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Other tissues Anatomy of stem

Introduction to Botany. Lecture 6
Alexey Shipunov
Minot State University

September 8th, 2010

Shipunov

BIOL 154.6


Other tissues Anatomy of stem

Outline

1

Other tissues Poikilo- and homoiohydricity Absor ption tissues Secretor y tissues Additional meristems Anatomy of stem From SAM to primary structure Vascular bundles

2

Shipunov

BIOL 154.6


Other tissues Anatomy of stem

Outline

1

Other tissues Poikilo- and homoiohydricity Absor ption tissues Secretor y tissues Additional meristems Anatomy of stem From SAM to primary structure Vascular bundles

2

Shipunov

BIOL 154.6


Other tissues Anatomy of stem

Poikilo- and homoiohydricity Absorption tissues Secretory tissues Additional meristems

Poikilo- and homoiohydricity

Poikilohydric plants do not save water, they survive even complete desiccation Homoiohydric plants save water, they always have similar water content and do not survive after desiccation Compare with poikilo- and homoiothermic animals (reptiles vs. mammals)

Shipunov

BIOL 154.6


Other tissues Anatomy of stem

Poikilo- and homoiohydricity Absorption tissues Secretory tissues Additional meristems

Origins of poikilo- and homoiohydricity
Increasing of biomass competition 3D growth increasing of weight Support tissues further increasing of weight ? Cam
b?? m iu ?? ?? ?? ?? Li g @A / jjj jjjj tjjjj

Life on thejair and TTnder the sun u TT jj TTTT jjj

TTTT TTTT T*

Anabiosis
ED

oo ooo ooo wooo

drying O OO

OOO OO'

Poikilohydricity

water abs? btion o Myco
r? iza h ?? ?? ? ?? ?? ?



Epidermis wit cuticlOOO h e

OOO OO'

transpiration Stomata


Vascular tissues




Absorbing tssues i

Homoiohydricity

ni n Root system
/

Big height


separation from gametophyte Seed
Shipunov BIOL 154.6



Other tissues Anatomy of stem

Poikilo- and homoiohydricity Absorption tissues Secretory tissues Additional meristems

Absorption tissues

Always primar y, simple tissues Rhizoderm, or root hairs, originates from protoderm, but life span is much shor ter than of epidermis Velamen, originates from root cor tex

Shipunov

BIOL 154.6


Other tissues Anatomy of stem

Poikilo- and homoiohydricity Absorption tissues Secretory tissues Additional meristems

Rhizoderm

Root hairs of grass seedlings (LM)
Shipunov BIOL 154.6


Other tissues Anatomy of stem

Poikilo- and homoiohydricity Absorption tissues Secretory tissues Additional meristems

Velamen

Outer cylinder is a velamen tissue of orchid root (LM, c D. Webb)
Shipunov BIOL 154.6


Other tissues Anatomy of stem

Poikilo- and homoiohydricity Absorption tissues Secretory tissues Additional meristems

Secretory tissues

Primar y, simple or complex tissues Spreading across plant body, concentrating in leaves and young stems May secrete latex, volatile oils, mucus and other chemicals Functions var y: attraction or dis-attraction, communication, defense etc.

Shipunov

BIOL 154.6


Other tissues Anatomy of stem

Poikilo- and homoiohydricity Absorption tissues Secretory tissues Additional meristems

Laticifers

Shipunov

BIOL 154.6


Other tissues Anatomy of stem

Poikilo- and homoiohydricity Absorption tissues Secretory tissues Additional meristems

Additional meristems

Intercalary meristems: locate in stems, regulates stem elongation Marginal meristems are leaf-specific, they regulate shapes Repair meristems help to cure wounds, they form buds and roots in unusual places

Shipunov

BIOL 154.6


Other tissues Anatomy of stem

Poikilo- and homoiohydricity Absorption tissues Secretory tissues Additional meristems

Classification of tissues

Classification table: discussion Tissues Simple Complex Primary ... ... Secondary ... ...

Shipunov

BIOL 154.6


Other tissues Anatomy of stem

From SAM to primary structure Vascular bundles

Protoderm to epidermis

Stem apex meristem (SAM) produces protoderm Protoderm cells differentiate into epidermal cells

Shipunov

BIOL 154.6


Other tissues Anatomy of stem

From SAM to primary structure Vascular bundles

Ground meristem to cor tex and pith

SAM produces also ground meristem Ground meristem differentiates into cortex and pith Procambium raises between cor tex and pith, it forms vascular bundles or vascular cylinder

Shipunov

BIOL 154.6


Other tissues Anatomy of stem

From SAM to primary structure Vascular bundles

Three primary meristems: procambium, protoderm and ground meristem

Shipunov

BIOL 154.6


Other tissues Anatomy of stem

From SAM to primary structure Vascular bundles

Young stem with primary tissues

Shipunov

BIOL 154.6


Other tissues Anatomy of stem

From SAM to primary structure Vascular bundles

Older stem with hollow in the center

Shipunov

BIOL 154.6


Other tissues Anatomy of stem

From SAM to primary structure Vascular bundles

Primary structure of stem

Shipunov

BIOL 154.6


Other tissues Anatomy of stem

From SAM to primary structure Vascular bundles

Procambium to xylem and phloem

Outer layers of procambium form primary phloem Inner layers become primary xylem Sometimes outermost layers of procambium form pericycle (parenchyma cells) In some cases, inner layers of cor tex could form endoderm

Shipunov

BIOL 154.6


Other tissues Anatomy of stem

From SAM to primary structure Vascular bundles

Vascular bundle 1

Corn (Zea mays) mature stem cross-section showing single vascular bundle, Brightfield (LM в400)
Shipunov BIOL 154.6


Other tissues Anatomy of stem

From SAM to primary structure Vascular bundles

Vascular bundle 2

Wild Sunflower (Helianthus sp.) with nearly mature vascular bundle (LM в35)
Shipunov BIOL 154.6


Other tissues Anatomy of stem

From SAM to primary structure Vascular bundles

Origin of vascular bundles

Shipunov

BIOL 154.6


Other tissues Anatomy of stem

From SAM to primary structure Vascular bundles

Vascular bundles

Vascular bundles connect leaves and stems In many plants, they form ring on the cross-section of stem ("dicot" stem) Monocot stems usually have dispersed vascular bundles

Shipunov

BIOL 154.6


Other tissues Anatomy of stem

From SAM to primary structure Vascular bundles

Vascular bundles and leaf traces

Shipunov

BIOL 154.6


Other tissues Anatomy of stem

From SAM to primary structure Vascular bundles

Monocot stem

Corn (Zea mays) stem (LM в4)
Shipunov BIOL 154.6


Other tissues Anatomy of stem

From SAM to primary structure Vascular bundles

Primary Thickening Meristem (PTM)

PTM occurs only in "dicot" stems
Shipunov BIOL 154.6


Other tissues Anatomy of stem

From SAM to primary structure Vascular bundles

Steles 1

Stele is an overall configuration of primary vascular system of plant stem The most impor tant kinds of steles are: protostele, siphonostele, eustele and ataktostele*

Shipunov

BIOL 154.6


Other tissues Anatomy of stem

From SAM to primary structure Vascular bundles

Steles 2

(1) is protostele, (7) siphonostele (occurs in ferns), (8) eustele ("dicot" stem), (9) ataktostele (monocot stem)
Shipunov BIOL 154.6


Other tissues Anatomy of stem

From SAM to primary structure Vascular bundles

Summary

Absorbtion tissues take water from soil Secretory tissues extract different chemicals outside SAM produces protoderm and ground meristem, ground meristem differentiates into cortex and pith Procambium forms vascular bundles or vascular cylinder Outer layers of procambium transform into primary phloem, inner layers -- into primary xylem Monocot stem usually has dispersed vascular bundles (ataktostele)

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Appendix

For Fur ther Reading

For Fur ther Reading

Th. L. Rost, M. G. Barbour, C. R. Stocking, T. M. Murphy. Plant Biology. 2nd edition. Thomson Brooks/Cole, 2006. Chapters 4.3, 5.2 and 5.3.

Shipunov

BIOL 154.6