Bi 151 Plant Morpho-anatomy Lecture 1. What are plants??? Kingdom Plantae (plants) 6/26/2014. What are some structural features of plants?

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1 Bi 151 Plant Morpho-anatomy Lecture 1 What are plants??? Plants: General Structural Features Jan Lorie M. Robil, M.Sc. Kingdom Plantae (plants) 1. Multicellular 2. Autotrophs (chloroplasts) 3. Cellulose in cell walls 4. Eukaryotic (true nucleus; DNA enclosed by a membrane) What are some structural features of plants? 1. Cellulosic cell walls 2. Chloroplasts 3. Appearance a. Can include stems, leaves, and roots b. Some lack true stems, leaves, and roots 1

2 Flowering Plants ANGIOSPERMS Magnoliids Monocots Eudicots White Champaca Waling-waling Jade vine Shoot and Root systems above or below ground no clear demarcation morphology and anatomy are somewhat continuous adventitious parts Shoot system Basic Morphology Leaf Stem Leaves Leaves-modifications Jatropha curcas Casuarina equisetifolia Alamanda cathartica Schefflera odorata 2

3 Leaf shape A. Elliptic B. Obovate C. Ovate D. Lanceolate E. Reniform F. Cordate G. Trullate H. Deltoid I. Rhomboid J. Amplexicaul K. Perfoliate L. Connate-perfoliate M. Ensiform N. Ligulate O. Sagittate P. Plated Leaf shape Psidium guajava Bauhinia purpurea Citrus sp. Hibiscus sp. Leaf venation acrodromous venation Leaf venation parallel venation Eudicot Miconia sp. Monocot Bambusa sp. Stem Stem - modifications tubers stolon rhizome tendril 3

4 Roots Plant Cells and Tissues An Evolutionary Perspective Plants are structurally complex All the cells of a plant are genetically identical But the information is expressed in different ways in different places at different times in a synchronized fashion Plants Arose from the Green Algae Silurian Period Over 400 Million Years Ago... but plants arose from structurally simple ancestors Evidence That Plants Arose from the Green Algae Pigmentation 4

Evidence That Plants Arose from the Green

walls walls Starch stored in the plastid

means of a phragmoplast walls Starch stored

structural complexity of plants evolved in

5 Evidence That Plants Arose from the Green Algae Pigmentation Cellulose in their cell walls Evidence That Plants Arose from the Green Algae Pigmentation Cellulose in their cell walls Starch stored in the plastid Some green algae undergo cell division by means of a phragmoplast Evidence That Plants Arose from the Green Algae Pigmentation Cellulose in their cell walls Starch stored in the plastid Some green algae undergo cell division by means of a phragmoplast The structural complexity of plants evolved in response to the challenges of life on land 5

Plants can be considered simply as a group of the green algae that have become adapted for life on

Water and Minerals Transport of Photosynthate Fertilization Dehydration Support Transport of Water and

Phloem Tissue Reproductive organs Ground Tissue System Vascular plants are made up of three tissue

6 Plants can be considered simply as a group of the green algae that have become adapted for life on land. Challenges for Colonizing the Land Solutions (Adaptations) Dehydration Support Transport of Water and Minerals Transport of Photosynthate Fertilization Dehydration Support Transport of Water and Minerals Transport of Photosynthate Fertilization Dermal tissue; Cuticle Secondary Walls Xylem Tissue Phloem Tissue Reproductive organs Ground Tissue System Vascular plants are made up of three tissue systems which are represented in each plant organ. Includes cells and tissues like those found in the green algae 6

Dermal Tissue System Vascular Tissue System found in all

Are tissues that transport substances long distances in

Cells and Tissues of the Ground Tissue System Green

Parenchyma Parenchyma cells are living, undifferentiated

Typically, parenchyma cells are totipotent.

7 Dermal Tissue System Vascular Tissue System found in all plants Dermal tissue of a hornwort, a non-vascular plant Are tissues that transport substances long distances in a plant. Cells and Tissues of the Ground Tissue System Green Algae All Plants Parenchyma Collenchyma Sclerenchyma Parenchyma Parenchyma cells are living, undifferentiated plant cells usually lacking a secondary cell wall. Typically, parenchyma cells are totipotent. Each cell retains the ability to grow into a whole plant. This makes genetic engineering much easier with plants than with animals. 7

8 Parenchyma Tissue Function Growth/Wound Healing/Reproduction Parenchyma Tissue Functions Growth/Wound Healing/Reproduction Photosynthesis Parenchyma Tissue Functions Growth/Wound Healing/Reproduction Photosynthesis Storage 8

Collenchyma Tissue Is a simple tissue consisting only of

thickened primary walls. They never have secondary walls.

Collenchyma Tissue Support in herbaceous tissues 400x Collenchyma

rigidity to the plant Sclerenchyma Tissue Sclerenchyma (hard)

Sclerenchyma lends integrity to plant tissues, and/or they serve

9 Collenchyma Tissue Is a simple tissue consisting only of collenchyma cells Collenchyma cells are living cells with thickened primary walls. They never have secondary walls. Collenchyma Tissue Support in herbaceous tissues Flexebility Collenchyma Tissue Support in herbaceous tissues 400x Collenchyma acts in opposition to turgor pressure, And, together, they lend rigidity to the plant Sclerenchyma Tissue Sclerenchyma (hard) cells develop a secondary wall, and are not involved in transport. Sclerenchyma lends integrity to plant tissues, and/or they serve to support and protect the plant. There are two types of sclerenchyma cells. Fibers Sclereids 9

Fibers Sclereids Brachysclereids Unbranched Sclereids

Includes: Parenchyma cells and tissue Collenchyma cells

exclusively found in the ground tissue Dermal Tissue

Dermal Tissue System Basal Cells of the Epidermis of the

10 Fibers Sclereids Brachysclereids Unbranched Sclereids Branched Sclereids (astrosclereids) Ground Tissue System Includes: Parenchyma cells and tissue Collenchyma cells and tissue Sclerenchyma cells and tissue These are not exclusively found in the ground tissue Dermal Tissue System In herbaceous plants, an epidermis makes up the dermal tissue system. Cell types of the epidermis Basal Cells of the Epidermis Dermal Tissue System Basal Cells of the Epidermis of the Shoot As the cuticle is air-tight as well as water-proof it must be perforated to allow for gas exchange. 10

If these openings are bounded by guard cells then these are called

In the shoot, the epidermis includes basal cells and guard cells Dermal

Periderms include cork which functions like the epidermis in retaining

The word cell was first used in a biological context in 1665 by Robert

Cork Tissue is Water-proof Dermal Tissue System Tissues and structures

11 If these openings are bounded by guard cells then these are called stomata. Dermal Tissue System Herbaceous plants have an epidermis. In the shoot, the epidermis includes basal cells and guard cells Dermal Tissue System Mature woody plant the epidermis is replaced by a periderm. Periderms include cork which functions like the epidermis in retaining water. The word cell was first used in a biological context in 1665 by Robert Hooke to describe the units that make up the tissue of a wine cork. Cork Tissue is Water-proof Dermal Tissue System Tissues and structures Herbaceous growth (primary) Epidermis (including basal cells and guard cells) Cuticle (cutin) Wood growth (secondary) Periderm with cork tissue Suberin Suberin 11

12 Green Algae All Plants Vascular tissue is necessary for a plant to become tall. Vascular plants have cells with secondary walls that include lignin But why not simply remain short? The Vascular Tissue System includes two types of tissues. Because of competition for light. Xylem Phloem 12

Vascular Tissue System complex tissues they are made up of more than

Simple tissues are made of one cell type such as parenchyma,

Xylem Moves water and minerals up the plant and provides support to

Phloem Moves photosynthate (usually sucrose) around the plant

response to the unique challenges of life on land relating to water

The evolution of phloem is not specific to the challenges of life on

13 Vascular Tissue System complex tissues they are made up of more than one cell type. Simple tissues are made of one cell type such as parenchyma, collenchyma and sclerenchyma tissues. Xylem Moves water and minerals up the plant and provides support to the plant. Phloem Moves photosynthate (usually sucrose) around the plant Evolution of Xylem and Phloem The evolution of xylem is a direct response to the unique challenges of life on land relating to water transport and support. The evolution of phloem is not specific to the challenges of life on land, but was simply a response to the challenge of becoming a large photo-autotroph. MacArthur Highway through Dau, Mabalacat, Pampanga Province, Luzon Island, Philippines Large photo-autotrophs invariably need to fuel a significant amount of non-photosynthetic tissue. 13

Xylem Xylem is a complex tissue that includes tracheary elements Tracheary elements are dead at maturity and have

The pressure inside tracheary elements is less than the ambient pressure and the secondary walls prevent the

Cohesion-Tension Theory Water is pulled up the tracheary elements, because water molecules stick together

Secondary walls keep the tracheary elements from collapsing help support the plant forms pits (holes) in the wall

14 Xylem Xylem is a complex tissue that includes tracheary elements Tracheary elements are dead at maturity and have always have a secondary wall. Water moves through these cells by mass flow. The pressure inside tracheary elements is less than the ambient pressure and the secondary walls prevent the cells from collapsing. Cohesion-Tension Theory Water is pulled up the tracheary elements, because water molecules stick together (cohere) via hydrogen bonds adhesion of water molecules to inner cell wall surface Role of Secondary Walls Secondary walls keep the tracheary elements from collapsing help support the plant forms pits (holes) in the wall Vessel elements in an elongating plant stem Tracheary Elements Two types Vessels Tracheids both have pits (holes) but only vessels have perforations A perforation is an area between tracheary elements where both the primary and secondary wall has been removed. 14

Vessels Vessels have independently evolved in six different plant groups.

Cells (Conifers) Sieve-Tube Elements (Angiosperms) Sieve-Tube Elements made up of sieve-tube members have sieve plates and are

albuminous cells Vascular Tissue System Xylem Always includes tracheary elements Tracheids and/or vessel elements May have

15 Vessels Vessels have independently evolved in six different plant groups. Flowering plants have them (Angiosperms) Conifers Don t (Gymnosperms) Phloem a complex tissue that includes sieve elements Sieve Cells (Conifers) Sieve-Tube Elements (Angiosperms) Sieve-Tube Elements made up of sieve-tube members have sieve plates and are associated with companion cells Gymnosperms have a different type of sieve element called a sieve cell - Associated with albuminous cells Vascular Tissue System Xylem Always includes tracheary elements Tracheids and/or vessel elements May have Parenchyma Vascular Tissue System Phloem Always has sieve elements If sieve-tube members then also companion cells If sieve cells then also albuminous cells May also have Parenchyma cells Fibers Fibers 15

Plant Anatomy: roots, stems and leaves

Plant Anatomy: roots, stems and leaves The plant body has a hierarchy of organs, tissues and cells Plants, like animals, have organs composed of different tissues, which are composed of cells. Tissue is