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Chapter 35 Plant Structure and Growth
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Chapter 35 Plant Structure and Growth. I. Two Systems A.Root System B.Shoot System.

Dec 29, 2015

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Erik Collins
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Page 1: Chapter 35 Plant Structure and Growth. I. Two Systems A.Root System B.Shoot System.

Chapter 35

Plant Structure and Growth

Page 2: Chapter 35 Plant Structure and Growth. I. Two Systems A.Root System B.Shoot System.

I. Two Systems

A. Root System

B. Shoot System

Page 3: Chapter 35 Plant Structure and Growth. I. Two Systems A.Root System B.Shoot System.

A. Root System

• Used for absorption of minerals and water

• Root hairs are used for most of the absorption

• Adventitious roots are found above ground for support

Page 4: Chapter 35 Plant Structure and Growth. I. Two Systems A.Root System B.Shoot System.

B. Shoot System

1. Stems- nodes are where the leaves attach- internodes are segments between nodes- axilliary buds are found in an angle between leaf and stem / can produce a branch- terminal buds are where growth is occurring- modified shoots: stolons, rhizomes, tubers, bulbs

2. Leaves- blade and petiole which attaches the leaf to node

Page 5: Chapter 35 Plant Structure and Growth. I. Two Systems A.Root System B.Shoot System.
Page 6: Chapter 35 Plant Structure and Growth. I. Two Systems A.Root System B.Shoot System.
Page 7: Chapter 35 Plant Structure and Growth. I. Two Systems A.Root System B.Shoot System.

II. 3 Tissue Types

Plant organs (leaves, stems, roots) are made of:

• Dermal• Vascular• Ground

Page 8: Chapter 35 Plant Structure and Growth. I. Two Systems A.Root System B.Shoot System.
Page 9: Chapter 35 Plant Structure and Growth. I. Two Systems A.Root System B.Shoot System.

A. Dermal Tissue

• Responsible for protection

• Epidermis

• Single layer of cells that make up the skin of the plant

Page 10: Chapter 35 Plant Structure and Growth. I. Two Systems A.Root System B.Shoot System.

B. Vascular Tissue

• Responsible for Transport of Materials• Made of xylem and phloem1. Xylem – carries water and minerals up

- tracheids are pitted, tapered, elongated cells dead at maturity, with lignified cell walls- vessel elements are pitted, squatty, wide, dead, and lignified and make up long tubes, form xylem vessels

Page 11: Chapter 35 Plant Structure and Growth. I. Two Systems A.Root System B.Shoot System.
Page 12: Chapter 35 Plant Structure and Growth. I. Two Systems A.Root System B.Shoot System.

B. Vascular Tissue

2. Phloem – carries glucose and hormones down from leaves

- sieve-tube members are alive at maturity and move sugars with the help of companion cells that load the sugar, separated by sieve plates

Page 13: Chapter 35 Plant Structure and Growth. I. Two Systems A.Root System B.Shoot System.
Page 14: Chapter 35 Plant Structure and Growth. I. Two Systems A.Root System B.Shoot System.

C. Ground Tissue

• This is a filler with diverse function from photosynthesis to storage to support

• Divided into the pith which is inside the vascular tissue, and the cortex with lies outside the vascular tissue

Page 15: Chapter 35 Plant Structure and Growth. I. Two Systems A.Root System B.Shoot System.

III. 3 Cell Types

The tissues we just went over are made up of:

• Paranchyma• Collenchyma

• Sclerenchyma

Page 16: Chapter 35 Plant Structure and Growth. I. Two Systems A.Root System B.Shoot System.

A. Paranchyma Cells

• “Typical” Plant Cell• Thin, flexible primary cell wall• No secondary cell wall• Large central vacuole• Least specialized• Most metabolic functions / photosynthesis and

starch storage in plants• All cells start here / embryonic “stem” cells• Retain ability to differentiate• Alive at maturity

Page 17: Chapter 35 Plant Structure and Growth. I. Two Systems A.Root System B.Shoot System.
Page 18: Chapter 35 Plant Structure and Growth. I. Two Systems A.Root System B.Shoot System.

B. Collenchyma Cells

• Thicker primary cell wall / unevenly thick

• Grouped in cylinders to provide support to young shoots

• Lack of secondary cell wall

• Living and flexible / don’t restrict growth

Page 19: Chapter 35 Plant Structure and Growth. I. Two Systems A.Root System B.Shoot System.
Page 20: Chapter 35 Plant Structure and Growth. I. Two Systems A.Root System B.Shoot System.

C. Sclerenchyma Cells

• Thick secondary walls filled with lignin• Rigid• Can not elongate• Dead at maturity• Make up vessel elements and tracheids• Fibers are long, slender, and tapered /

hemp• Sclereids are shorter with irregular shape /

nutshells

Page 21: Chapter 35 Plant Structure and Growth. I. Two Systems A.Root System B.Shoot System.
Page 22: Chapter 35 Plant Structure and Growth. I. Two Systems A.Root System B.Shoot System.

IV. Types of Meristems (Embryonic Tissue)

A. Apical Meristems allow for growth in length and are found at the tips of roots and buds

- They allow for primary growth (length)

B. Lateral Meristems allow for growth in girth called secondary growth

Page 23: Chapter 35 Plant Structure and Growth. I. Two Systems A.Root System B.Shoot System.
Page 24: Chapter 35 Plant Structure and Growth. I. Two Systems A.Root System B.Shoot System.

V. Primary Growth

A. Roots

B. Shoots

Page 25: Chapter 35 Plant Structure and Growth. I. Two Systems A.Root System B.Shoot System.

A. Roots

1. Root Cap covers the meristem and lubricates the soil

2. Zone of Cell Division which is where you’ll find the apical meristem, quiescent center and the three primary meristem: protoderm (dermal), procambium (VT, stele, runs down center), and ground meristem (ground)

3. Zone of Elongation is where the cells lengthen and push the root tip forward

4. Zone of Maturation is where cells complete differentiation and become functionally mature

Page 26: Chapter 35 Plant Structure and Growth. I. Two Systems A.Root System B.Shoot System.
Page 27: Chapter 35 Plant Structure and Growth. I. Two Systems A.Root System B.Shoot System.

A. Roots

4. Other Terms

Stele – arises from the procambium / vascular tissue develops here

Pericycle – outermost layer of stele

Endodermis – innermost layer of endodermis

Page 28: Chapter 35 Plant Structure and Growth. I. Two Systems A.Root System B.Shoot System.

Monocot Root

Page 29: Chapter 35 Plant Structure and Growth. I. Two Systems A.Root System B.Shoot System.

Dicot Root

Page 30: Chapter 35 Plant Structure and Growth. I. Two Systems A.Root System B.Shoot System.

B. Shoots• Dome shaped apical meristem still gives rise to

primary meristems: protoderm, procambium, and ground meristem

1. Stems- VT runs through stem in strands of vascular bundles instead of down the middle- Dicots have phloem facing out and xylem facing the pith and monocots have the bundles scattered throughout

2. Leaves- Stomata are holes in epidermis flanked by guard cells- Mesophyll is an area of ground tissue mostly made of paranchyma cells with columnar palisade parenchyma cells on top and spongy parenchyma cells on the bottom

Page 31: Chapter 35 Plant Structure and Growth. I. Two Systems A.Root System B.Shoot System.

Monocot Stem

Page 32: Chapter 35 Plant Structure and Growth. I. Two Systems A.Root System B.Shoot System.

Dicot Stem

Page 33: Chapter 35 Plant Structure and Growth. I. Two Systems A.Root System B.Shoot System.

Dicot Leaf

Page 34: Chapter 35 Plant Structure and Growth. I. Two Systems A.Root System B.Shoot System.

VI. Secondary Growth

• 2 types of lateral meristems function in secondary growth:

- The vascular cambium which creates secondary xylem (wood) and the secondary phloem

- The cork cambium which makes thick coverings replacing the epidermis

Page 35: Chapter 35 Plant Structure and Growth. I. Two Systems A.Root System B.Shoot System.
Page 36: Chapter 35 Plant Structure and Growth. I. Two Systems A.Root System B.Shoot System.

A. Stems1. Vascular Cambium

- produces secondary xylem in and secondary phloem out- forms between primary xylem and phloem- as time goes on layers of secondary xylem accumulate / the spring tracheids and vessel cells are large with thin walls and later they become thinner with thick walls- form rings of trees

Page 37: Chapter 35 Plant Structure and Growth. I. Two Systems A.Root System B.Shoot System.

A. Stems

2. Cork Cambium- early in secondary growth the epidermis falls off and CC makes new tissue- produces cork to the outside for protection and cork and CC are called the periderm- Bark is the periderm plus primary and secondary phloem- old phloem and cork are sloughed off through growth- heartwood, dark with no water / sapwood, carries water and is the secondary xylem

Page 38: Chapter 35 Plant Structure and Growth. I. Two Systems A.Root System B.Shoot System.
Page 39: Chapter 35 Plant Structure and Growth. I. Two Systems A.Root System B.Shoot System.
Page 40: Chapter 35 Plant Structure and Growth. I. Two Systems A.Root System B.Shoot System.

B. Roots

• Very similar to stems but only newest roots can take in water because the periderm is waterproof

Page 41: Chapter 35 Plant Structure and Growth. I. Two Systems A.Root System B.Shoot System.

VII. Mechanisms of Plant Growth

• Asymmetrical Cell Division creates guard cells and determines the top and bottom of the plant

• Plane is determined by preprophase bands

• Gradients effect positional information

• Homeotic Genes play a role (master genes)