Adapted from Prentice Hall
Plants are multicellular eukaryotes that have cell walls made of cellulose.
Plants develop from multicellular embryos and carry out photosynthesis using the green pigments chlorophyll a and b
Plant Life Cycle
Plants go through Alternation of Generations
During the two phases of the life cycle, mitosis and meiosis alternate to produce the two types of reproductive cells — gametes and spores.
The diploid (2N) phase is called the sporophyte, or spore-producing plant.
The haploid (N) phase is called the gametophyte, or gamete-producing plant.
In order to survive, plants need:
water and minerals
gas exchange (need CO2 & give off O2)
transport of water and nutrients throughout the plant body
The first plants evolved from an organism similar to the multicellular green algae living today.
The oldest known plant fossils, about 450 million years old, are similar to today’s mosses.
They had a simple structure and grew close to the ground.
Plants are divided into four groups based on these features:
Plants are also classified by other features, including reproductive structures and body plan.
Evolution of the Plant Kingdom
Ferns and their relatives
Mosses and their relatives
Flowers; Seeds enclosed in fruit
Water-conducting (vascular) tissue
Green algae ancestor
Moss & Fern
Mosses and their relatives are called bryophytes, or nonvascular plants.
They do not have vascular tissues, or specialized tissues that conduct water and nutrients.