Plant Organs (Stem) - Cycle 2 Flashcards
Stem
- The organ bearing leaves and buds
- It elongates and orients the shoot in a way that maximizes photosynthesis by the leaves
- Lateral (side) branches grow from a lateral bud located at the angle where a leaf joins the stem.
Node
the location where leaves or buds are attached to the stem.
Internode
the region between nodes.
Functions
- Attachment for leaves, flowers, and fruits
- Conduction of water and minerals from the roots to all parts of the plant
- Storage of nutrients, organic molecules, water and by products
- Contains meristematic tissue for cell production
Stem Morphology: Axillary Bud
Lateral Bud
Stem Morphology: Petiole
Holds the leaf from the stem
Stem Morphology: Bud scale
protects the newly growing leaf
Stem Morphology: Bud scale scars
the bud scale will fall off and result to a bud scale scars
Stem Morphology: Terminal Bud
The top of the leaf
Stem Anatomy: Pith
- Made up of ground tissues
- They are made up of ground tissues and are similar in composition
Stem Anatomy: Dicot Stem
It has a ring of vascular bundles surrounding a central path
Stem Anatomy: Monocot Stem
Vascular bundles are scattered in ground tissue
Meristem: Apical
- Terminal and axillary buds of shoots; root tips
- Produces tissues that lengthen the tips of shoots and roots
Meristem: Lateral
- Internal cylinder along the length of roots and stems of woody plants
- Thickens roots and stems
Meristem: Intercalary
- Between nodes of mature stems in grasses and other monocots
- Regrowth of tissue if tip of stem is removed
Primary Growth (growth in length)
- Apical Meristems are located at the tips of all roots and stems and contribute to the increase in length of the plant.
- Tissues that develop from these apical meristems are part of the primary growth of the plant and give rise to the leaves and nonwoody stems and roots.
- Vascular Cambium
- xylem and phloem
- Cork Cambium
- bark
- one of the layers of bark
Secondary Growth (growth in thickness)
- Some plants have additional meristematic tissues (lateral meristem) that increase their diameter.
- These are the vascular cambium and cork cambium
- Tissues developing from them are considered part of the plant’s secondary growth
Secondary Growth (growth in thickness): Vascular Cambium
Grows in two directions to have both the xylem and the phloem to transport more nutrients for the plant.
Secondary Growth (growth in thickness): Cork Cambium
Only grows in one direction to protect the bark more.
Stem Plant Organs: Secondary Growth of Stem
- Begins with the initiation of the vascular cambium
- Production of secondary xylem and phloem is through the procambium (fascicular cambium)
- Interfascicular cambium will produce the new batch of ground tissue between the vascular bundles
- Forms a continuous ring of dividing cells called vascular cambium
Stem Plant Organs: Secondary Growth of Stem, Sources of Vascular Cambium
- Interfascicular parenchyma (interfascicular cambium)
- Procambium (fascicular cambium)
Annual Growth
- This growth will produce what we commonly see as rings
Annual Growth: Annual Rings
- Help us recognize the age of a tree.
- Thicker, darker rings mean it is formed during late summer, fall, and winter
- Thinner, lighter rings mean it is formed during spring and early summer
Stem Modifications: Rhizomes
Horizontal stems usually located beneath the soil surface
