1. Botany
Stems

2. Woody Twigs Vocabulary
Alternate-leaves spiral around stem
Opposite –leaves arranged in pairs
Whorled-leaves arranged in groups of three or more

3. Leaf Terms
Internode-distance between nodes
Blade-flat leaf part

4. Stem Terms petiole-leaf stalk Bud-can become branch, flower or scale
Terminal bud-at top of twig

5. More Stem Terms Bud scale scar-count to tell how old a twig is
Stipules-paired appendages
Deciduous-lose leaves annually
Leaf scar- left after leaf falls off
Bundle scar-location of xylem and phloem, characteristic for particular plants

6. Stem Origin and Development
Apical Meristem –
At tip of stem
Where cells divide
Makes stem longer

7. Primordia
Tiny embryonic leaves
Develop into mature leaves

8. Three Primary Meristems
Protoderm-outer layer becomes epidermis and is covered with a waxy , protective layer
Procambium-interior of protoderm, makes xylem and phloem
Ground meristem-makes p[arenchyma

9. Pith Made of parenchyma Large cells Breaks down after formed
Leaves hollow area

10. Cortex
Extensive
Replaced by
tissues from within
Function in storage

11. Vascular Cambium Narrow band of cells Becomes secondary tissues
Increases girth

12. Cork Arises within cortex Called cork cambium Made from cork cambium
Becomes filled with suberin
Cells die
Makes up outer bark
Reduces water loss
Protects against mechanical injury

13. Lenticels Pores for gas exchange in stems Spaces between cells
Fissures in the bark of older trees