Transcript Plant Organs

Plant Anatomy
1. Plant Parts a.k.a. Plant Organs
2. Plant Tissues
3. Water Transport
4. Food Transport
Plant Parts/Organs
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Root
Stem / Shoot
Leaf
Reproductive
Root Function
 1. support and anchor plant
 2. absorb water and minerals from soil
 3. transports water and minerals to stem
 some also serve as food-storage
e.g. maple trees, carrots
Root Types
 Taproots
 a long, thick main root with
branching secondary roots
 in dicots
 e.g. dandelions, carrots
 Fibrous Root
 many main roots about the
same size
 not as deep in the ground
but extends laterally
 in monocots
 e.g. grass
Root Structure
 In the center of the root is the vascular cylinder
(vein) – xylem and phloem.
 Roots grow from the tips where the apical
meristem is found and protected by the root
cap.
 In the zone of differentiation root hairs are
found. Root hairs increase the root’s surface
area and is where water and minerals are
absorbed.
Cross Section of Growing Root
Page 394
Root Modifications
Adventitious roots –
prop roots of corn
Pneumatophores –
mangrove swamps
Epiphytes –
strangler fig
Aerial roots – develop along stem
as in ivy
Modified storage of beets
Stem Function
 1. support the leaves
 2. transport water and minerals from root to
leaves
 3. transport sugars from leaves
 some may store food
e.g. sugar cane
Stem Types
 Herbaceous Stems
 stems that are green,
soft and regrown each
year
 Woody Stems
 stems contain thick,
tough tissue – wood
 allows plants to live for
more than 2 years and
grow taller than 1 meter
 hard tissue called wood
is dead xylem
Stem Structure
 must have vascular cylinder (vein) containing xylem
and phloem
 Xylem is always closer to the centre of the stem.
 Phloem is always closer to the outside of the stem.
 In monocots vascular bundles are scattered throughout
the stem.
 In dicots vascular bundles are arranged in rings.
 In woody stems
 sapwood is younger xylem – conducts water, on outside
 each year a new ‘ring’ of sapwood is laid down –annual
rings
 heartwood is older/dead xylem – filled with resins giving
it a darker color; can’t conduct fluids
 bark is the protective layer on the outside – consists of
cork and phloem
Stem Modifications
Leaf Function
 to act as solar panels trapping sunlight to
convert carbon dioxide and water into
glucose by the process called
photosynthesis – create food for the plant
 plants now are ‘food’ for organisms
 photosynthesis also produces oxygen
Leaf Types
 broad verse narrow
 simple verse compound
 needles of
gymnosperms
Leaf Structure
 contain chlorophyll to photosynthesize – thus are
green
 designed to maximize exposure to sunlight – thus
tend to be wide
 contain special cells to protect against excessive
water loss and damage – cuticle and epidermis
 have special cells to allow gases (CO2, O2, H2O )
to be exchanged – guard cells form stomata
 contain veins to transport need water and
produced glucose
Cross Section of a Leaf
Leaf Modifications
Spines – of cacti
Tendrils – of grapevine
Venus fly trap
Petal – of
flowers
Storage leaf – onion
Succulents –
jade plant
Reproductive Organs
Ferns - spores
Gymnosperms – cones
Angiosperms – flowers