Wonderful World of Stems

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Wonderful World of Stems
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Stinging Hairs
Urtica dioica
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Dendrocnide excelsa
Australian Stinging Tree, Dendrocnide excelsa
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Dicot vs. Monocot Stems
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Fibers (sclerenchyma)
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Vascular Bundles
C.s. of a dicot vascular bundle
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Fibers for Stem Strength
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Vascular Cambium
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Vascular Cambium
Secondary Xylem
Secondary Phloem
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Axial and ray systems
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Annual growth rings

• Early wood larger cells
• Spring wood

• Late wood smaller cells
• Summer wood

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Bristlecone Pine

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

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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

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Castanea
Worlds fattest tree at 58 m. diam., found on Mt.
Etna, Italy, the Tree of One Hundred Horses
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Secondary growth - bark
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Phellum (cork)(dead)
Cork cambium
Phelloderm (living)

• Epidermis fracturing, with periderm below

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• Old periderm often called, outer bark

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Pine bark
Eucalyptus bark
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Lenticels
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Girdling
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Softwood
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Hardwood
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Heartwood (inactive)
Sapwood (active)
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Transverse cross section Radial Tangential
longitudinal sections
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Wood Knots
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Wood grain
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Wood Density
Guaiacum officinale
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Some plants grow tall without secondary growth
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Stem types
Stolon
Rhizome
Bulb
Corm
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Stem Types
Cladode
Tendril
Tuber
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