Forests

Importance

• 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

http://www.google.com/imgres?imgurl=http://www.robinsonlibrary.com/science/botany/anatomy/graphics/leaftypes.gif&imgrefurl=http://www.robinsonlibrary.com/science/botany/anatomy/leafparts.htm&usg=__UVdPJicsEmVxSDqNL6hRv9CFxp8=&h=382&w=500&sz=74&hl=en&start=5&zoom=1&tbnid=0cUTxdDM3BnP1M:&tbnh=99&tbnw=130&ei=5UeUTvqjEsStsALploHwAQ&prev=/search%3Fq%3Dparts%2Bof%2Ba%2Bleaf%26hl%3Den%26safe%3Dstrict%26gbv%3D2%26tbm%3Disch&itbs=1

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

• Support leaves• Transport materials• Provide storage

Stems

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