Transcript Parts of a Plant and Their Function

Forests
Importance
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Wildlife habitat
Soil Erosion
Wind block
Aesthetics
Fuel
Climate moderation
Plants
• Primary source of energy
– Sun -> grass -> deer -> humans
• Carbon cycle
– Take in carbon dioxide, produce glucose and
oxygen
Bit of History
• Tall grass prairies and forests
– Resources for homes & agriculture
– Mid – 1800s approx 6.7 million forested acres (1/5)
– By 1900s only 1.5 million acres remained
• Breadbasket of the world
– Forest cover has increased to 2.1 – 2.5 million acres
• Result from less livestock grazing
• State & Federal cost – sharing reforestation programs
Parts of a Forest
Succession
Parts of a Plant
Parts of a Plant
• Four basic parts
– Leaves
– Stems
– Roots
– Flowers (fruit/seeds)
Leaves
• “Food Factory” through photosynthesis
• Leaf is made of specialized cells
• Vary in shape, size, and arrangement
– Help identify plants
– Simple, compound
– Toothed, pointed, smooth
– Lobed, ovate, lanceolate
– Whorled, alternate, opposite
Parts of a leaf
• Food manufactured in leaf moves down
through the stem to the roots
– Used or stored in stem or root
• Sometimes cells in roots, stems, and leaves
– Respiration
• Oxygen used to produce energy for cells
• Too much water can affect efficiency
Stems
• Support leaves
• Transport materials
• Provide storage
Types of Stems
• Woody or nonwoody (herbaceous)
• Stolons
– Grow along soil surface
– Produce new plants
• Tuber
– Store energy
• Cacti
– Green fleshy stems
– Store water and photosynthesis
• Modified for protection
Stem Structures
• Did you know that a sign nailed 2m (7ft) high
on a tree will remain at that height, even
though the tree may grow much taller?
Stem Structure
• Grow in length only at tip
• Apical meristems
– Primary tissues
• Lateral meristems
– Secondary growth (diameter)
Stem Features
• Node
– Leaf attaches to stem
• Internode
– Space between nodes
– Lateral bud
• Bud
– Stem or leaf
– Apical meristem enclosed by bud scales
Winter Identification of Trees
Primary Growth in Stems
• Apical meristem
– Dermal, protect plant
– Ground, cortex and pith
• Pith located at center of stem
– Vascular tissue, occurs in bundles
• Xylem (inside) and phloem (outside)
Secondary Growth in Stems
• Stems increase in thickness
– Cell division in vascular cambium (xylem/phloem)
– Dicot and gymnosperms (Monocot Trees may differ)
• Stem forms b/w xylem and phloem in vascular bundle
– Vascular cambium
• produces 20 xylem (inside) and phloem (outside)
– 20 xylem represents the wood of the plant
• New cambium cells increases stems diameter
Cross Section of Woody Stem
• Older xylem stop producing water
– Darken wood called heartwood
• Will increase in diameter
– Lighter – colored wood called sapwood
• Stays about the same
• Phloem near outside of stem
– Bark
• Cork, cork cambium, and phloem
– Protective layer
– Cork cells die at maturity
• Cannot elongate and will rupture as stem increases in
diameter
• Bark pattern (maples and oaks)
Annual Rings
• Springwood
– Water plentiful
– Vas. Cambium form new xylem cells
– Wide and thin cell walls
• Summerwood
– Water scarce
– Vas. Cambium forms smaller thicker cells
• Difference causes a change in appearance
• One ring each year used to determine age
Transport of Water
• Water and mineral nutrients occur in xylem
• Water is constantly evaporating from plant
– Stomata
– Transpiration
Roots
• Anchor the plant in the soil
• Absorb and transport water and mineral
nutrients
• Storage for water and organic compounds
Types of Roots
• Taproot
– Primary root
– Rarely more than one – two meters
• Fibrous root system
– Numerous small roots
• Adventitious roots
– Specialized roots grow from other places
– Leaves and stems
– corn and epiphytic orchid (aerial roots)
Root Structures
• Root cap
– Covers apical meristem
– Produces oil
• Root hairs
– Extensions of epidermal cells
– Increase surface area
• Dependent on stems and leaves for energy
• Store starch
Reproduction of Plants
Propagation
Sexual and Asexual
• Asexual
– No seeds
– Leaf, stem, or root
• Sexual
– Union of pollen and egg
– Pollination
– Fertilization
• Pollen tube, male gametes unite with egg cell to form
zygote
Pollination
• Transfer of pollen
• Pollen grains
– Pores where pollen tubes grow
• Self – pollination
• Cross – pollination
• Wind or animal