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internships
• Chicago Botanic Garden
• www.chicagobotanic.org/internship
• range of opportunities
• most start in May & pay $9/h
• most positions will have been filled by
2011
April 15,
origin of botanical science
• botany = study of plants
– previously subfield of medicine
• today ethnobotany (subfield of botany)
– includes medical uses of plants
• assumed plants like animals
– vascular tissue, veins
• outer structure, form = morphology
• inner structure = anatomy
plant structure
--shoot
• shoot = stem + leaves
• stems:
– support
– conduct H2O
• leaves: PS
• nodes & internodes
plant structure--roots
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•
•
•
•
anchor plant
absorb, conduct H2O & minerals
storage (old root)
root hairs increase surface area (SA)
Fig 35.3
plant growth
• indeterminate growth—
keep growing
• meristems—
growing parts of plant
• 1) apical: top or bottom of plant-->
main shoot or root
• 2) lateral bud assoc w/leaf-->branch
(shoot w/own leaves & buds)
stem & root anatomy
• dermal tissue at surface
• vascular tissue in center,
ring, or scattered (eg corn)
• ground tissue elsewhere
– has intercellular spaces
leaf structure
• stomata usually on bottom
– less water evap
• densely packed cells on top
– for capturing light
• loosely packed cells below
– for gas exchange
• vascular tissue = veins
– distribute nutrients
unity of the plant body
• Campbell Fig 35.8
• 3 tissue systems
continuous
plant cells
• cell walls
– cellulose
– support
• vacuole
– turgor
(H2O
pressure)
– waste
Fig 35.27
intercellular
connections
(plasmodesmata)
“inter” between
“intra” within
plant cell types
• 1. parenchyma:
unspecialized, polyhedral cells
• 2. collenchyma:
unevenly thickened primary walls
• 3. sclerenchyma: thick 2ndary walls
– lignin: support & protection
• fibers: elongate
– 9 to 70 mm long in flax!
• sclereids: stone cells
– pears, nuts
<—fiber
x-sec & l-sec
1. dermal tissue
• epidermis
– protects, no airspaces
• stomata, guard cells
– gas exchange
• hairs—protection, absorption
• cuticle (waxy)
– waterproof
2. vascular tissue
• a) xylem conducts H2O
• primary walls thin, first
• secondary walls thick, inside
– helical can stretch
– pitted allow lateral transport
• lignin: strength, waterproofing
• cells dead at maturity
• b) phloem conducts food (sugar)
• sieve-tube elements alive (active
membrane), but no nucleus
• neighboring “companion cell” helps out
• sieve-tube elements & companion cells
connected via plasmodesmata
3. ground tissue
• NOT dermal or vascular
• mostly undifferentiated cells
forensic botany
• identify distinctive resistant parts
• cellulose, lignin not digested; seeds
• id of plant parts attached to clothing
--> location
• Lindbergh case—wood anatomy
• stomach contents—last meal