Chapter 6 - Stems Flashcards
Anatomy of a woody twig
- Nodes
- Internodes
- Leaves
- Axiallary bud
- Terminal bud
Leaves
- Petiole (Sessile)
- Blade
- Stipules ( estipulate)
- Axil - the angle between leave and stem. Inside is the axillary bud
- Leaf scar - when leaf brakes off.
Terminal bud
- bigger than the axillary bud
- Apical meristem
- Bud scales - grow to protect buds. has antifreeze. there are bud scale scars that distinguish from last years growth to this year
Shoot apical meristem at growing tip:
- Protoderm - formed from posteior part
- Ground meristem -
- Procambium - forms vascular bundles. (Stele)
Stele Patterns
- Protostele - xylem in center and phloem around it
- Siphonostele - pith is in the center and vascular tissues are around it
- Eustele - common in flowering plants
Procambium
- stele patterns
- leaf and bud gaps
Origin of secondary growth
Vascular cambium
Cork cambium
Vascular Cabimum
- in Dicots
- Between primary xylem and phloem
- Divide horizontally
- Form secondary xylem (inside) & phloem (outside), between is the vascular cambium
Bulb vs. Corm
In a Corm the food is stored in the stem itself, not the leaves.
Cladophyll
Photosynthetic stem/Branch, usually flat
examples; prickly pear cactus, broccoli, asparagus
Thorns, Spines and prickles
Thorns are modified stems.
Spines are modified leaves.
Prickles are an outgrowth of the epidermis
Tendril
a specialized stem that wraps around objects. It can be a modified stem.
Tissue Patterns in Stems
- Herbaceous Dicots
- Woody Dicots & Conifers
- Monocots
Herbaceous Dicots
- Almost all growth is primary
- Vascular bundles in cylinder
- Have rays of parenchyma
Woody Dicots & Conifers
EFFECT OF CELL DIVISION IN VASCULAR CAMBIUM
- Cambium cells divide laterally
- Ring of vascular tissue forms, gaps for rays
- Xylem
- Phloem
—Crushed or to cork cambium
— Lactifers - secrete latex, milky white substance example: rubber and gum
- Vascular rays - living parenchyma cells, rays cells extend multiple year. Conducts water and dissolves nutrience.
- Resin Canals
