What Makes Leaves Strong

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Vascular bundles are composed of
Xylem which conducts water,
Phloem which conducts sugar, and
Fibers
which support and protect the xylem and phloem.

Leaf Veins are Vascular Bundles & may have a
Fibrous Bundle Sheath.
SCaneVeins400Lab.jpg (128878 bytes)  
Note the Veins in the Leaf of ko (Sugarcane)!

ScaneDraw3DOverallCropLab.jpg (252680 bytes)
Three Dimensional drawing of a Sugarcane Leaf

Image62.gif (27250 bytes)
Sugarcane (ko) Leaf Section: The large central vein is encased by fibers & is an FVB

"Fibrovascular" Bundles (FVBs)
(fibro = fibers; vascular = xylem & phloem)
are veins surrounded by large Fibers.

PiliVBLab600.jpg (118433 bytes)

Section through a leaf of Pili Grass showing a Fibrovascular Bundle

Monocots have Many Parallel Veins in their Leaves.

Common Local Examples of Monocots with Parallel Veins
hala (Pandanus)
ki (ti;
Cordyline)
niu (Coconut Palm; Cocos)
ko (Sugarcane;
Saccharum)
uki uki grass (Dianella)

TiPlant.jpg (9010 bytes)
ki (Cordyline) Note the Waxy Leaves.
Image59.gif (46812 bytes)
niu (Coconut; Cocos) is a Monocot with many parallel veins in its leaf
TiLeafRedScanWholeAdaxial.jpg (79735 bytes)
Upper surface of a ki Leaf
TiAdLeafRedScanPart600Crop.jpg (166009 bytes)
Upper Surface of a ki leaf showing the Veins
TiParalel.jpg (29011 bytes)
ki Leaf
showing many Veins.
ParVeinWhoMont.jpg (12656 bytes)
Monocot Leaf with many parallel veins.
Image61.gif (22266 bytes)
Midrib of a ti Leaf
Note the many Fibrovascular bundles!!!!!
TiLfMribTBLModLab.jpg (244784 bytes)
Midrib of a young ki leaf: The cells that stained blue are Fibers with extremely thick walls.

The Fibers and the Xylem in Fibrovascular Bundles make
leaves strong.

UkiUkiLfMacroVeins600Lab.jpg (172341 bytes)

UkiUki.jpg (17200 bytes)
uki uki   grass (Dianella) also has parallel veins in its leaves. These are responsible for its utility.
UkiUkiTBLab.jpg (124288 bytes)
Uki Uki Leaf Section: Note the Fibrovascular Bundles. Alsonote the Cuticle.

Some of these were used by Hawaiians to make various types of twine and cordage!

Agave Leaves

Pure Fiber Bundles can be  present in  Leaves.

agavexst.jpg (15612 bytes)

Section through an Agave Leaf: The Blue color signifies the presence of Lignin.

Agave is still used as a source of coarse fibers. It was grown in Hawaii & plants have escaped cultivation.

agavbund.jpg (11166 bytes)
The Vascular Bundles are surrounded by Fibers (Fibrovascular Bundles).

agavfbnd.jpg (6080 bytes)
Bundles of pure fibers
(Fiber Bundle) are also present.

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