Blahblah Stems

7/30/2019 Blahblah Stems

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Stems

Functions

Movement of materials

Water & minerals from roots to leaves

Manufactured food from leaves to roots Support leaves & reproductive structures

Food storage


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External Stem Structure

Lenticels

Breathing pores.

Bud Scale Scars

Show where terminal buds have been

located.

Leaf Scars

Show where leaves were attached.


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External Stem Structure

Terminal Bud

Bud on the end of the stem.

Axillary Lateral Bud

Bud on the side of the stem.


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The stem growserect& lifts the leaves ,exposing them tosunlight.it alsoconducts materialsfrom roots toleaves. Based onnature ofstem,plants aredivided into

herbs,shrubs &trees


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Function of Stems

supportleaves tomaximizelight

absorption part of

conduit fortransport ofwater,minerals,andorganicsolutes

storage


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Stem anatomy

Dermal, ground and vascular tissues

pith

cortexepidermis

Vascularbundles


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Types of Stems

Monocot stem Dicot stem Root


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Types of stems

Herbaceous vs. Woody

stems


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Tissues of stems

Epidermis (Dermal tissue type)

Provides protection

Has cuticle (wax) prevents water loss

Trichomes (hairs) for protection, torelease scents, oils, etc.


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Stem Vascular tissue

Vascular bundles composed of bothxylem and phloem

Xylem

Conducts water Support

Phloem

Conducts food Support

Vascularcambium


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Vascular cambium

Occurs in woody stems

Vascular cambium located in the

middle of the vascular bundle, between

xylem and phloem


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Vascular tissue: Trees

Vascular tissue is located on the outerlayers of the tree.

wood

phloem

xylem

bark

Vascular

cambium


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Girdling: cutting around a tree

Damages the phloem and xylem,

eventually killing the tree!


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Vascular tissue forms rings in

trees

Annual rings: xylem formed by thevascular cambium during one growing

season

One ring = one year


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History of the tree: annual rings

1489: Tree is planted

by Native American

1492: Columbus lands in

the Americas

1620: Pilgrims land

in Plymouth, Mass.

1776: Declaration

of US independence

1861: Start ofCivil War

1969: Man

lands on Moon

1917 & 1945: Tree

Survives two World

Wars

1971: Birth Year

of the IDIOT

who cut down

this tree!!!

Dendrochronology : tree time-keeping


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Internal Stem Structure

(Monocots) Vascular bundles

contain both xylem

& phloem. Examples:

Grasses

Corn


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Monocot Stems

(Vascular Bundle)


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(Dicots) Plant stems have

xylem & phloem

separated by thecambium.

Example:

Trees


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(Dicots)


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Specialized Types of Stems

Corm

Underground

Solid, fleshy, scale

covered

Examples

Gladiolus

Crocus


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Bulb

Layers of fleshy

scales that overlapeach other

Underground stem

Examples

Tulips

Lilies

Onions


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Tubers

Food Storage Area

Short, thickunderground stem

Examples

Potato

Caladium


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Crown

Closely grouped

stems or plantlets Just above or

below ground

Examples

African violet Ferns


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Spurs

Short stems found on

woody limbs adaptedfor increased fruit

production

Examples

Apple

Pear


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Rhizomes

Underground stems

that produce roots onthe lower surface and

extend leaves and

flower shoots above

ground Examples

Iris

Lily of the Valley


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Stolens

Stem that growshorizontally above

the soil surface

Examples

Strawberries Airplane Plant


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Stolens

Stem that growshorizontally above

the soil surface

Examples

Strawberries Airplane Plant


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ARIEL MODIFICATIONS OF STEM

TENDRILSIN grapes

Axillary bud is

modified into

tendrils.

CLADOPHYLL

/

PHYLLOCLADE

The entire

shoot is

flattend & leaf


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CLADODEBranch of asingle internodewhich is

flattened tostimulate a leaflike.

BULBILINDIOSCOREAIt is a modifiedfloral bud whichbecomes

vegetative

CLADODE

ACACIA

BULBIL

DIOSCOREA

Blahblah Stems

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