Plants have 4 Plant characteristics that they all share: Characteristics (1) Photosynthesis – Plants are green because they contain chlorophyll – Chlorophyll: green pigment that captures energy from sunlight, found in chloroplasts
– Plants use energy from sunlight to make food from carbon dioxide and water—this process is known as photosynthesis– Plants are producers—they make their own food
(2) Cuticles – Plants don’t dry out because they are protected by a cuticle – Cuticle: a waxy layer that coats most of the surfaces of plants that are exposed to air
(3) Cell Walls – Plants do not have a skeleton like animals – They stay upright and are protected because they are surrounded by a rigid cell wall – Cell wall is made of carbohydrates and proteins – Some plants form a secondary cell wall this stops them from growing larger
(4) Reproduction – Plants have 2 stages in their life cycle: sporophyte stage and gametophyte stage – In the sporophyte stage plant makes spores – In suitable environment, spores grow & these new plants are called gametophytes
– During gametophyte stage, female gametophytes produce eggs and male gametophytes produce sperm.– Sex cells cannot grow directly into new plants—a sperm must fertilize an egg– The fertilized egg grows into a sporophyte, makes more spores, and the cycle starts again
Check for Understanding What are 4 characteristics that all plants share?Photosynthesis, cuticle, cell wall, and reproduction
4 Main Groups of Plants First they can be classified as nonvascular plants and vascular plants Vascular plants are further divided into 3 groups: – (1) seedless plants – (2) nonflowering seed plants (gymnosperms) – (3) flowering seed plants (angiosperms )
Seedless Plants***2 groups of plants don’t make seeds: (1) Nonvascular Plants – Three groups of plants that lack specialized conducting tissues and true roots, stems, and leaves – Depend on diffusion to move materials from one part of plant to another – Most are small – Usually live in damp places – Don’t have true stems, roots, or leaves
– 3 groups of nonvascular plants are liverworts, hornworts, and mossesliverworts hornworts mosses
Mosses, Liverworts, and Hornworts– Have leafy stalks and rhizoids– Rhizoid: a rootlike structure in nonvascular plants that holds the plants in place and helps plants get water and nutrients– Have 2 stages to their life cycle
– Importance of Nonvascular Plants Usually the first plants to live in a new environment, such as newly exposed rock When they die, they form a thin layer of soil Hold soil in place, reducing erosion Some animals eat nonvascular plants Other animals use them for nesting material Peat mosses are important to humans because they can be dried out and burned as fuel
(2) Seedless Vascular Plants – Ferns, horsetails, and club mosses are usually much smaller than in the past— some ferns grew 8 meters tall in ancient forests! – Because they have vascular tissues, they are often larger than nonvascular plants
Ferns – Have a rhizome an underground stem from which leaves and roots grow – Fern leaves are called “fronds” – -The end of the fronds are called fiddle heads
Club Mosses – Have vascular tissue, so not actually a moss Horsetails – Stems are hollow and contain silica—gives them gritty texture – Early Americans used horsetails to scrub pots and pans
– Importance of Seedless Vascular Plants Help form soil & prevent erosion Ferns add to soil depth, helping other plants to grow Popular houseplants Fiddleheads of ferns and some horsetails can be eaten Horsetails are used in some dietary supplements, shampoos, and skin-care products Remains of ancient ferns, horsetails, and club mosses form coal, which humans rely on for energy
Check for Understanding Name & describe the 4 main groups of plants 1)nonvascular: no specialized tissues 2) Seedless vascular: ferns, horsetails, club mosses 3) Gymnosperms: nonflowering seed 4) Angiosperm: flowering seed
The Origin of Plants – Green algae may look like a plant, but it isn’t a plant – Scientists think that green algae and plants share a common ancestor because of the following similarities: Both have the same kind of chlorophyll Have similar cell walls Both use photosynthesis to make own food Both store energy in form of starch Both have a two-stage life cycle
The similarities between a modern green algae(right) and plants, such as ferns (left), suggestthat both may have originated from an ancient species of green algae.
Check for Understanding Explain the origin of plants-scientists think that green algae and plants share a common ancestor
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