Plant Diversity

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Plant Diversity
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Kingdom Plantae

• Plants are multicellular eukaryotes
• They have cell walls made of cellulose.
• Plants develop from multicellular embryos.
• They carry out photosynthesis using the green
  pigments chlorophyll a and b.
• Most plants are autotrophs, although a few are
  parasites or saprobes that live on decaying
  materials.
• Unlike most animals, plants do not have a rigidly
  set organization to their bodies.

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Plant Life Cycle

• Characterized by alternation of generations.
• T he two generations are
• the haploid (N) gametophyte.
• the diploid (2N) sporophyte.

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Reproduction

• Seed plants have evolved reproductive cycles that
  are carried out independently of water.
• Many plants also have forms of vegetative, or
  asexual, reproduction.
• The first true plants were still dependent on
  water to complete their life cycles.
• Plants that were more capable of conserving
  water, and more capable of reproducing on dry
  land evolved and became successful.

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Reproduction

• Angiosperms have unique reproductive organs known
  as flowers.
• Flowers contain ovaries, which surround and
  protect the seeds.
• The unique angiosperm fruit is another reason for
  the success of these plants.

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Overview of the Plant Kingdom

• Botanists divide the plant kingdom into four
  groups based on three important features
  water-conducting tissues, seeds, and flowers.

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Overview of the Plant Kingdom

• There are, of course, many other features by
  which plants are classified, including
  reproductive structures and body plan.

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Bryophyte Organization 

• Bryophytes have life cycles that depend on water
  for reproduction.
• Lacking vascular tissue, these plants can draw up
  water by osmosis only a few centimeters above the
  ground.

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Seedless Vascular Plants 

• The first vascular plants had a new type of cell
  that was specialized to conduct water.
• Xylem a vascular tissue that carries water
  upward from the roots to every part of a plant.
• Phloem transports solutions of nutrients and
  carbohydrates produced by photosynthesis

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Monocot and Dicot vascular system
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Plants obtain carbon dioxide for photosynthesis
from the air. Plants must balance their need to
open their stomata to receive carbon dioxide and
release oxygen with their need to close their
stomata to prevent water loss through
transpiration. the arrangement of stomata in each
is different.
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Ferns and Their Relatives

• Seedless vascular plants include club mosses,
  horsetails, and ferns.
• Ferns have survived during the Earths long
  history in numbers greater than any other group
  of spore-bearing vascular plants.
• More than 11,000 species of ferns are living
  today.

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Seed Plants 

• Seed plants are divided into two groups
  gymnosperms and angiosperms.
• Gymnosperms include the conifers, such as pines
  and spruces.
• Angiosperms include grasses, flowering trees and
  shrubs, and all wildflowers.

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Adaptation

• Adaptations that allow seed plants to reproduce
  without water include flowers or cones, the
  transfer of sperm by pollination, and the
  protection of embryos in seeds.
• Flowering plants originated on land and quickly
  came to dominate Earths plant life.
• The vast majority of living plant species
  reproduce with flowers.

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Diversity of Angiosperms

• Monocots and dicots are named for the number of
  seed leaves, or cotyledons, in the plant embryo.
  Monocots have one seed leaf, and dicots have two.

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Plant Responses 

• The responses of plants to environmental stimuli
  are called tropisms, from a Greek word that means
  turning.
• Like all living things, plants respond to changes
  in their environments.
• The response of plants to touch is called
  thigmotropism.

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Plant Responses

• Gravitropism is the tendency of a plant to grow
  in a direction in response to the force of
  gravity

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Plant Responses

• Phototropism is the tendency of a plant to grow
  toward a source of light.

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• The tree is capable of sending new roots towards
  regions rich in nutrients and severing the old
  ones, thereby actually "walking" to the food rich
  locations.

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Plant Adaptations 

• Some plants live in bogs, wet and acidic
  environments where there is very little or no
  nitrogen present.
• A number of plants that live in these habitats
  obtain nutrients using specialized leaves that
  trap and digest insects.
• Pitcher plants drown their prey in pitcher-shaped
  leaves that hold rainwater and digestive enzymes.

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Plant Adaptations 

• Carnivorous plants, such as the Venus flytrap,
  digest insectsand occasionally frogsas a source
  of nutrients.