roots and stems - botany lab semi finals
DESCRIPTION
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Roots
Plant organ systems
What are the primary functions of roots?
Fibrous and taproot systems
Dicots Monocots
Root structure
Root cap
• Parenchyma• Perception of
gravity
Notice how the growing zone has no root hairs or lateral roots!
Growth among soil particles would result in shear forces.
Zone of Maturation - cell differentiation
ProtodermGround MeristemProvascular
Zone of Cell Elongation - cell expansion
Zone of Cell Division - new cells by mitosis
Root Cap - penetration, padding
Mucilage Slough Cells
Root Tip Senses GravityAuxin Hormone ProducedAuxin Accumulates on LowerGrowth Inhibited on Lower…Relative to UpperRoot Curves Downward
Gravitropism
Root Hairs Increase Surface Area
Root Hairs Secrete Acid (H+)
H+ Cation Exchange w/Minerals
Mineral Uptake into Roots
Water and Mineral Uptake
Region of maturation
Mature root structure
Monocot root, c.s.
Dicot root, c.s.
Phloem
Xylem
Endodermis
Endodermis regulates mineral absorption
Lateral (branch) roots
Endodermis Pericycle
Endodermis Pericycle
Specialized roots• Storage roots
Propagative roots
Pneumatophores
Aerial roots
Aerial roots – velamen (orchids)
Contractile roots
Prop roots
Root nodules
Root nodules
Parasitic roots• Witchweed
•Support
•Conduction
•Growth
Stem functions
Vascular bundle arrangementof roots and stems
Roots
Stems
Monocot Dicot
Dicot stem anatomy
Coleus stem vascular bundles
Dicot stem anatomy
Secondary growth of dicot stems
heartwood sapwood
secondary xylem
secondary phloem
Annual rings of phloem
phloem
fibers
LenticelsLenticels
Lenticels
Specialized stems
Cladophyll
Thorns
Tendrils
That’s a big stem!• Baobab (Adonsonia digitata) grow up to
45 ft. in diameter
That’s a big stem!
Redwoods grow up to 350 ft tall; 30 ft. dia.
Bristlecone pines
• Oldest organism – 4767 yrs. old