Laboratory Activities 7 & 8: Plants Used

• Photos and images of plants used in lab activities including scientific/common names
• Plants include: Mangifera indica (Mango), Psidium guajava (Guava), Solanum melongena (Eggplant), Pyrus communis (Pear), Apium graveolens (Celery), Helianthus annuus (Sunflower), Zea mays (Corn), Paspalum conjugatum (Carabao Grass), Vigna radiata (Mongo)
• More plants included: Commelina benghalensis (Alicbangon), Ranunculus (Buttercup), Cynodon dactylon (Bermuda Grass), Hibiscus rosa sinensis (Gumamela), Ixora coccinea (Santan), Aglaonema (Donna Carmen), Chlorophytum comosum (Spider Plant)

Similar Features

• Three organelles usually appear in plant specimen photomicrographs: cell wall, nucleus, cytoplasm
• Plant tissues consist of similar cells grouped to perform a specific function
• Visual cues for similar cells in plant tissues: Size, shape, wall thickness
• Cells with primary walls form thin walls, cells with secondary walls form thick walls
• Cell walls with methyl green stain appear green or blue-green due to cellulose
• Cells with safranin stain interact with lignin, which makes up secondary walls, and appear red
• Remember SSWC as initials
• Plants classified by cotyledon number (seed leaves) in embryonic seedling within seed
• Monocotyledon: one cotyledon
• Dicotyledon: two cotyledons

Difference between Monocots and Dicots

• Monocots feature one cotyledon, parallel veins, complexly arranged vascular bundles, fibrous root systems, and floral parts usually in multiples of three
• Dicots feature two cotyledons, netlike veins, vascular bundles arranged in a ring, a taproot, and floral parts typically in multiples of four or five

Plant Tissues

• Permanent tissues are already differentiated and no longer actively divide
• Simple tissues consist of one cell type e.g. ground and dermal tissues
• Complex tissues consist of more than one cell type working together e.g. vascular tissues
• Meristems are regions of active cell division and plant growth, usually at plant nodes

Types of Meristematic Tissues

Lateral Meristem

• Responsible for the girth of a plant
• Only in woody plants, producing cork cells of tree barks and increasing diameter
• Grows parallel to the axis of the plant
• Consists of the cork cambium (epidermal) and vascular cambium (xylem and phloem)

Apical Meristem

• All plants primarily grow here, increasing in height
• Located at the apex, or tips of plants
• Two apices: shoot apical meristem (SAM) and root apical meristem (RAM)

Intercalary Meristem

• Found in grasses at the nodes
• Increases height, counterpart of axillary meristem
• Only in grasses, as monocots don't have lateral and axillary growth
• Helps regeneration of plant parts removed by grazing herbivores

Axillary Meristem

• Meristematic cells develop into vegetative (branch) or reproductive (flower) parts, depending on season
• Meristem creates new undifferentiated cells to form different parts
• Dicots have SAM/RAM, lateral, and axillary meristems
• Monocots have SAM/RAM, and intercalary meristem because they increase in height
• However, they do not have lateral meristems, as they do not increase in girth due to the absence of vascular cambium, bark, and axillary meristems

Plant Tissue Systems

Dermal Tissue System

• Protects the plant from its external environment
• Squat or less cubic-shaped cells

Vascular Tissue System

• Transports water, sugars, and nutrients throughout organism

Ground Tissue System

• Site of photosynthesis and storage for water and sugars, makes up the majority of plant interior

Coleus blumei Shoot Apical Meristem

• Various labeled parts: Procambium, Ground Meristem, Leaf Gap, Trichomes, Apical Meristem, Developing Leaf Primordia, Leaf Primordium, Axillary Bud, Procambium

Parts of Meristematic Tissues

Protoderm

• Precursor to dermal tissues, first layer of small, rectangular or cuboidal cells arranged in a line
• When zoomed, has a large nucleus (presence means it's active and still has the ability to divide)
• Thin, composed of cellulose and pectin
• Gives rise to the epidermis

Dermal Tissue

• Includes the epidermis and periderm, which make up the outer protective layer and serves two functions: protects the inner tissues from injury or infection, preventing dehydration
• Cuticle: waxy layer of cutin on the cell wall of plants prevents water loss during transpiration, forms water-resistant cutin (except in root growing regions)
• Epidermis: outer layer that covers primary plant body except shoot and root apical tissues

Epidermis

• In non-woody plants, it is usually a single tissue layer
• Acts as a barrier to the external environment
• Aids in regulation of gas exchange via stomata
• Periderm forms during secondary growth that replaces the epidermis in older regions of woody stems and roots
• Stomatal Apparatus Monocot stomata arranged in parallel rows along leaf length due to parallel venation
• Dumbbell-shaped guard cells swollen with a narrow central region
• Amphistomatic characteristic makes stomata present in both upper and lower surfaces

Trichomes

• More abundant on the abaxial side in grasses
• Dicot: stomata is scattered on the leaf surface
• Bean or kidney-shaped
• Hypostomatic: More abundant on the abaxial side
• Consists of the stoma, guard cells, nucleus, chloroplast, cell wall and epidermal cell

Stoma

• Facilitates gas exchange
• Helps in transpiration and removal of excess water. Closes at night to prevent water loss. Maintains moisture balance
• Guard cells (G): specialized dermal cells that facilitate gas exchange in shoots
• Commonly known as plant hairs
• Epidermal appendages that protects the plants from herbivores (physical barrier or secretion of defensive compounds)
• Reduce water loss by trapping moisture
• Present in herbacious which are watery
• Reflect UV radiation
• Regulate temperature through insulation
• Assist in seed disperal by forming hooks or barbs

Types of Trichomes

• Multicellular - Clear segments or divisions along the trichome body
  • Unicellular - Single elongated structure, hair-like projection
  • Uniseriate - Cells are arranged in a single vertical row
  • Multiseriate - Trichomes grow in multiple rows Glandular - Have bulbous or swollen tip, sticky and shiny due to secreted substances (oils, resins, and other compounds)
  • Non-glandular More rigid and hair like, no visible secretory structure at the tip
• Serve as physical barriers protecting the plant from herbivores, excessive sunlight, or water loss.
  • Simple/Unbranched - Single, straight or curved form with no side branches
  • Dendritic/Branched - Multiple side branches extend from the main axis, tree-like or complex appearance

2. Procambium

• Capitate: Rounded head on a stalk
• Peltate: Shield-shaped with a central stalk attachment'
• Procambium development
  • Peltate: trichomes are those with a disk-shaped apical portion atop a peltately attached stalk
  • Procambium is the precursor to vascular tissues
  • Narrow, elongated, tightly packed, has prominent nucleus, and has dense cytoplasm
  • Xylem and phloem when differentiated

Vascular tissues

• Xylem: transports water and nutrients -Described as heterogenous, composite and complex -Unidirectional (upward) movement -Contains vessel cells, tracheids, fibers and parenchyma -Seen at the middle of cross-sections of plants -Features tracheids, which have long cells with oblique end walls and round pits in the walls
• Two main pathways for water transport
• -- Apoplastic water flow: through the cell wall
• -- Symplastic water flow: through the cytoplasm

Pholem

• Ray parenchyma are small round cells lined together
• Phloem: transports sugars and metabolic products
• Multidirectional movement (up/down). Contains sieve cells and companion cells Surrounds the xylem associated with semicircular structures called bundle caps’ . Houses sieve tubes and companion cells'.
• Sieve tubes’ major conducting cells for sugar in the phloemForms slime plugs when stressed
• Companion cells: for metabolic functions

Endodermis - tight cells in roots of plants

• Has'casparian band, or ring-like structures at the center. Casparian band: prevent waters water and "nutrients" from entering the stele through apoplasto pathway
• Composed of phelloderm/secondary cortex, cork /phellem, cork cambium .Secondaray tissue;

Ground Meristem

• Also known as Phellogen, also known as Lateral that produce cortex (phellem) to outside secondary cortex
• Known as the phellogen to cortex called phelloderm)
• Vascular Tissue

Origination of vascular origin - Fasiccicular cambium - Wthin Vascular bundle.

• Type meristem - primary and secondary primary and secondary vascular tissues
• Secondary xylem that will be conduction. Secondary vascular (additional)

Ground Meristem

• The is precurser to crotex pith cells
• The cells also also depend of tiisue forming
• Has ground tissues arises whne differnertiated
• Isocompasoed tissues.Parenchya,colenchya
• Colenchymia. uneven thicker walls

Metaxylem and Protoxylem

• Additional structures of secondary
• replaces pholem-
• thick walls
• ligfied cells
• types- sclerieds called reduced forme

Fibers- Long narrow and thick

• cell walls
• Lignified cells
• Ldead adutily (stsins,better
• Types.skereids A stone

cellls

• fibers-Long narrow long thin
• root appical most meristm
• zones has rootcap
• penrate the soil will detct the gravity
• growth absorption

External structure of stem

• terminal or (a-Pical)
• barks- opening on scale (faciltative)
• creshent shape by leafe
• small dot due to the leave

Stem

• the by the terminal
• girth secondary leaf sheath
• phytonal constucl unit
• culm. stem of grass

Photosynthesis

• has. Phyallotxy and paterns its stem a-daxial top
• abexial Bpttp,

Leaf Types

• Leaf Type include Image/Notes, Coleus blumei, Shoot apex, Leage primodia, lateral bulb with everything in allium cepa

Root system

• Roo claisffciation based on its origin
• Root ckaification based manner. Has large central growing duownward. Fpund inm angoipsrm, Thim bracnrhming of its coide yo its surc