1. Wonderful World of Stems

2. Stinging Hairs
Urtica dioica

3. Dendrocnide excelsa
Australian Stinging Tree, Dendrocnide excelsa

4. Dicot vs. Monocot Stems

5. Fibers (sclerenchyma)

6. Vascular Bundles
C.s. of a dicot
vascular bundle

7. Fibers for Stem Strength

9. Vascular Cambium

10. Vascular
Cambium
Secondary
Xylem
Secondary
Phloem

12. Axial and ray systems

14. Annual growth rings Early wood larger cells Spring wood
Late wood smaller cells
Summer wood

15. Bristlecone Pine Dendrochronology dated one at 5,000 years old
(and counting!)
1,000 growth rings packed into just 13 cm. of wood

16. Sequoia semperivirens
Tallest living organism (112 m.) – the ‘Mendocino Tree’
Weighs 1,600 tons (or 10 blue whales)
Roots only 1.8 m. deep!
Average Sequoia uses 1,100 L of water per day

17. Castanea
World’s fattest tree at 58 m. diam., found on Mt. Etna, Italy, the “Tree of One Hundred Horses”

18. Secondary growth - bark

21. Phellum (cork) (dead)
Cork cambium
Phelloderm
(living)
Epidermis fracturing, with periderm below

22. Old periderm often called, “outer bark”

23. Pine bark
Eucalyptus bark

24. Lenticels

25. Girdling

26. Softwood

27. Hardwood

28. Heartwood
(inactive)
Sapwood
(active)

29. Transverse = cross section
Radial + Tangential = longitudinal sections

30. Wood Knots

31. Wood grain

32. Wood Density
Guaiacum officinale

33. Some plants grow tall without secondary growth:

34. Stem types
Stolon
Rhizome
Bulb
Corm

35. Stem Types
Cladode
Tendril
Tuber