Chapter 1: Introduction to Plant Anatomy

• Plants have internal structures that vary in similarities and differences

• The study of the internal structure of plants is called anatomy

• Anatomy helps understand the different types of tissues in plants

Chapter 2: Meristematic Tissues

• Meristematic tissues undergo active cell division

• Meristems are specialized regions where meristematic tissues are present

• Primary meristems help in the development of the primary plant body

  • Apical meristem is located at the tips of roots and shoots

  • Intercalary meristem occurs between mature tissues

• Secondary meristems appear later in a plant's life and produce woody axis and secondary tissues

Chapter 3: Permanent Tissues

• Permanent tissues do not undergo cell division

• Simple permanent tissues are composed of cells that are similar in structure and function

• Complex permanent tissues are composed of different types of cells

• Xylem and phloem are examples of complex permanent tissues

Chapter 4: Xylem

• Xylem conducts water and minerals from roots to stems and leaves

• Xylem consists of tracheids, vessels, xylem fibers, and xylem parenchyma

• Tracheids are elongated, lignified cells without protoplasm

• Vessels are long, tube-like structures composed of vessel members

• Xylem fibers have thickened walls and obliterated central lumens

• Xylem parenchyma cells store food material and are produced from vascular cambium

Chapter 5: Primary Xylem

• Primary xylem is formed from meristematic tissues

• Protoxylem is the first-formed primary xylem, while metaxylem is formed later

• Indarch arrangement in stems has protoxylem towards the center and metaxylem towards the periphery

• Exarch arrangement in roots has protoxylem towards the periphery and metaxylem towards the center

Chapter 6: Phloem

• Phloem transports food materials from leaves to other parts of the plant

• Phloem consists of sieve-tube elements, companion cells, phloem parenchyma, and phloem fibers

• Sieve-tube elements are tube-like structures with perforated end walls

• Companion cells are parenchyma cells associated with sieve-tube elements

• Phloem parenchyma stores food material and other substances

• Phloem fibers provide mechanical support and are made up of sclerenchyma cells

Chapter 7: Simple Permanent Tissues

• Simple permanent tissues include parenchyma, collenchyma, and sclerenchyma

• Parenchyma is the most common ground tissue and functions in photosynthesis, storage, and secretion

• Collenchyma provides mechanical support to growing parts of a plant

• Sclerenchyma cells have thick walls and provide mechanical support

Chapter 8: Conclusion

• Permanent tissues are essential for the survival of plants

• Simple permanent tissues have cells that are similar in structure and function

• Complex permanent tissues are composed of different types of cells

Chapter 1: Sclerenchyma Tissue

• Sclerenchyma is a type of simple permanent tissue

• Consists of long, narrow cells with thick lignified cell walls

• Provides stiffness and mechanical support to plant organs

• Two types: fibers and sclereids

  • Fibers are narrow, elongated, thick-walled cells with pointed ends

  • Sclereids are short, thick-walled cells, generally spherical, oval, or cylindrical in shape

  • Fibers occur in groups in various parts of the plant

  • Sclereids occur in the hard covering of seeds, shells of nuts, and fruits like guava and pears

Chapter 2: Simple Permanent Tissues

• Simple permanent tissues provide protection, storage, support, and strength to the plant

• Plant tissue systems can be classified into three types:

  • Epidermal tissue system: forms the outermost covering of the plant body

  • Ground or fundamental tissue system: composed of parenchyma cells found in the cortex, pericycle, pith, and medullary rays

  • Vascular or conducting tissue system: composed of xylem and phloem, which form vascular bundles

Chapter 3: Epidermal Tissue System

• Forms the outermost covering of the plant body

• Consists of epidermal cells, stomata, and epidermal appendages (trichomes and hairs)

• Epidermal cells are parenchyma tissue with a large vacuole and lined with a small amount of cytoplasm

• Epidermis is coated with a thick and waxy layer called the cuticle to prevent water loss

• Stomata regulate transpiration and gaseous exchange, composed of two bean-shaped guard cells

• Subsidiary cells are specialized epidermal cells associated with guard cells

• Root hairs are unicellular elongations of epidermal cells that absorb water and minerals

• Trichomes are epidermal hairs on the stem, may be branched, unbranched, soft, or stiff, and prevent water loss

Chapter 4: Ground Tissue System

• Composed of parenchyma cells found in the cortex, pericycle, pith, and medullary rays

• Cortex is formed of thin-walled parenchyma cells and stores food material

• Pericycle is a few layers of thick-walled parenchyma cells and initiates lateral roots and vascular cambium

• Pith is the central region of the stem, composed of parenchyma cells

Chapter 5: Vascular Tissue System

• Composed of xylem and phloem, which form vascular bundles

• Cambium is present in dicotyledonous plants, allowing for secondary growth

• Vascular bundles can be open or closed depending on the presence of cambium

• Radial arrangement of xylem and phloem in roots, conjoint arrangement in stem and leaves

• Xylem and phloem are situated at the same radius in conjoint vascular bundles

• Cambium is present in conjoint open arrangement, absent in conjoint closed arrangement

Chapter 6: Anatomy of Dicot Root

• Epidermis is the outermost layer, followed by cortex and endodermis

• Endodermis has suberin deposits called Kasparian strips

• Pericycle is a few layers of thick-walled parenchyma cells and initiates lateral roots and vascular cambium

• Xylem and phloem patches are present, cambium ring forms between them

• Conjunctive tissue is specialized for water storage and located inside the endodermis

• Vascular bundles and pith form the stele

Chapter 7: Anatomy of Monocot Root

• Similar to dicot root in structure, but with some differences

• Epidermis, cortex, endodermis, pericycle, vascular bundle, and pith are present

• Monocot root can have many xylem bundles, well-developed pith

• Dicot and monocot roots differ in the number of xylem bundles, size of pith and cortex, and ability for secondary growth

Chapter 8: Anatomy of Stem in Dicot and Monocot Plants

• Dicot stem has epidermis, cortex, and stele

• Epidermis consists of closely packed cells with a cuticle, stomata, and trichomes

• Cortex stores food material and consists of hypodermis, cortical layers, and endodermis

• Stele contains vascular bundles

• Monocot stem has similar regions but can have many xylem bundles and a well-developed pith

Composition of the Dicot Stem

• The last region of a dicot stem is composed of the pericycle, vascular bundles, and pith.

• The pericycle is made up of starch-containing parenchyma cells and is located on the inner side of the endodermis above the phloem cells.

• The vascular bundles are arranged in a ring on the inside of the pericycle and consist of xylem and phloem.

• Layers of parenchyma cells called medullary rays are present between the vascular bundles.

• The pith is located in the central region of the stem and is composed of rounded parenchyma cells with intercellular spaces.

Comparison of Dicot and Monocot Stems

• The hypodermis of a monocot stem is composed of sclerenchyma cells, while in a dicot stem, it is composed of collenchyma cells.

• Monocot stems have scattered vascular bundles arranged in a conjoint and closed manner.

• Water-containing cavities are present within the vascular bundles of monocot stems.

• In contrast, dicot stems have vascular bundles arranged in a ring as conjoint and open.

• Monocot stems have a bundle sheath and parenchyma ground tissue surrounding each vascular bundle.

• The vascular bundles on the periphery of monocot stems are smaller compared to those in the center.

Structure of a Dicot Leaf

• A dicot leaf has three main parts: epidermis, mesophyll, and the vascular system.

• The epidermis covers the upper and lower surfaces of the leaf and is coated with a cuticle.

• The adaxial epidermis covers the upper surface, while the abaxial epidermis covers the lower surface.

• The abaxial epidermis usually has more stomata compared to the adaxial epidermis.

• The mesophyll is located between the upper and lower epidermis and contains chloroplasts for photosynthesis.

• The mesophyll is differentiated into palisade parenchyma (near the adaxial epidermis) and spongy parenchyma (extends up to the abaxial epidermis).

• The vascular system consists of vascular bundles found in the veins and midrib of the leaf.

• Vascular bundles are irregularly scattered in the mesophyll due to reticulate venation.

Structure of a Monocot Leaf

• A monocot leaf is isobilateral, meaning it is identical on both sides and shows parallel venation.

• Stomata are present on both surfaces of the epidermis in a monocot leaf.

• Palisade cells are not differentiated into palisade and spongy parenchyma in a monocot leaf.

• Vascular bundles in a monocot leaf are arranged in a parallel manner in the mesophyll.

• Monocot leaves, such as grasses, have bulliform cells in the upper epidermis that help regulate water loss.

Secondary Growth in Stems

• Secondary growth occurs after primary growth and leads to the formation of the woody axis or an increase in stem girth.

• Secondary growth in stems is due to the activity of secondary meristems, such as the vascular cambium and cork cambium.

• The vascular cambium is located between the primary xylem and primary phloem and forms a cambium ring.

• The cambium ring consists of secondary xylem on the inner surface and secondary phloem on the outer surface.

• Secondary xylem is formed more actively, resulting in the crushing of primary and secondary phloem.

• The cambium also forms secondary medullary rays, which extend radially through the secondary xylem and phloem.

• Secondary xylem tissues formed during cambium activity are commercially known as wood.

Annual Rings in Tree Trunks

• The cambium activity is influenced by physiological and environmental factors, resulting in the formation of annual rings.

• In temperate regions, the cambium is more active during spring, forming wider vessels (springwood).

• During winter, the cambium is less active, forming narrower vessels (autumn wood).

• Springwood is lighter in color and has a lower density, while autumn wood is darker with a higher density.

• The annual rings represent the central layers of the stem in an old tree.

Heartwood and Sapwood

• Secondary xylem turns dark brown due to the deposition of organic compounds, making it hard and durable.

• Heartwood is the dark, highly lignified region of the wood that provides mechanical support but does not conduct water.

• Sapwood is the lighter peripheral region of the secondary xylem involved in water and mineral conduction.

Chapter 1: Secondary Growth in the Cortex

• The cortex is a region where secondary growth occurs due to vascular cambium activity.

• The stem increases in girth, causing the cortical and epidermal layers to rupture.

• New protective cell layers need to replace the ruptured layers.

Supporting details:

• Secondary growth in the cortex is facilitated by the vascular cambium.

• The increase in stem girth leads to the rupturing of the cortical and epidermal layers.

• The ruptured layers need to be replaced with new protective cell layers.

Chapter 2: Cork Cambium and Paradigm Tissues

• Cork cambium or Felagin is another meristematic tissue that develops in the cortex region.

• Cells on both sides of the Felagin differentiate into different tissues.

• The inner surface cells differentiate into the secondary cortex or Feladumb.

• The outer surface cells differentiate into cork or vellum tissue.

• The resulting tissues from secondary growth in the cortex are collectively called paradigm tissues.

Supporting details:

• Cork cambium or Felagin develops in the cortex region.

• Cells on both sides of the Felagin differentiate into different tissues.

• The inner surface cells differentiate into the secondary cortex or Feladumb.

• The outer surface cells differentiate into cork or vellum tissue.

• The tissues formed from secondary growth in the cortex are collectively called paradigm tissues.

Chapter 3: Buck Bark and Lenticels

• Outside the vascular cambium, the secondary phloem and paradigm tissues are known as buck bark.

• Buck bark forms the outermost layer of the stem and roots of woody plants.

• Early or soft buck bark is formed in the early season, while late or hard buck bark is formed at the end of the season.

• Gaseous exchange between internal living cells and the outer atmosphere is cut off due to the formation of bark.

• Lenticels, lens-shaped openings on the stem, facilitate gaseous exchange.

Supporting details:

• The secondary phloem and paradigm tissues outside the vascular cambium are known as buck bark.

• Buck bark forms the outermost layer of the stem and roots of woody plants.

• Early or soft buck bark is formed in the early season, while late or hard buck bark is formed at the end of the season.

• The formation of bark cuts off gaseous exchange between internal living cells and the outer atmosphere.

• Lenticels, lens-shaped openings on the stem, facilitate gaseous exchange.

Chapter 4: Secondary Growth in Dicot Roots

• Secondary growth in dicot roots is similar to that of dicot stems.

• The vascular cambium develops from the pericycle tissue located below the phloem bundles.

• The cambium ring initially appears continuous and wavy but later becomes circular.

Supporting details:

• Secondary growth in dicot roots is similar to that of dicot stems.

• The vascular cambium develops from the pericycle tissue located below the phloem bundles.

• The cambium ring initially appears continuous and wavy but later becomes circular.

Chapter 5: Secondary Growth in Dicots and Gymnosperms

• Secondary growth in stems and roots mainly occurs in dicots and gymnosperms.

• Monocots lack secondary growth.

Supporting details:

• Secondary growth in stems and roots mainly occurs in dicots and gymnosperms.

• Monocots lack secondary growth