PlantsA Freshmen Overview

Ya dig.

What are plants?Plants are

Multicellular: made of more than 1 cell Photosynthetic: make food and energy from sunEukaryotes: cells have membrane bound

organelles

Their cells are surrounded by a cell wall made of cellulose.

Most reproduce sexually (pollen), but some can reproduce asexually (spores).

Evolution: Where do today’s plants come from?

Ancestors of today’s plants date back 450 million years ago.

Plants evolved from living in an underwater environment to living on dry land. They still required lots of water to survive so retaining water was very important.

Plants also adapted to have a stronger structure so that they could hold themselves up in order to take in the most amount of sunlight possible to start photosynthesis.

Bryophytes & Tracheophytes

Two groups emerged based on their structures, bryophytes and tracheophytes.

Bryophytes (mosses): Have NO vascular tissue. Must live in very wet areas and need a lot of water to survive . They stop growing during dry spells.

Bryophytes & Tracheophytes cont.

Tracheophytes: the first true land plants and have vascular tissues that transport water and nutrients to help the plants be more able to live in different places.ferns Gymnosperms: plants with cones: conifers,

evergreens Angiosperms: flowering plants

Gymnosperms and Angiosperms

Gymnosperms (evergreens, conifers) introduced the world to seeds, cone-shaped structures that hung on the outside of the plant.

Angiosperms (flowering plants) mature more quickly than gymnosperms by the use of flowers and seeds as reproduction tissues.

Adaptations for landRoots: They anchor the plant into the ground

and absorb nutrients and water from the soil.

Leaves: Broad and flat leaves allow more surface area to take in sunlight for photosynthesis and little openings in the leaf called stomata for gas exchange and preventing water loss

Vascular Tissue: Xylem and phloem carry nutrients and products of photosynthesis through the plant to where they need to go.

Adaptations for land cont.Stems: Hold up leaves to capture as much light as

possible.

Gametes and spores: Zygotes that a fertilized through a sperm grows into a sporophyte, creates spores through meiosis. The spores disperse and create gametophyte plants that can either produce sperm or be fertilized by them.

Pollen and Seeds: Pollination through pollen grains that produce sperm is carried by insects or the wind. Fertilization occurs when the female flower come in contact with the pollen grain

Alteration of Generation

Angiosperms

Gymnosperms

Ferns Mosses