Chapter 6 - Stems Flashcards
Node
The area/region (not structure) of attachment, where leaf, bud, stem, fruit, flower, thorn, branches are attached
Internode
Stem region between nodes; no attachments
Blade
Flattened part of leaf
Petiole
Stalk by which a blade is attached to a stalk
Axil
Angle between a petiole and the stem
Axillary bud/lateral buds
Bud located in the axil. Contains meristematic tissue, same as terminal bud. Not all buds will produce all the potential parts (leaves, stems, flowers, etc.)
Bud scales
Protect buds (against water loss) while they grow, then fall off. Not all buds have them
Stipules
a
Deciduous
Trees or shrubs that loose all their leaves annually
Leaf scars
Where a leaf was attached to a stem. Shapes can help with plant identification (triangular vs. round, etc.)
(Vascular) Bundle scars
Marks (dots) within a leaf scar where the vascular bundles (vascular cylinders) were. The shape and size of the leaf scars and the arrangement and numbers of bundle scars are characteristic for each species and so can be useful in tree/plant ID.
Pith
Center of herbaceous dicot stems (parenchyma cells)
Cortex
a
Vascular bundles
In herbaceous stems, clumps of vascular tissue (xylem and phloem) scattered throughout the stem.
Woody dicotyledonous stems
- Consist of outer bark, cork cambium, inner bark, vascular cambium and wood
Heartwood
- Older, non-transporting xylem
- Function: support/strength; like a big cement pole through the center of the tree
- Usually turns a dark color because the cells filled in with various chemicals; every tree has its own chemicals it uses; can resist fungus, etc.
- Osage orange/hedge apple - chemicals keep wood from rotting for ~40 years. Branches used as fenceposts
Sapwood
- Newest, active-transporting xylem, but not “living” tissue
- Lightest colored wood
- Not always evenly-distributed around the tree (light, gravity, weather can cause damage and unevenness)
- Function: transport, strength/support, some storge (sugars in winter)
Vascular rays
- Chains of parenchyma cells
- Like spokes on a wheel
- Lateral transport
- Provides protection against diseases
- Makes very thin lines
Bark
- Periderm
- Outer bark - protection from fungus/insects/animals, temperature, water loss (with suberin)
- Inner bark - Phloem of the tree
- Cork cambium - Between the outer and inner bark; produces the outer bark as it sloughs off
Specialized stems
1) Adventitious stems
2) Rhizomes
3) Stolons
4) Tubers
5) Tendrils
6) Bulbs and Corms
7) Thorns
Rhizomes
- Specialized (modified) stem
* An underground stem, like bamboo; sends out runners, then sprouts
Stolons
- Specialized (modified) stem.
* Grows above ground, away from parent plant. Where touches ground, a new plants takes root. (strawberries)
Tubers
- Specialized (modified) stem.
* Grows underground and stores energy (starches). (Idaho potatoes - have eyes/nodes which sprouts new growth)
Bulbs and Corms
Like onions