Kingdom Plantae: Types of Plants and Their Characteristics
I. Background Information and Characteristics
A. Basic Characteristics of All Plants
1. Many-celled, eukaryotic organisms.
2. Contain the pigment chlorophyll for photosynthesis.
3. Each cell is surrounded by a cell wall (made of cellulose) that gives the entire plant support as well as
helps keep them from drying out.
4. Most are anchored to the ground with roots or rootlike structures.
5. Plants that live on land have a waxy layer (called the cuticle) covering their leaves to prevent water
from being lost to the air.
a. Without a cuticle, the leaves would lose the water before it can be used to make food in
photosynthesis.
b. The job of the cuticle is to keep water inside the leaf—not to prevent water from getting in to the
leaf from the outside.
B. Vascular vs. Nonvascular
1. vascular plants = plants that have tubelike tissues that transport materials throughout the plant.
a. xylem = tubular tissue that transports water and minerals from the roots throughout the entire plant.
1. Getting water to the leaves is especially important for food production (photosynthesis).
b. phloem = tubular tissue that transports food (glucose) made in the leaves to the rest of the plant.
1. The food may be used immediately by the cells or it may be stored for later use.
c. cambium = a layer of growth tissue between the xylem and phloem.
1. The cambium is responsible for producing new xylem and phloem cells.
2. nonvascular = plants that do not have tubelike tissues to transport materials.
a. Nonvascular plants rely on diffusion to transport water, minerals, and food throughout the plant.
1. These plants cannot grow very tall since they have no transportation tubes.
II. Seedless Plants
A. Mosses—An Example of Nonvascular, Seedless Plants
1. Mosses are made up of leaflike structures growing around a stalk and are anchored to the ground with
rootlike structures called rhizoids.
2. Mosses reproduce by alternating asexual and sexual stages— this is know as alternation of
generations.
a. During the asexual stage, a sporophyte plant grows and produces spores.
b. If the spores land in a moist environment, they will develop into gametophyte plants (sexual stage).
1. The male gametophyte will produce sperm, the male sex cell (sex cells are called gametes).
2. The female gametophyte will produce eggs, the female gamete.
c. When moisture is present, the sperm will be released and swim to the egg, fertilizing it (this means
that the haploid gametes combine to form a diploid fertilized egg called a zygote).
d. The zygote will grow (by mitosis) and develop into the sporophyte plant— the cycle starts over.
B. Ferns—An Example of Vascular, Seedless Plants
1. The part of the fern plant that we usually see is the feathery leaf called the frond, which grows from an
underground stem called the rhizome.
a. Roots grow from the rhizome to anchor the fern and to absorb water and minerals from the soil.
2. Ferns also have an alternation of generations when they reproduce.
a. The frond is the sporophyte generation, producing spores in spores cases (called sori) on the
underside of the leaf.
b. A spore landing in a moist area will develop into small heart-shaped gametophyte plant called
a prothallus, which produces both sperm and eggs— these meet and fertilize to form a zygote.
b. The zygote then develops into the sporophyte (the frond), and the cycle repeats itself.
3. Since ferns are vascular and can transport water and food, they can grow to be very tall.
a. The fossil fuel deposits used today formed from ferns and other plant material that collected in
swamps and were buried by sediment, changing over time into coal, petroleum, and natural gas.
III. Seed Plants— Their Structure and Functions
A. Parts of Complex Seed Plants
1. Roots
a. Roots have 2 major jobs:
1. to absorb water and dissolved minerals from the soil and transport them through the xylem (they
are “true roots” since they contain vascular tissue).
2. to anchor the plant in the ground so they are not knocked over by wind or water.
a. Roots also help prevent soil erosion by holding the soil in place so it is not blown or washed
away.
b. In some plants, food is stored in the roots if it is not needed right away (ex. carrots, beets, radishes).
2. Stems
a. Stems support the plant’s leaves so they can compete for sunlight and the flowers so they can be
pollinated for reproduction.
1. Some stems can store water (ex. cactus) and some store food (ex. potatoes and onions— examples
of underground stems).
b. Stems come in 2 types:
1. herbaceous stems = soft, green, flexible stems found in plants that complete their life cycle in one
growing season (they grow from a seed, produce new seeds, and die).
a. Since they only live one year (they are called annuals), they do not need a cambium layer
because they do not need to grow new xylem and phloem for the next year.
2. woody stems = strong, rigid stems containing a large amount of xylem tissue.
a. Each year, the cambium grows a new set of xylem and phloem cells in woody plants.
b. The new layer of cells wraps around last year’s layer, producing the annual rings found in
woody stems, such as trees.
1. By looking at the size and shape of the rings, scientists can find important climate data.
c. Woody plants that grow for more than 2 years are called perennials, while those that grow for
only 2 growing seasons are called biennials.
3. Leaves
a. Leaves consist of 2 parts—the stalk (connects the leaf to the stem) and the blade (the thin, flat part).
1. Leaves that have only one blade are called simple leaves, while those made up of 2 or more blades
are called compound leaves.
b. Leaves are responsible for carrying out photosynthesis by capturing the sun’s energy in the
chloroplasts and using it to combine water (from the soil) and carbon dioxide (from the air) to form
glucose— the food for the plant.
c. The structures that make up the leaf are designed for this photosynthetic process.
1. upper epidermis = a thin, protective layer of cells (the cells do not contain chlorophyll so that the
light may pass directly through them to the palisade layer).
a. This layer is covered by the cuticle to prevent the loss of water.
2. palisade cells = long, rectangular cells packed tightly together under the upper epidermis; these
cells trap sunlight in their chloroplasts to produce food through photosynthesis.
3. spongy cells = irregularly-shaped cells that are loosely packed together, creating air spaces; these
cells also trap light and produce food.
4. air spaces = spaces in the spongy layer that provide room for the carbon dioxide to enter the leaf
and allow it and the water to come in contact with the cells; they also provide room for the
oxygen and water vapor (created as waste products during photosynthesis) to exit the cell through
the stomata.
5. lower epidermis = same structure and function as the upper epidermis; found on the underside of
the leaf (also covered by a cuticle).
6. vascular tissue = the xylem and phloem cells that make up the veins in the leaf; this tissue is
responsible for delivering the water needed for photosynthesis and for transporting the newly
formed food to the rest of the plant.
7.
stoma (plural: stomata) = a small opening or pore on the underside of the leaf; carbon dioxide
enters the leaf through the stomata and oxygen and water vapor exit through them; stomata are
usually open during the day (when photosynthesis occurs) and closed at night (to conserve water).
a. transpiration = the process by which water is lost through the stomata; more water is lost
through transpiration than is used during photosynthesis (ex. an apple tree can lose as much as
15 liters of water per hour on a hot, sunny day).
b. Plants in desert environments have fewer stomata than plants in climates that get more rainfall.
8. guard cells = a pair of cells surrounding each stoma; they open and close to control the amount of
water lost by the leaf.
B. Types of Complex Seed Plants and Their Process of Reproduction
1. Gymnosperms are woody-stemmed, vascular plants that produce seeds on the scales of female cones.
a. The seeds are not protected by fruit—they are “naked” (gymnosperm in Greek means “naked seed”).
b. The leaves of most gymnosperms are needle-like and stay on the tree year round— they are
evergreen (they do lose their leaves, but they fall off a few at a time and are quickly replaced).
c. There are 4 divisions of gymnosperms, the largest and most familiar being the conifers.
d. Reproduction in Conifers
1. Male cones form at the top of the tree and produce pollen (which contains sperm and other
specialized cells).
2. Female cone (usually found lower on the tree) produce eggs (ovules) on the bottom of the scales
of the cone.
3. The pollen is released by the male cones in a cloud and is carried by the wind and/or gravity (most
of the pollen never reaches the female cones— it is blown away).
4. If a pollen grain lands on the top of the scale of the female cone (of the same species), the
specialized cells in the pollen grain will grow a pollen tube down to the ovule so the sperm can
swim down it and fertilize the egg, forming a zygote.
a. If a pollen grain lands on the cone of a different species, the pollen tube will not form and
fertilization will not take place.
5. An embryo (the tiny plant found inside the seed) will develop from the zygote.
6. Once the seeds are formed in the female cone, the scales open up and the cone releases the seeds.
a. The seeds usually have a “wing” on them to help them be carried away from the parent plant
(animals may take and bury the seeds, helping to distribute them).
2. Angiosperms are flowering, vascular plants that produce seeds that are surrounded by fruit (they are
currently the dominant group in the plant kingdom).
a. Angiosperms are divided into 2 classes: monocotyledons (monocots) and dicotyledons (dicots).
1. cotyledon = the part of the seed that is stored food to provided energy for the tiny plant (embryo);
it is also called a seed leaf.
b. Monocots versus Dicots
1. Monocot Characteristics (examples of monocots: corn, rice, oats, wheat, grass)
a. have only 1 seed leaf (one cotyledon).
b. xylem and phloem are in bundles and are scattered throughout the stem.
c. the veins in the leaves are parallel.
d. the parts of a monocot flower are in multiples of 3.
2. Dicot Characteristics (examples of dicots: trees, lettuce, beans, watermelon, pumpkins)
a. have 2 seed leaves (two cotyledons).
b. xylem and phloem are in a ring pattern in the stem.
c. the veins in the leaves are branched.
d. the parts of a dicot flower are in multiples of 4 or 5.
c. Reproduction in Angiosperms
1. Angiosperms use flowers to reproduce and form seeds (flowers contain the reproductive organs).
2. Parts of a Flower
a. Male Parts
1. The male organs in a flower are the stamen, which are made up of 2 parts:
a. anther = tip of the stamen that produces pollen grains.
1. pollen grains = contain the sperm and special cells that will form the pollen tube.
b. filament = a slender stalk that holds up the anther.
b. Female Parts
1. The female organ in a flower is the pistil, which is made up of 3 parts:
a. stigma = the top of the pistil that is covered with a sticky substance.
1. The stickiness helps collect and hold the pollen grains.
2. The stigma also produces nectar (a sugary fluid) to attract insects and animals.
b. style = a long stalk through which the pollen tube grows.
c. ovary = located at the base of the pistil; produces and stores the ovules (egg cells).
c. petals = colorful structures that help attract insects and animals which are important for the
pollination (in flowers that use the wind for pollination, petals are often small and dull in color).
d. sepals = green, leafy structures that surround and protect the flower’s parts before the blossom
opens.
3. Pollination, Fertilization, and Seeds
a. pollination = the transfer of pollen from the anther to a stigma (insects and animals often help
in this process by carrying pollen from flower to flower).
1. Self-pollination occurs when pollen from Flower A land on the stigma of Flower A (the
flower pollinates itself).
2. Cross-pollination occurs when pollen from Flower A lands on the stigma of Flower B (one
flower pollinates another flower).
a. Cross-pollination strengthens the species because the hereditary material is shared and the
strong characteristics tend to come out in the offspring.
b. Fertilization occurs when the pollen grain on the stigma grows a pollen tube down through the
style, into the ovary, and attaches to the ovule.
1. The sperm in the pollen grain swims down the tube and unites with the ovule, combining its
chromosomes with the egg’s chromosomes (it is now a diploid fertilized egg or zygote).
2. After fertilization, each zygote develops into a seed and the ovary ripens into a fruit.
a. fruit = the ripened ovary tissue that surrounds and protects the seeds; fruits may be fleshy
(like an apple or tomato) or dry and hard (like an almond or walnut); fleshy fruits provide
moisture and nutrients for the young plant when it first sprouts (germinates).
c. Seeds are made up of 3 parts:
1. seed coat = hard, protective covering surrounding the seed; develops from the ovule’s wall.
2. embryo = the tiny plant inside the seed.
3. cotyledon = the seed leaf that stores food (in the form of starch) for the embryo.
a. Seeds can have 1 cotyledon (monocot) or 2 cotyledons (dicot).
d. seeds dispersal = the means by which the seeds are moved away from the parent plant; the
seeds may have specialized structures (such as “wings” or “hooks”) to help them do this.
1. Seeds can be carried away from the parent plant by:
a. the wind.
b. attaching to an animal’s fur.
c. animals taking the seed to eat or bury.
d. water currents.
e. animals eating the fruit and dropping seeds in their waste.
4. Seed Germination
a. germination = the early growth or sprouting of the plant from the seed; when the embryo
grows and “pops” out of the seed.
b. To germinate, the seed must have the proper temperature and the proper amount of moisture
and oxygen.
1. The moisture helps soften the seed coat so the embryo can pop out.