WHAT IS A PLANT?

PLANT ADAPTATIONS FOR LAND

• Most plants live on land.
• For plants to survive on land, they must obtain,
• Water and nutrients from their surroundings,
• Retain water,
• Transport materials in their bodies, and reproduce.

NONVASCULAR PLANTS

• There are three major groups of nonvascular plants: mosses, liverworts, and hornworts.
• These low-growing plants live in moist areas.
• They live there so they can absorb water and other nutrients from the environment.
• The watery surroundings also enable sperm cells to swim to egg cells

MOSSES

• With more than 10,000 species, mosses are the most diverse group of nonvascular plants.
• They grow on sidewalk cracks, tree trunks, and in other damp, shady spots.
• The familiar green, fuzzy moss is the gametophyte generation plant.
• Structures that look like tiny leaves grow off a small, stemlike structure.
• The sporophyte generation grows out of the gametophyte.

LIVERWORTS

• There are more than 8,000 species of liverworts.
• They are often found growing as a thick crust on moist rocks or soil along the sides of a stream.
• It gets its name from the shape of of the plant's leaflike gametophyte, that looks like a human liver.
• Wort is an old English word for "plant."
• Liverworts have sporophytes that are too small to see.

HORNWORTS

• There are fewer than 100 species of hornworts.
• Unlike mosses and liverworts, hornworts are seldom found on rocks or tree trunks.
• Instead, hornworts usually live in moist soil, often mixed in with grass plants.
• Named from the slender, curved structures that grow out of the gametophytes.
• These hornlike structures are the sporophytes.

SEEDLESS VASCULAR PLANTS

• Are the ancestors of ferns, horsetails, and club mosses.
• They are seedless plants that have vascular tissue.

FERNS

• There are more than 12.000 species of ferns alive today.
• They have true stems, roots, and leaves.
• The stems of ferns are mostly underground.
• The leaves, or fronds, are divided into many smaller parts that look like small leaves.
• Fern gametophytes are tiny plants that grow low to the ground.

HORSETAILS

• There are very few species of horsetails on Earth today.
• The stems of horsetails are jointed.
• Long, coarse, needle-like branches grow in a circle around each joint.
• Another name for horsetails is scouring rushes.

CLUB MOSSES

• They have true stem, roots, and leaves.
• There are only a few hundred species alive today.
• Unlike true mosses, club mosses have vascular tissue.
• The plant is sometimes called ground pine or princess pine.
• Club mosses usually grow in moist woodlands and near streams.

SEED PLANTS

• Seed plants produce much of the oxygen you breathe.
• They have vascular tissue.
• They use pollen and seeds to reproduce.
• All of them have roots, stems, and leaves.
• The gametophyte are microscopic.

VASCULAR TISSUE: PHLOEM/XYLEM

• There are two types of vascular tissue, phloem and xylem.
• Phloem is the vascular tissue through which food moves.
• When the food is made into leaves, it enters the phloem and travels to other parts of the plant.
• Water and minerals, on the other hand, travel in the vascular tissue called xylem.
• The roots absorb water and minerals from the soil. The minerals enter the root's xylem and move upwards.

POLLEN AND SEEDS

• They can live in a wide variety of environments.
• Seed plants produce pollen, tiny structures that contain the cells that will become sperm cells.
• Pollen delivers sperm cells directly near the eggs. After sperm cells fertilize the eggs, seeds develop.
• A seed is a structure that contains a young plant inside a protective covering.
• Seeds protect the young plant from drying out.

SEED STRUCTURE

• A seed has three main parts—an embryo, stored food, and a seed coat.
• The young plant that develops from the zygote, or fertilized egg, is called the embryo.
• In some seeds, food is stored in the cotyledons.
• The outer covering of a seed is called a seed coat. It protects the embryo and it's food from drying out.

SEED DISPERSAL

• The scattering of seeds is called dispersal.
• Seeds are dispersed in many ways.
• One method involves other organisms.
• A second is water.
• And another is wind.

GERMINATION

• Germination occurs when the embryo begins to grow again and pushes out of the seed.
• Germination begins when the seed absorbs water from the environment.
• Then the embryo uses its stored food to begin to grow.

ROOTS

• Roots have three main functions,
• Roots anchor a plant in the ground,
• Absorb water and minerals from the soil,
• And sometimes store food.
• The root cap protects the root from injury from rocks as the root grows through the soil.

STEMS

• The stem of a plant has two main functions,
• The stem carries substances between the plant's roots and leaves.
• It also provides support for the plant and holds up the leaves so they are exposed to the sun.
• Some stems store food.
• Stems can be either herbaceous or woody.

LEAVES

• Leaves vary greatly in size and shape.
• Leaves capture the sun's energy and carry out the food-making process of photosynthesis.
• The leaf's top and bottom layers protect the cells inside.
• Between the layers of cells are veins that contain xylem and phloem.

GYMNOSPERM

• A gymnosperm is a seed plant that produces naked seeds.
• In addition, many gymnosperms have needle-like or scale like leaves.
• And they also deep-growing root systems.
• Gymnosperms are the oldest type of seed plant.

EXAMPLES OF GYMNOSPERMS

• Some examples of gymnosperms are cycads, conifers, ginkgoes, and gnetophytes.
• Cycads look like palm trees with cones.
• Conifers are the largest and diverse group of gymnosperms.
• Only one species of ginkgoes exists today.
• Gnetophytes live in hot deserts and in tropical rain forests.

ANGIOSPERMS

• Rafflesia belongs to the group of seed plants known as angiosperms
• All angiosperms share two traits,
• First, they produce flowers,
• Second, angiosperms produce seeds that are enclosed in fruits.
• Angiosperms live in almost everywhere on Earth.

EXAMPLES OF ANGIOSPERMS

• Examples of angiosperms are pollination, fertilization, fruit development and seed dispersal.
• A flower is pollinated when a grain of pollen falls on the stigma.
• If the pollen falls on the stigma of a similar plant, fertilization can occur.
• After fertilization, the ovary changes into a fruit.
• Fruits are the means by which angiosperms seeds dispersed.

MONOCOTS VS DICOTS

• Grasses, including corn, wheat, and rice, and some plants are monocots.
• The flowers of a monocot usually have either three petals or a multiple of three petals.
• Dicots include plants such as roses and violets, as well as dandelions.
• The flowers of dicots often have either four or five petals or multiples of the numbers.

PLANT TROPISMS: TOUCH, LIGHT, GRAVITY

• A plant's growth response toward or away from a stimulus is called a tropism.
• Some plants, such as bladderworts, show a response to touch called thigmotropism.
• All plants exhibit a response to light called phototropism.
• Plants also respond to gravity called gravitropism.