growing seasons to produce flowers and seed before dying. – First growing season: biennials grow vegetatively.

– Next: plants go dormant and rest until the Spring

– Winter: receive a required cold treatment

– Growth is resumed in the spring of the 2nd season.

– The plants bolt, flower, produce seed, and die.

– Hollyhock, Sweet William, parsley, beets, and carrots

Plant Life Cycle• Perennial– Lives more than two growing seasons– Ex. Trees, shrubs

Perennials

• A perennial is a plant that has a life cycle of more than two growing seasons. – May take perennial plants a few years to many years

to reach reproductive maturity. – Perennials may be woody like trees

and shrubs or herbaceous.

On the flip chart(s) – create a Venn-Diagram to compare and

contrast the three types of plant life cycles

MAJOR PLANT STRUCTURES

Major Plant Structures

• Flower– Attracts insects for

pollination

• Fruit– Seed-carrying structure

Major Plant Structures

• Seeds– Produces new plants

• Leaves– Produces food/sugars

Major Plant Structures

• Stem– Supports the plant– Transports water,

nutrients and food/sugar

• Roots– Anchors plant– Absorbs water and

nutrients– Stores food