The Plant Body

• plant cell walls are made with cellulose
• Plant cells produce a waterproof filler called Lignin that fills space between cells
• Lignin is the primary compound that makes up the bulk of wood

Meristems:

• Totipotent stem cells that last their entire lives
• These turn into differentiated cells called tissues that compose plant organs
• Apical Meristem- growth from tips (responsible for primary growth)
• Lateral Meristem- responsible for secondary growth (increasing diameter/girth) woody plants have 2 lateral meristems

• Cork cambium- contributes to outer bark
• Vascular cambium- found between secondary xylem and secondary phloem
• Secondary xylem= wood

• When an apical meristem is removed, the axillary buds grow new shoots

3 basic Primary meristems:

1. Protoderm: gives rise to dermal tissues (skin tissues)

• Mainly for protection
• Guard cells: breathing
• Trichomes: protection from herbivores
• Root hairs: surface area
• Cuticle: protection from dehydration

2. Ground Tissues:

• Parenchyma

• Unspecialized functions:
• Photosynthesis
• Store water and nutrients

• Collenchyma

• Thickened walls at angles
• Supportive (like threads in celery)

• Sclerenchyma

• Dead when mature
• Very thick walls of lignin
• Support, protection, scars
• Example: Sclereids

3. Procambium: grows into the Vascular Cambium:

• Xylem and phloem
• Xylem:

• Conducts water and solutes one way from roots to shoots by adhesion/cohesion, water potential and transpiration
• Made up of tracheids or vessels
• Dead when mature with lots of lignin left over (aka wood)

• Phloem:

• Living tissue (live at maturity)
• Transports sugars, hormones, other solutes dissolved in water up and down and all around by Translocation
• Two cell types:

• Sieve cells (no nuclei)
• Companion cells (control cytoplasm of sieve cells)

Finish taking notes on

• Leaves (types)
• Roots (types)

• Pneumatophore: breathing root
• Contractile: can hold in sandy soils
• Parasitic:
• Food storage: store food (beets)
• Water storage: store water
• Buttress:

• Stems

• Bulbs:
• Corms:
• Rhizomes: grow laterally underground
• Runner and Stolons: horizontal stem growing above ground
• Tubers: modified part of stem that stores food or water and for asexual reproduction
• Tendrils: curls and pulls the plant along
• Cladophylls: flattened stems; photosynthetic branches

Plant Life Spans:

• Annuals:

• Plant ages and dies at the end of one growing season
• Must flower and fruit to produce next generation

• Biennials:

• Two years to complete life cycle
• Many require vernalization (cold period) before they will flower

• Perennials:

• Above ground vegetation usually dies -finish-