What is a Plant? with Plant Diversity

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What is a Plant? with Plant Diversity

• Chapter 21 22

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What is a plant?

• Multicellular eukaryote
• Produce their own food through photosynthesis
• Have thick cell walls made of cellulose

• Stems leaves of most have a waxy waterproof
  coating called a cuticle

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Origins of Plants

• Scientists hypothesize that all plants probably
  evolved from filamentous green algae that lived
  in the ancient oceans
• Some of the evidence for their relationship can
  be found in modern members of both groups

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Comparing Plants to Algae

• Green algae and plants have cell walls that
  contain cellulose
• 2. Both groups have the same types of chlorophyll
  used in photosynthesis and store food in the form
  of starch.

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The 1st plants

• The first evidence of plants in the fossil record
  began to appear over 440 million years ago
• These early plants were simple in structure and
  did not have leaves.
• They were probably instrumental in turning bare
  rock into rich soil

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Adaptations of Plants

• Preventing water loss Most fruits, leaves, and
  stems are covered with a protective, waxy layer
  called the cuticle
• The waxy cuticle creates a barrier that helps
  prevent the water in the plants tissues from
  evaporating into the atmosphere

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Adaptations of Plants

• 2. Carrying out photosynthesis The leaf, is a
  plant organ that grows from a stem and usually is
  where photosynthesis occurs
• Each plant species has unique leaves or leaflike
  structures

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Adaptations of Plants

• 3. Putting down roots Plants can take in water
  and nutrients from the soil with their roots
• In most plants, a root is a plant organ that
  absorbs water and minerals usually from the soil

• Roots anchor a plant usually in the ground
  function as storage.

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Adaptations of Plants

• Transporting materials Water moves from the
  roots of a tree to its leaves, and the sugars
  produced in the leaves move to the roots through
  the stem
• A stem is a plant organ that provides support for
  growth.

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Transporting Materials

• It contains tissues for transporting food, water,
  and other materials from one part of the plant to
  another
• Stems also can serve as organs for food storage
• In green stems, some cells contain chlorophyll
  and can carry out photosynthesis.

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Xylem Pholem
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Xylem Pholem

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Transporting materials
Phloem
Xylem
Xylem transports water and dissolved substances
other than sugar throughout the plant.
Phloem transports dissolved sugar throughout the
plant.
Cambium
Cambium produces xylem and phloem as the plant
grows.
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Nonvascular Plants

• Nonvascular plants do not have the conducting
  tissues xylem and phloem Examples mosses,
  liverworts hornworts

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Nonvascular Plants
Moss
No true roots, stems, or leaves, must live near
water or moist environment
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Vascular Plants

• Vascular plants have tubes and vessels to
  transport water and nutrients (Xylem Phloem)
  Grass, trees, flowers, ferns
• Vascular plants can live farther away from water
  than nonvascular plants.

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Vascular Plant are divided into

• Seed Plants-flowers, pines, trees, grasses
• subdivided into
• angiosperms-flowering plants
• gymnosperms-cone bearing plants
• Seedless plants-ferns

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Vascular Plants

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Vascular Nonvascular Plants
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Reproductive Strategies (1)

• A seed is a plant organ that contains an embryo,
  along with a food supply, and is covered by a
  protective coat.
• It also protects the embryo from drying out and
  also can aid in its dispersal

Embryo
Seed Coat
Food Supply
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Reproductive Strategies (2)

• In non-seeded plants (mosses ferns) the sperm
  requires a film of water on the gametophytes
  plant to reach the egg

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Reproductive Strategies (3)

• In seed plants, which include all conifers and
  flowering plants, sperm reach the egg without
  using a film of water
• This difference is one reason why non-seed plants
  require wetter habitats than most seed plants

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Spores

• In non-seed vascular plants such as ferns, spores
  have hard outer coverings
• Spores are released directly into the environment
  where they can grow into haploid gametophyte
  plants
• These plants produce male and female gametes

• Following fertilization, the sporophyte plant
  develops and grows on the gametophyte plant.

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Seeds

• In seed plants, such as conifers and flowering
  plants, spores develop inside the sporophyte and
  become the gametophytes.
• The gameotophytes consist of only a few cells
• Male and female gametes are produced by these
  gametophytes

• After fertilization, a new sporophyte develops
  within a seed. The seed eventually is released
  and the new sporophyte plant grows.

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Non seeded Plants
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Non-seed Plants

• Non-seed plants include vascular or nonvascular
  organisms.

• Non-seed plants are either vascular
• Or non-vascular

• There are 7 divisions of
• Non-seeded plants. These
• Plants produce hard-walled
• Reproductive cells called
• Spores

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Hepaticophyta Liverworts

• Small plants commonly called liverworts because
  the flattened body of the plant and it resembles
  the lobes of an animals liver
• They grow in moist environments
• They use osmosis diffusion to transport water
• Found from Artic to Antarctic
• Some found in water, others in deserts

• Most have an oily/shiny surface

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2 kinds of liverworts

• Thallose liverwort
• have broad body that looks like a lobed leaf

• The body of a thallose liverwort is called a
  thallus.
• Found growing on damp soil

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2 kinds of liverworts

• 2. Leafy Liverwort are creeping plants with 3
  rows of thin leaves attached to a stem

• Leafy liverworts grow close to the ground and
  usually are common in tropical jungles and areas
  with persistent fog
• Their stems have flat, thin leaves arranged in
  three rowsa row along each side of the stem and
  a row of smaller leaves on the stems lower
  surface

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Anthocerophyta Hornwort

• Small Plants
• Sporophytes resembles the horns of an animal
• Nonvascular plant-grows in damp, shady habitats
• Relies on osmosis diffusion to transport
  nutrients

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Hornworts

• Are the smallest division of nonvascular plants
• Currently consisting of only about 100 species
• are similar to liverworts in several respects

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Bryophyta Mosses

• Nonvascular plants
• Rely on osmosis and diffusion to transport
  materials
• Habitats include close to streams, rivers or
  humid tropical forest
• Limited in size (less than 5 cm tall)
• Cannot compete with vascular plants

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Mosses

• Mosses
• More familiar than liverworts
• Small plant w/ leafy stems
• Grow in dense carpets or turfs
• Mosses have rhizoids, which help anchor the stem
  to the soil.

• Some have upright stems others have creeping
  stems that lie along the ground or hang from
  steep banks or tree branches

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Mosses

• Some mosses form extensive mats that help retard
  erosion on exposed rocky slopes
• Moses grow in a wide variety of habitats, even in
  the arctic during the brief growing season where
  sufficient moisture is present
• A well-known moss is Sphagnum, also known as peat
  moss.
• This plant thrives in acidic bogs in northern
  regions of the world. It is harvested for use as
  fuel and is a commonly used soil additive

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Psilophyta Wisk Ferns

• Consist of thin, green stems.
• Are unique vascular plants because they have
  neither roots nor leaves
• Small scales that are flat, rigid, overlapping
  structures cover each stem.

• The two known genera of psilophytes are tropical
  or subtropical, only 1 found in U.S.

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Lycophyta Club Mosses

• Vascular plants adapted primarily to moist
  environments
• Have stems, roots, and leaves
• Their leaves, although very small, contain
  vascular tissue
• Ancestors grew as tall as 30 m and formed a large
  part of the vegetation of Paleozoic forests

• The plants of these ancient forests have become
  part of the coal that is now used by people for
  fuel.

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Club Moss

• The club moss, Lycopodium, is commonly called
  ground pine because it is evergreen and resembles
  a miniature pine tree
• Some species of ground pine have been collected
  for decorative uses in such numbers that the
  plants have become endangered

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Arthrophyta Horsetails

• Vascular plants
• They have hollow, jointed stems surrounded by
  whorls of scalelike leaves
• The cells covering the stems contain large
  deposits of silica
• About 15 species of arthrophytes exist today

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Horsetail

• Early horsetails were tree-sized members of the
  forest community. Todays arthrophytes are much
  smaller than their ancestors
• There are only about 15 species in existence, all
  of the genus Equisetum
• These plants also are called scouring rushes
  because they contain silica, an abrasive
  substance
• Most horsetails are found in marshes, in shallow
  ponds, on stream banks, and other areas with damp
  soil

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Pterophyta Ferns

• The most well-known and diverse group of non-seed
  vascular plants.
• They have leaves called fronds that vary in
  length from 1 cm to 500 cm
• The large size of fronds is one difference
  between pterophytes and other groups of seedless
  vascular plants

Although ferns are found nearly everywhere, most
grow in the tropics
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Ferns

• According to fossil records, fernsdivision
  Pterophytafirst appeared nearly 375 million
  years ago
• Ancient ferns grew tall and treelike and formed
  vast forests

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Fern Structures

• In most ferns, the main stem is underground.
  This thick, underground stem is called a rhizome.

Fronds
Rhizome
Root
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Fern Structures

• The leaves of a fern are called fronds and grow
  upward from the rhizome.

• The fronds are often divided into leaflets called
  pinnae, which are attached to a central rachis.

• The branched veins in ferns transport water and
  food to and from all the cells.
• Fern spores are produced in structures called
  sporangia

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Sorus

• Clusters of sporangia form a structure called a
  sorus (plural, sori). Sori are usually found on
  the underside of fronds but in some ferns, spores
  are borne on modified fronds

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Seeded Plants
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Cycadophyta Cycads

• Were abundant during the Mesozoic Era.
• Today, there are about 100 species of cycads
• They are palmlike trees with scaly trunks and can
  be short or more than 20 m in height
• Cycads produce male and female cones on separate
  trees

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Cones

• Cones are woody strobili scaly structures that
  support male or female reproductive structures
• Seeds are produced in female cones.
• Male cones produce clouds of pollen

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Diversity of Cone Bearing Trees

• Trees that bear cones are called gymnosperms
• Characteristics
• produce seeds in cones (pines, firs, cedars)
• needle-like leaves

Male cones produce pollen
Female cones contain seeds
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Adaptations in Coniferophyta

• The reproductive structures of most conifers are
  produced in cones.

Wing
Wing
Pollen grain
Two seeds
Spores
Ovule
Pollen sac
Male cones
Female cone
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• Evergreen confiers trees that are green year
  round photosynthesize when conditions are right
• Deciduous trees lose their leaves each fall to
  conserve water through winter conditions

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Gnetophyta Gnetophytes

• There are three genera of gnetophytes (NEE toh
  fites) and each has distinct characteristics
• 1. Gnetum (Nee tum) includes about 30 species of
  tropical trees and climbing vines

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Gnetophyta Gnetophytes

• There are about 35 Ephedra (eh FEH dra) species
  that grow as shrubby plants in desert and arid
  regions

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Gnetophyta Gnetophytes

• Welwitschia (wel WITCH ee uh) has only one
  species, which is found in the deserts of
  southwest Africa
• Its leaves grow from the base of a short stem
  that resembles a large, shallow cap

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Ginkogophyta Ginko biloba

• This division has only one living species, Ginkgo
  biloba, a distinctive tree with small, fan-shaped
  leaves
• All ginkgoes are cultivated trees, and they are
  not known to exist in the wild

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Ginkos

• Ginkgoes (GING kohs) have male and female
  reproductive structures on separate trees.
• The seeds produced on female trees have an
  unpleasant smell, so ginkgoes planted in city
  parks are usually male trees
• Ginkgoes are hardy and resistant to insects and
  to air pollution

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Coniferophyta Cone-Bearing Trees

• These are the conifers (KAH nuh furz),
  cone-bearing trees such as pine, fir, cypress,
  and redwood
• vascular seed plants that produce seeds in cones

• Species of conifers can be identified by the
  characteristics of their cones or leaves that are
  needlelike or scaly.

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Bristlecone Pine

• Bristlecone pines, the oldest known living trees
  in the world, are members of this plant division.

• Another type of conifer, the Pacific yew, is a
  source of cancer-fighting drugs.

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Anthophyta The Flowering Plants

• Commonly called the flowering plants, are the
  largest, most diverse group of seed plants living
  on Earth
• There are approximately 250 000 species
• Unlike conifers, anthophytes produce flowers from
  which fruits develop

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Diversity of flowering plants

• Flowering plants, also called angiosperms,
  produce seeds enclosed within a fruit.
• A fruit includes the ripened ovary of a flower.

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Anthophyta

• A fruit usually contains one or more seeds.
• Division has 2 classes

• Monocotyledons (mah nuh kah tul EE dunz) include
  grasses, orchids, lilies, and palms

• Dicotyledons (di kah tul EE dunz).

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Monocot Characteristics
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Dicot Characteristics
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Cotyledons

• An embryo is an early stage of development of an
  organism
• Embryos of seed plants include one or more
  cotyledons
• Cotyledons usually store or absorb food for the
  developing embryo.

Cotyledon
Cotyledons
Seed coat
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Parts of the Flower

• Male Stamen
• Parts Anther Filament
• Female Pistol
• Parts Stigma, Style, Ovaries, Ovule

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Parts of an Angiosperm
male
female
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Life span of anthophyta

• 1. Annual plants live for only a year or less.
  They sprout from seeds, grow, reproduce, and die
  in a single growing season.

• Annuals form drought-resistant seeds that survive
  the winter.

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Life span of anthophyta

• 2. Biennial plants have life spans that last two
  years
• -1st year grow many leaves and develop a strong
  root system
• -Over the winter, the aboveground portion of the
  plant dies back, but the roots remain alive
• -2nd year food stored in the root is used to
  produce new shoots that produce flowers and seeds.

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Life span of anthophyta

• 3. Perennials live for several years, producing
  flowers and seeds periodicallyusually once each
  year
• They survive harsh conditions by dropping their
  leaves or dying back to soil level, while their
  woody stems or underground storage organs remain
  intact and dormant