
What is a plant? • Eukaryotic • Multicellular • Most are photosynthetic autotrophs • Some are carnivores • Some are saprophytes • Aquatic and terrestrial • Highly adapted and biochemically complex!
What kinds of growth forms are found in plants? • Aquatic • Ground cover • Herbaceous • Shrubs • Vines • Trees: midstory and canopy
Why are plants important? • Oxygen • Food • Clothing • Shelter • Medicine • Ecosystem services • Esthetic value
How are plant cells structured? • Chromosomes in a nucleus • Chloroplasts in cytoplasm • Other organelles in cytoplasm including: mitochondria, vacuoles, ribosomes, ER, Golgi bodies • Bounded by cell membrane • Outside cell membrane is cell wall
Other cell structures in plants • Stomata/stoma—openings in between plant cells in leaves for “breathing” • Guard cells—surround stomata, for opening and closing • Together these structures regulate transpiration—the process by which the water cycle flows through plant leaves
What two vital cellular processes occur in plants? • Photosynthesis—process by which light energy is chemically converted into organic compounds Carbon dioxide + water In the presence of of sunlight and chlorophyll Oxygen + Glucose
Cellular respiration • —process by which organic compounds and energy are made by all organisms Oxygen + Glucose In the presence of enzymes Carbon dioxide + water + energy (ATP)
Early plants looked very different • Some did not have distinguishable stems or leaves • Many modern plants have some similarities to ancient plants • Less complex plants have simpler structures
Stems are the most noticeable part of most plants • Stems—normally connect leaves with roots • Vascular tissue—conducting tissues in plants composed of • Xylem that has thick walled, hollow cells that carry water and minerals upward from a plant’s roots to its leaves • Phloem is made of tubes and pores that carry nutrients throughout a plant
Nonvascular and vascular plants-- • Nonvascular plants are mosses, liverworts, and hornworts • Do not need vessels because • Types of habitats-- • Division:
Nonvascular and vascular plants-- • Vascular plants have xylem and phloem, allowing them to live in many different environments other than— • Include other divisions such as--
Stems types • Herbaceous plants have soft, green stems • Woody stems have structures • Young stem has central core of pith • More mature stems have layers of xylem that form most of the wood • A cylinder of phloem is outside the xylem • Outside covered by cork
Life of wood • The layers of cork and phloem make up the bark of a tree • Wood in center is heartwood, doesn’t conduct water, gives support • Sapwood lies outside heartwood and does conduct water • Bark encloses heartwood & sapwood
Holding it all together: roots • Types: taproot and adventitious • Root hairs and root caps
What are reproductive parts of plants? • Spore • Cone • Flower • Fruit • Seed
How are plants classified? • Kingdom Plantae • Instead of being classified into PHYLA, plants are classified into DIVISIONS! • Based on structures, especially reproductive structures
Division Bryophyta app. 16,000 sp • Examples: Mosses, hornworts and liverworts • Sexual reproduction by: spores; flagellated sperm are in the antheridium and swim to the egg in the archegonium • Description: Nonvascular; small, close to the ground and to water sources; no true roots, leaves or stems; anchor with rhizoids • Habitat: close to streams in forests
Division Psilophytaapp. 10 sp • Examples: Whisk ferns • Sexual reproduction by: spores • Description: No true leaves; plant looks like mass of green stems; rare; vascular • Habitat: Tropical rainforests
Lycopodiophyta or Lycophytaapp. 15 sp. • Examples: Club mosses • Sexual reproduction by: spores • Description: scale-like leaves and stems; has true roots; vascular • Habitat: Rich woods, undisturbed areas; rare; common and tree-like 300 million years ago