Download Plant form and function

Plant Form and
Function
Plant organs
Plant organs
• Root system – roots
• Shoot system – stem and leaves
• Vegetative organs – (allow to live and grow): roots, leaves,
stem
• Reproduction: flowers, seeds and fruits
Roots
• Underground, usually equal to shoot system in size
• Anchors and gives support
• Absorbs water and minerals
• Penetrates soil as it grows
• Root hairs increase surface
area
• Produce hormones
Root organization
• Root cap – apical meristem, replaced often
• Zones
• Cell division – primary meristem, mitosis
• Elongation – cells lengthen and specialize
• Maturation – root hairs, fully differentiated
Stems
• Main axis of plant
• Support leaves so that leaves are exposed to as much light as
possible
• Node – where leaf is attached
• Internode – space between nodes
• Vascular tissue used in transport
• Can store nutrients and water and conduct photosynthesis
Leaves
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Photosynthesis
Size, shape and texture vary and is used in identification
Blade – wide portion of leaf
Petiole – stalk, attaches blade to stem
Axillary bud – where branch or flower may originate
Leaf anatomy
Plant tissues
• Meristematic tissue = embryonic
• Apical meristem – located on tip of stem and
roots, primary growth
• Lateral meristems – secondary growth
• Woody (non herbaceous), non woody
(herbaceous – perennial, dies back in winter)
Woody Stems
• Primary (length) and secondary (girth of trunks) tissues
• Secondary tissues form from lateral meristem:
• vascular cambium – produces secondary xylem (wood)
• Vascular cambium produces new xylem and phloem each year
• cork cambium – produces a tough covering that replaces
epidermis early in secondary growth
• 3 distinct areas:
• Bark – all tissues outside the vascular cambium, living part of tree
• Contains phloem, can kill a tree if damaged
• Wood – xylem, almost all is dead when it functions
• Cork
Secondary growth of trees
Vascular tissue
• Xylem – water and minerals, roots to leaves
• Phloem – sucrose and organic molecules
(hormones) form leaves to roots
• Complex tissues – contain 2 or more kinds of
cells
• Both extend from roots to leaves
• Roots- located in vascular cylinder, stem – vascular
bundles, leave – leaf veins
Vascular tissue