Fall 2019

David Wm. Reed

ANATOMY AND MORPHOLOGY OF PLANT ORGANS

Organs

Tissue Systems

Tissues

Cell Types

Meristems

Monocots, Dicots and Gymnosperms

Roots, Stems, Leaves, Flowers, Fruit and Seeds

Katherine Esau and her authoritative text Plant Anatomy

1898-1997

“absolutely dominated the field of plant biology even at the age of 99”

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REFERENCES USED IN ANATOMY AND MORPHOLOGY SECTION

Anzai, T. 1975. Two phases in adventitious root formation in Phaseolus mungo hypocotyl cuttings. J. Exp. Bot.

26:580-588.

Argles, G.K. 1959. Root formation and root development in stem cuttings: A re-examination of certain fundamental

aspects. Ann. Appl. Bot. 47:626-628.

Cameron, R.J. and G.V. Thomson. 1969. The vegetative propagation of Pinus radiata: Root initials in cuttings. Bot.

Gaz. 130:242-251.

Clowes, F.A. 1961. Apical Meristems. Bot. Monogr. Vol. 2, Oxford, Blackwell.

Davies, F.T., J.E. Lazarte and J.N. Joiner. 1982. Initiation and development of roots in juvenile and mature Ficus

leaf bud cuttings. Amer. J. Bot. 69:804-811.

Dermen, H. 1960. Nature of Plant Sports. Amer. Hort. Mag. 39(3):123-173

Dore, J. 1965. Physiology of regeneration in cormophytes. Encycl. Plant Physiol 15:1-91.

Esau, K. 1960. Anatomy of Seed Plants, John Wiley & Sons, Inc., NY

Esau, K. 1965. Plant Anatomy, John Wiley & Sons, Inc., NY

Ginzburg, C. 1967. Organization of the adventitious root apex in Tamarix aphylla. Amer. J. Bot. 54:4-8.

Girouard, R. M. 1967. Initiation and development of adventitious roots in stem cuttings of Hedera helix. Can. J. Bot.

45:1877-1884.

Hartman, H.T., D.E. Kester and F.T. Davies, Jr. 1990. Plant Propagation - Principles and Practices. Prentice Hall,

Inc., Englewood Cliffs, NJ.

Leopold, A.C. and P.E. Kriedemann. 1964. Plant Growth and Development. McGraw-Hill, Inc., NY.

Naylor, E.E. and B. Johnson. 1937. A histological study of vegetative reproduction in Saintpaulia ionantha. Amer. J.

Bot. 24:673-678.

Romberger, J.A. 1963. Meristems, Growth and Development in Woody Plants, USDA Technical Bulletin No. 1293.

Sachs, 1965, Annual Rev. Plant Physiol. 16:73-96.

Siegler, E.A. and J.J. Bowman. 1939. Anatomical studies of root and shoot primordia in 1-year apple adventitious

roots. J. Agr. Res. 58:795-803.

Smith, D.R. and T.A. Thorpe. 1975. Root initiation in cuttings of Pinus radiata seedlings. I. Developmental

sequence. J. Exp. Bot 26:184-192.

Stewart, R.N. and H. Dermen. 1979. Ontogeny in monocotyledons as revealed by studies of the developmental

anatomy of periclinal chloroplast chimeras. Amer. J. Bot. 66(1):47-58.

Strangler, B.B. 1955. Origin and development of roots in stem cuttings of chrysanthemum, carnation and rose. N.Y.

Ag. Exp. Sta., Mem 342, pp.3-24.

Tilney-Bassett, R.A.E. 1986. Plant Chimeras. Edward Arnold Ltd., Baltimore, MD.

Walker, R.I. 1940. Regeneration in the scale leaf of Lilium candidum and L. longiflorum Amer. J. Bot. 27:114-117.

Wardlow, C.W. 1957. On the organization and reactivity of the shoot apex in vascular plants. Amer. J. Bot. 44:176-

185.

Wareing, P.F. and I.D.J. Philips. 1981. Growth and Differentiation in Plants, Pergamon Press, NY

Wilkenson, R.E. 1966. Adventitious shoots on salt cedar roots. Bot. Gaz. 127:103-104.

Yarborough, J.A. 1936. Regeneration in the foliage leaf of Sedum. Amer. J. Bot. 23:303-307.

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ORGANS AND TISSUE SYSTEMS

Plants are composed of 3 vegetative and 1 reproductive organ.

Three tissue systems comprise each organ and are contiguous between each of the three organs.

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PLANT ORGANS, TISSUE SYSTEMS, TISSUES AND CELL TYPES

3 TISSUE SYSTEMS OCCUR IN PLANTS

1) Dermal Tissue System

Function: Protection from the environment and water loss.

Tissues:

a) epidermis - single layer of cells on primary (herbaceous) plant parts.

b) periderm or bark - a corky tissue that replaces epidermis on secondary (woody) plant

parts.

2) Vascular Tissue System

Function: Conduction of water, nutrients, sugars and hormones throughout the plant.

Tissues:

a) xylem - conducts water and nutrients up roots, stems and leaves.

P4F3 xylem blowing steam.MOV

b) phloem - conducts water, sugar, hormones, etc. primarily up and down roots, stems and

leaves, from source to sink of greatest need.

3) Ground or Fundamental Tissue System

Function: Storage, support, filler tissue and site of photosynthesis.

Tissues:

a) cortex - outer region of stems and roots.

b) pith - center of stems.

c) mesophyll - middle of leaves and flower petals

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CELL TYPES

1) parenchyma

-thin, non-lignified primary

cell walls

-filler, storage, protection,

photosynthesis

-examples: flesh of potato,

lettuce

isodiametric

2) collenchyma

-unevenly thickened, non-

lignified primary cell walls

-support in growing tissues

-example: strings in celery longer than wide

3) sclerenchyma

2 Types

a) fiber

b) sclereid or

stone cell

-evenly thickened, lignified

(tough) secondary cell

walls

-support in mature tissue

-examples:

fiber -bamboo cane

sclereid - seed coat

stone cell -pear fruit

fiber

sclereid stone cell

parenchyma in mesophyll collenchyma stands in celery stalk

water storage adds rigidity to petiole

(www.flickr.com/photos/pauliedan/3892339473)

sclerenchyma in hard seed coat of Lupinus (Esau Fig. 22.3)

Makes seed coat impermeable to water

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MERISTEMS AND GROWTH

Primary Growth - growth in length that gives rise to primary (herbaceous) tissues called the

primary plant body.

2 -Types

apical meristem or apex - the growing points located at the tips of stems and roots

intercalary meristem - the growth region at the base of grass leaves that causes

leaves to elongate.

Secondary Growth - growth in width or diameter that gives rise to secondary (woody

or corky) tissues called the secondary plant body.

lateral meristem - meristematic regions along the sides of stems and roots.

2 Types

vascular cambium or cambium - gives rise to secondary xylem (wood) on the

inside and phloem on the outside.

cork cambium or phellogen - gives rise to the periderm (bark).

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MORPHOLOGY OF APICES

Shoot and Root Apex (Fig. 3.2 from Esau 1960)

Flower Apex

(Fig. 2.20 from Wareing and Philips 1981)

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ORGANIZATION OF APICAL MERISTEMS

Geometrical Organization or Tunica-Corpus

Concept - Shoot

(Esau 1965, Romberger 1963)

1) tunica (mantle)

– outer covering of apex

– only anticlinal divisions

2) corpus (core)

- inner region of apex

- anticlinal and periclinal divisions

Morphological Organization - Shoot

Wardlaw (AJB 44:176 1957)

1) distal - outer covering (like tunica)

2) sub-distal - region of physiological

inception of growth centers

3) organogenic - region of 1st visual

appearance of growth centers

4) subapical - region of growth of organs

5) region of maturation

Sachs (ARPP 16:73 1965)

1, 2 & 3) - apical region, where

differentiation/organogenisis occurs

4 & 5) - sub-apical region - where elongation

occurs

Cytological and Histological Organization -

Shoot

Buvat (see Esau 1965, Romberger 1963)

1) distal zone - waiting or promeristem

2) peripheral zone - initiating ring or

eumeristem

3) inner zone - medullary or rib meristem

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MONOCOTS, DICOTS AND GYMNOSPERMS

DISTINGUISHING CHARACTERISTIC

DIVISION Spermatophytes (Spermatophyta-seed bearing plants)

SUBDIVISION

Angiosperms

(Angiospermae)

(flowering plants with seeds enclosed)

Gymnosperms

(Gymnospermae)

(naked seeds)

CLASS

Monocots

(Monocotyledoneae)

(1 cotyledon)

Dicots

(Dicotyledoneae)

(2 cotyledons)

Seeds

1 cotyledon; endosperm

often present

2 cotyledons;

endosperm often

lacking

1 to many cotyledons; no

endosperm; female

gametophyte tissue present

Flowers Flower parts in

multiples of 3

Flower parts in

multiples of 4 or 5 No true flowers

Leaves

Linear; leaf base or

petiole (if present)

sheathing; parallel

venation

Broad; petiole

present; net venation Needle-like or scale-like

Vascular

System of Stem

Scattered vascular

bundles; no cambium or

secondary growth

Ring of vascular

bundles in primary

growth; cambium

present in secondary

growth

Ring of vascular bundles in

primary growth; cambium

present in secondary

growth

Growth Habit

Herbaceous to wood-

like (ex. palm), but no

true wood (secondary

xylem)

Herbaceous or

woody Herbaceous or woody

Morphology

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STEM ANATOMY

Dicot or Gymnosperm – Primary Growth

(Fig. 16.1 from Esau 1960)

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STEM ANATOMY

Dicot or Gymnosperm – Secondary Growth

(Plate 28 from Esau 1965)

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STEM ANATOMY

Monocot – Primary Growth

(Plate 58 from Esau 1965, Fig. 17.8 from Esau 1960)

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ROOT ANATOMY

Dicot, Gymnosperm or Monocot - Primary Growth

(Plate 84 & 86 from Esau 1965)

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ROOT ANATOMY

Dicot, Gymnosperm or Monocot – Secondary Growth

A woody dicot or gymnosperm root in secondary growth looks very similar to a stem in

secondary growth.

(Fig.15.4 from Esau 1960)

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LEAF ANATOMY

Dicot

(Plate 73 from Esau 1965)

Monocot

(Similar to dicot, except no palisade, mesophyll is all spongy parenchyma)

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LEAF ANATOMY

Gymnosperm

(Plate 78 from Esau 1965)

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LEAF PARTS - FUNCTION

STOMA

An open aperture surrounded by 2 guard cells.

a) open when guard cells are turgid

b) closed when guard cells are flaccid

Diurnal Cycle

a) open in day

b) closed at night

c) except CAM plants, just opposite (open night, closed day)

Designed for gas exchange

a) CO2 in and 02 out for photosynthesis

b) CO2 out and 02 in for respiration

c) H20 out during transpiration

Usually more frequent on epidermis of lower leaf surface

MESOPHYLL

Palisade parenchyma

- contains 70-80% of the chloroplasts in the leaf

- specialized for photosynthesis because it contains a large number of chloroplasts and it occurs

towards the adaxial side of leaf

- thinner on a sun grown leaf

Spongy mesophyll

- contains large air spaces

- specialized for gas exchange -because of the large air space and more stomata occur on the

epidermis of abaxial leaf surface

- thicker on a shade grown leaf

ABSCISSION ZONE

Leaves of deciduous plants form an abscission zone in a discrete region at the base of the petiole.

The surface is sealed and suberized over before the leaf falls off.

(Fig. 18.10 from Esau 1960)

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SUMMARY MATRIX OF ANATOMY

MONOCOT DICOT GYMNOSPERM

STEM

PRIMARY

(herbaceous)

GROWTH

SECONDARY

(woody)

GROWTH

none

ROOT

PRIMARY

(herbaceous)

GROWTH

SECONDARY

(woody)

GROWTH

none

LEAF

PRIMARY

(herbaceous)

GROWTH

SECONDARY

(woody)

GROWTH

none

none

none

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FLOWER

FLOWER - A determinate shoot with leaves highly modified into reproductive parts

FLOWER STRUCTURE

FLOWER TYPES BASED ON PARTS PRESENT

complete - contains all floral parts, i.e. sepals, petals, stamens and pistils

incomplete - lacks one or more of the floral parts

perfect - contains both pistils and stamens (may or may not have sepals or petals)

imperfect - lacks either pistils or stamens (may or may not have sepals or petals)

pistillate - contains only pistils (may or may not have sepals or petals)

staminate - contains only stamens (may or may not have sepals or petals)

sterile - both stamens and pistils are absent, or are non-functional

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PLANT TYPES BASED ON FLOWER TYPES PRESENT

monoecious - both staminate and pistillate flowers occur on the same plant.

Example corn, cucumber

From aggie-horticulture.tamu.edu

dioecious - staminate and pistillate flowers occur on separate plants.

Example holly, persimmon

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FRUIT

fruit - a ripened or matured ovary and its contents plus any accessory tissues.

pericarp - the fruit wall, which developed from the ovary wall

Composed of 3 layers:

1) exocarp - outer layer of the pericarp

2) mesocarp - middle layer of the pericarp

3) endocarp - inner layer of the pericarp.

FRUIT STRUCTURE

Example of a dry fruit Example of a fleshy fruit

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SEED

seed - a ripened or matured ovule consisting of an embryo with associated stored food

and covered by a testa.

STRUCTURE

TESTA STRUCTURE AND FUNCTION (Fig. 22.3 from Esau 1960, Fig. 10-10 from Leopold and Kriedemann 1964)