BiologyUnit: The Plant Kingdom

How are plants different? Classified into Kingdom Plantae Characteristics common to ALL plants:

Multicellular Eukaryotic Autotrophic (producers by the process of

photosynthesis) Cells have a cell wall made of cellulose

The Two Main Groups of Kingdom Plantae Vascular Plants called tracheophytes

Plants that HAVE vascular tissues Nonvascular Plants called bryophytes

Plants that do NOT have vascular tissues Example: Mosses

***Vascular Tissue – specialized tissue that forms tube-like structures in a plant for the purpose of moving water and nutrients***

Vascular Plants Divided into two groups based on the way

they reproduce: Seedless plants (Example: Ferns) Seed plants

Divided into: Gymnosperms (Example: Pine Tree) Angiosperms

Divided into: Monocots (Examples: Grasses) Dicots (Example: Fruit Tree)

Non- Vascular Plants or Bryophytes Belong to three different divisions:

Bryophyta (The Mosses) Hepatophyta (The Liverwarts) Antheocerophyta (The Hornworts)

Do not have vascular tissue Do not have TRUE leaves, but instead have tissues that are

only a few cells thick Do not have roots…instead, they have rhizoids (used to

anchor them in place) Water and dissolved nutrients must move through the non-

vascular plant by diffusion and osmosis This process is a very slow way to move water and nutrients, so they

cannot grow to be more than a few centimeters thick.

Non-Vascular Plants Cont… Need moisture to reproduce…they can live on land

but must live in a place where there is moisture. During reproduction…they undergo alternation of

generations First stage is the gametophyte stage (the cells in this

phase are haploid (n) Second stage is the sporophyte stage (diploid cells (2n)

undergo to meiosis in order to produce haploid (n) spores These spores then germinate and undergo the gametophyte stage

again.

Mosses The most well known non-vascular plant Can live where there is very little soil Many mosses can tolerate low temperatures Resistant to most diseases and pollutants Considered a ‘pest’ by some people. Mosses also have a “stem-like” structure

Vascular Plants Called a tracheophyte Has vascular tissues that transport water and

nutrients throughout the body Two types of vascular tissue:

Xylem – carries water and minerals from the roots of the plant up through to the rest of the plant

Phloem – carries the food molecules from the leaves (where the food is made during photosynthesis) to wherever food is needed in the plant.

If something harms the vascular tissue of a plant it can die from lack of water and nutrients

Seedless Vascular Plants Have vascular tissue for transport Do not produce flowers Do not produce seeds for reproduction…

instead the reproduce by using sporesspores.. Most seedless vascular plants are found in

warm moist regions of the world

4 Divisions of Seedless Vascular Plants

Division Psilotophyta (includes Whisk ferns – very simple plants with no roots or true leaves)

Division Lycophyta (includes club mosses…look similar to bryophyte mosses but have true roots, leaves, and stems) The spores from club mosses was used to make the flash for

photograghers before electronic flashes were invented) Division Sphenophyta (includes a group of plants called horsetails

which used to be used to scrub pots and pans because they had a lot of silica in their stems) Only one genus of Sphenophyta is not extinct today: genus Equisetum…

for this reason, they are considered “living fossils” Division Pterophyta (the ferns)

This is the 2nd largest division in the Plant Kingdom…and probably the most familiar

Characteristics and Structure of a Fern Have true roots and leaves Very thick underground stems called rhizomes. The leaves are called fronds Produce thousands of spores each year.

The spores are stored in brownish colored spore cases called sporangia…the sporangia are found on the underside of the of a frond

The roots and the fronds grow from nodes on the rhizomes Need moisture for reproduction The young leaves (called “fiddleheads”) are a delicacy for

many animals

Fern Reproduction Do not produce flowers or seeds Use of spores and need of water for reproduction is similar to mosses Like all other plants, undergo alternation of generation…have a life cycle

similar to that of a moss, but in ferns, the sporophyte is the dominant phase (Nonvascular plants are the only ones that have a dominant gametophyte

phase) Steps of reproduction:

Diploid (2N) sporophyte produces haploid (n) spores by meiosis The spores grow into the gametophyte (n) The gametophyte produces gametes (sprem and egg cells) through the

process of meiosis When there is water present…a sperm cell can fertilize an egg cell The fertilized cell then grows into another sporophyte and the cycle begins

again.

Vascular Seed- producing Plants Seeds are produced instead of spores…the use

of seeds for reproduction eliminates the need for water because pollen that contains a sperm cell can travel by water, wind, or other means in order to fertilize an egg cell

Vascular Seed Plants are divided into Gymnosperms Angiosperms

Gymnosperms Produce seeds but do NOT produce flowers “Gymnosperm” literally means “naked

seed”…the gymnosperms get this name because they do not enclose the seed in fruit.

Some produce seeds in cones (but not all)

The 4 Divisions of the Vascular Seed Plants Division Cyadophyta – The Cycads Division Ginkophyta – only one species in this

division can be found living today (Ginko biloba) Division Gnetophyta – can be woody vines, small

shrubs, or even turnip-like plants Division Coniferophyta – The conifers…plants that

produce seeds in cones. This division also includes the tallest trees: the Redwoods

Division Coniferophyta Over 500 known species. Includes pine trees, cedars, redwoods,

spruces, and firs. Have either scale-like or needle-like leaves,

and many species are considered “evergreen” since they remain green all year.

Reproduction and Life Cycle of Conifers Reproduce by producing seeds in cones Alternation of generation with the dominate phase being the

sporophyte phase. The gametophyte of a conifer is VERY small and is actually

contained in the sporophyte tissues. Conifers such as pine trees produce two types of cones.

One smaller pollen cone that produces pollen grains that contain the male gametes or sperm cells

The larger cones contain the female gametes, or egg cells In the spring, the pollen cones release huge amounts of

pollen…some of which gets caught on the sticky material found inside the seed cone

The scales of the seed cone help to protect the seed,

Angiosperms Often called “The Flowering Plants” because all angiosperms have

reproductive structures called flowers. Flowers serve a number of functions:

Attract insects that will help pollinate the plant Contain a part called an ovary which develops into a fruit that protects the

seed. Pollination processes in angiosperms is much more efficient than in

gymnosperms. The term ‘angiosperm’ literally means “closed seed”. The fruit of angiosperms serves as a food source for many organisms. Divided into two major categories:

Monocots Dicots

Seed Structure and Function Each seed from an angiosperm has three main parts:

The seed coat The embryo (or immature plant) The stored food

The leaf part of the seed embryo is called a cotyledon (or seed leaf)…and often becomes the first leaf of the new plant once it sprouts

Monocots have one cotyledon Dicots have two cotyledons

Other Differences in Monocots and Dicots Monocots have parallel leaf veination Dicots have branched veination in their leaves

Monocots have fibrous roots Dicots have a main tap root

The following diagrams and pictures should summarize almost all of the differences between monocots and dicots

Reproduction in Angiosperms The pistil is the female part of a flower and consists of the stigma, style,

ovary, and ovule Stigma – part of the female reproductive structure; has a sticky substance that

helps the pollen grain to adhere. Style – tube that connects the stigma with the ovary Ovary – contains and protects the female gamete; becomes the fruit once

fertilization has occurred. Ovule – contains the female gamete or egg; becomes the seed once it has

been fertilized. The stamen is the male part of a flower and contains the anther and the

filament Anther – male reproductive structure of a flower that produces the pollen. Filament – part of the male reproductive structure in a flower; “the stalk” that

supports the anther.

Flower Structure Continued Sepals – the green parts that cover the bud of the flower

before it blooms…NOT directly involved in reproduction. Petals – meant to attract insects and other animals that can

help to pollinate the flower ***Flowers with both male and female reproductive

structures are called Perfect Flowers. Flowers that only contain one reproductive structure (either male or female) are called Imperfect Flowers.

***If a flower has all four main parts (pistil, stamen, petals, and sepal) it is said to be a complete flower. If it does not have all four of these parts, it is an incomplete flower

Pollination and Fertilization Pollination is the transfer of pollen to the

female part of the flower. Methods of pollination include:

Wind Insects and other animals Water

Pollination and Fertilization The anther splits open to expose mature pollen grains. The pollen is picked up by one of the pollinating agents. While the pollen has been maturing, the egg cells have also been

maturing in preparation for pollination and fertilization. The stigma at the top of the pistil becomes “receptive”…so pollen can

stick to it. When the correct type of pollen sticks to the stigma, the pollen will form

a pollen tube which travels down to the ovary from the pistil. The pollen releases two sperm cells near the mature egg cell Fertilization occurs when one of these pollen cells joins with the egg

cell. Once fertilization has occurred, the result is the formation of a zygote The zygote develops into the embryo found in the seed.