Anatomy, Morphology, & Growth Anatomy, Morphology, & Growth of Angiosperms – Ch. 5-8of Angiosperms – Ch. 5-8

Two plant groups: monocots & dicots

Cells

Tissues

Organs

Systems

Muscle cell

Muscle tissue

Heart

Circulatory system

The Plant Cell

Fig 7.8

5 Differentiated Plant Cell Categories

1. Parenchyma2. Collenchyma3. Schlerenchyma4. Water-conducting cells of the xylem5. Sugar-conducting cells of the phloem

1. Parenchyma

• thin and flexible cell walls

2. Collenchyma

• Usually grouped in strands to support young parts of plants without restraining growth

• Flexible, elongate with growing shoots

3. Schlerenchyma

• May be dead at functional maturity – ??? • cell walls left behind as skeleton

4. Water conducting cells of the xylem:

• 2 types: tracheids & vessel elements

Tracheids

• Water flows from cell to cell (laterally) through pits in cell wall

• Support function

Vessel Elements

• End walls are perforated for free flow of water• More efficient as water conductors than tracheids

Fig 35.9

5. Sugar-conducting cells of the phloem

Sieve-tube members:

• Lack a nucleus, ribosomes, vacuole• Cells separated by perforated sieve plates –

allow sugar movement

Fig 35.9

Three main tissues: Dermal,

Vascular, Ground

Fig 35.8

1. Dermal tissue or epidermis

• Root hairs are specialized epidermal extensions• Secretes waxy cuticle of the leaf

2. Ground Tissue

• fills the space between dermal and vascular tissue systems.

• Diverse functions:

pith

cortexIn dicots:

3. Vascular Tissue

• function in transport between roots & shoots, and structural support of plant– Xylem:

– Phloem: Food transported to roots & non-photosynthetic parts such as the flowers

Growth & Development

http://www.cneccc.edu.hk/subjects/bio/album/Chapter20/PLANT_GROWTH.html

• Development =

Three processes of development:

1. Growth =

2. Cellular differentiation = generation of different cell types

3. Morphogenesis – creation of body form & organization.

1. Growth

• Cell division no expansion

• = due to water uptake in the vacuole

Growth

Fig 35.24

Cell division

• Occurs in only in meristems!

Meristems• =

• Two types of meristems:1. Apical meristem –

2. Lateral meristems – extend lengthwise along the axis of the stem & roots. Responsible for growth in girth in older parts of the plant (called secondary growth). Exist only in perennials

Fig 35.10

Arrangement of Primary Tissues in Roots1. Epidermis –

2. Stele –

3. Ground tissue – mostly parenchyma cells of the cortex – area between the stele & epidermis; stores food & takes up minerals.

• Endodermis – single cell layer between cortex & stele. Selective barrier for uptake of soil solution contents into vascular system.

Fig 35.13

Epidermis

Cortex

Endodermis

Stelexylem

phloem

Eudicot/Gymnosperm root cross section

Primary Growth of Shoots

• Bud = cluster of leaf primordia created by meristem. No internodes

• Lateral branches arise from axillary buds

Fig 35.15

Primary tissue arrangement of stems

– Ground tissue = pith & cortex

Fig 35.16

pith

cortex

epidermis

phloem

xylem

Schlerenchyma cells

Eudicot/Gymnosperm stem cross section

Tissue arrangement of leaves

• 3 parts:1. Upper & lower epidermis – tightly interlocked cells,

secrete waxy cuticle. Contains stomata flanked by guard cells

2. Vascular tissue –

3. Mesophyll – ground tissue between upper & lower epidermis

Fig 35.17

Secondary Growth

• Two lateral meristems:1. Vascular cambium – produces secondary

xylem (= wood) & phloem2. Cork cambium – replaces the epidermis with

cork: tough, thick cover for stems, roots.

Secondary growth of stems• Vascular cambium – layer of cells between

primary xylem & primary phloem. Puts on successive layers of secondary phloem to outside & secondary xylem to inside =====> stem widens

• Wood = accumulation of secondary xylem. Dead at maturity, contains lignin

What is bark?• “bark” =

• Cork continually sloughs off

Fig 35.18

Fig 35.20

Three types of life cycles:

1. Annual –

2. Biennial – complete life cycle in two years (first year = vegetative, second year = reproductive). Some need a cold winter period to initiate flowering from vegetative state. Ex. carrots

3. Perennial – live year after year, do not die after reproduction. Examples: trees, shrubs, some grasses. Causes of death = fire, disease