Stems

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Stems

• C9L3P4
• Plant Organs

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Stems

• The part of a plant that connects its roots to
  its leaves is the stem.
• Stems support branches and leaves, and their
  vascular tissues transport water, minerals, and
  food.
• Plant stems are usually classified as either
  herbaceous, which are usually soft and green, or
  woody, which are stiff and typically not green.

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Types of stems

• Herbaceous stems
• Woody stems

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Herbaceous stems

• Softer, more flexible type of stem
• Supported by cell walls and turgor pressure
• Woody plants often begin as herbaceous and then
  become woody as the grow older

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Woody stems

• Hard and not very felxible
• Capable of supporting a lot of weight
• Examples trees and shurbs

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Stem Functions

• manufacture, support, and display leaves
• conduct materials

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Monocot Stem
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Dicot Stem
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wood

• a collection of layers of xylem that have built
  up over several years

The oldest layer of xylem is at the center of the
woody plant part newest layer is the outermost
layer
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Kinds of Wood

• Heartwood - dead xylem cells that are often
  darker
• Sapwood - xylem that conduct water and minerals

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Heartwood Sapwood
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Kinds of Wood

• Springwood - xylem cells that develop early in
  the growing season
• Summerwood - small, thick-walled xylem cells
  that develop later in the growing season

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Springwood Summerwood
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Kinds of Wood

• Hardwood - comes primarily from angiosperms
  (oaks, maples, walnut, cherries)
• Softwood - comes primarily from gymnosperms
  (firs, pine, cedars, spruce)

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Hardwood
Softwood
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Heartwood Sapwood
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bark
the outer covering of woody plant parts(makes new
xylem and phloem cells)
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cork
(the outer layer of bark) tough, thick-walled
cells forming the outer layer of bark in woody
plant stems made of dead, thick-cell walls
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cork
heartwood
forms a tough, water proof coating that keeps
harmful organisms out and moisture
Annual growth ring
sapwood(xylem)
phloem
cork
vascular cambium
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cork cambium
a layer of living cells just under the dead cork
(produces new cork cells)