Lecture 4 Flashcards
Plant Growth
- all flowering plants are either broadleaf plants (dicots) like the geranium or plants with grasslike leaves (monocots) like this Iris
-Modular
-Size and Shape plasticity
-Stem= above ground axis
-Leaf - solar collectors
-Shoot= stem + leaves
-Root
-Node=Point of leaf or flower development
Internode
Plasticity of Shape (leafless Plants?)
Cactuses (Opuntia) have small fleshy leaves 100-1000um long and spines
Plasiticty of shape (Stemless Plants?)
-Ghost orchid ( Polyradicion lindenii) are composed mainly of roots that photosynthesis
Plasticity of shape (Rootless Plants?)
Tumble weed (Tillandsia stramina) are composed mainly of shoots - has small root system
Cell theory for plants
- Plants comprised of cells
- Cells organized into tissue
- Organs made up of 1 or more tissues
- complex plant structures made up of more than 1 organ
- Tissues organized into tissue system (ground tissue system, Vascular system, Dermal system)
Organs
- made up of 1 or more tissues
- Part of the cell theory applied to plants
- examples of organs are: steam, root, and leaf
Complex plant structures
- made up of more then 1 organ
- Part of the cell theory applied to plants
- examples of these are: bud, flower, branch, fruit, seeds
Tissues organized into tissue systems
- Ground tissue system
- Vascular system
- Dermal system
Ground tissue system
- Roots
- carries out photosynthesis, stores photosynthetic products, and helps support the plant
Vascular system
- Stem
- comprised of xylem and phloem
- conducts water and solutes throughout the plant
- water and nutrient movement throughout plant
Dermal system
- Leaf
- the outer covering of the plant
Plasmodesmata
- Cytoplasmic connections between plants cells
- Symplastic continuity
Parenchyma Cells
-Thin primary wall with ability to stretch and expand
Functions of Parenchyma cells
- photosynthesis, storage, secretion
- ability to differentiate into other cell types
Collenchyma Cells
- Flexible yet supportive tissue
- Elongated cells with primary wall that are unevenly thickened
- example: Strings of celery, these celery strings are made up of collenchyma cells
Sclerenchyma Cells
- Possess both primary and secondary walls
- Thick secondary cell walls are strong and hard
- Provide support
- Are often dead
- 2 major types - sclereids and fibers
Sclerenchyma Cell
Two Major types
- Sclereids - short and variable in shape
- Fibers - long, tapered cells often occurring in groups
Sclereids
- A major type of Sclerenchyma Cells
- Short and variable in shape
- Example: Cherry stone
Fibers
-A major type of Sclerenchyma cells
long, tapered cells often occurring in groups
-Example: wood
Vascular System
- Xylem - conducts water and dissolved minerals
- Phloem - conducts food materials
- Angiosperm vascular systems contain tracheids, vessel elements, paranchyma cells, fiber
Angiosperm vascular systems
- Contain tracheids
- vessel elements
- parenchyma cells
- fiber
- also contain sieve tube elements, companion cells, parenchyma cells, and fiber cells
Phloem
- conducts food materials
- conducts mainly organic compounds
- composed mainly of Sieve-tube elements
Sieve-tube elements
- are alive at maturity but have no nucleus
- elongated, tube-like
- no nucleus
Companion cells
serve as nucleus for the adjacent sieve-tube elements
Flax
Linum usitatissimum
- Bast fiber
- true fibers used from the stem often including phloem, cortex, and periderm
- oldest textile fiber used by humans
- fabric has been dated 10,000 yrs. old
- Egyptian tombs document cultivation
- Native to Europe and Eastern Asia, no wild populations persist today
- annual plants used for fiber and linseed oil
- Linen makes up 2% of world’s textiles
- flax fibers are 2-3 times stronger than cotton
- Used to make linen, hoses and mailbags
- lots of hand labor involved, thus Expensive textile
Dermal Tissue System
- Epidermis in herbaceous plants
- Periderm in woody plants
- Including some specialized as Guard cells, Trichomes (root hairs)
- Epidermal cells often secrete a waxy cuticle layer
Cotton (Gossypium spp.)
- A surface fiber
- Comes from trichomes (long epidermal hairs) attached to the seed coats
- independently domesticated in New and Old Worlds
Modular Additions
- Meristems = collection of undifferentiated cells; where cell division occurs, they are simple cells not specialized
- Apical meristem - where cell division occurs at the shoot of the plant (the top of the plant)
- Axillary meristem - cell division occurs here as well (aka axillary buds)
Primary Meristems
NEED TO ADD SOMETHING NOT SURE WHAT
Secondary Meristems
- examples: vascular cambium and cork cambium
Three Primary tissues
- Protoderm = undifferentiated tissue of stems or roots that becomes the epidermis
- Procambium = meristematic tissue that develops into xylem and phloem
- Ground meristem= meristematic tissue that became cortex, pith and ground tissue.
Cell Growth
- Growth of plant cells through water uptake
- Central role of vacuole = occupies large portion of cell volume
- Cell walls loosen, direction of expansion controlled by orientation of cellulose microfibrils
- expansion with water -> either elongates or widens based on orientation of cell wall fibers
Cell Differentaition
- specialized cells differ in the genes that are expressed
- Differential occurs when specialized cells take on distinctive structure and function
- May occur through unequal or asymmetric cell division
- Exposure to different environments (physical or chemical differences) - aka physical or chemical cues
Radial Symmetry
- Plant embryos have apical basal polarity (distinct tops and bottoms)
- The plant body has radial symmetry also known as phyllotaxy
- Example: Sunflower seeds are arranged radially, tiny sunflowers arranged radially, leaf attachment down the stem of a Poinsettia
Leaves
- Shoot Apical Meristem (SAM)
- Root Apical Meristem (RAM)
- Leaf Primordium (LP) indicated at the flank of the SAM
What are all plants comprised of?
Stem, Leaf, and Root
Modular Plant Growth
- means that plants can grow and shed parts and it doesn’t matter because it grows back, nothing negative happens, no damage
What is plasticity?
sizes and shapes can vary between individuals of a species
Root of plant
below ground for most plants, but some are above
- all have nutrient absorption, water absorption, and anchorage (anchors the plant)
Stem
Above ground axes
Leaf
Solar collector
Shoot
Stem and leaf.
sieve plate
- purpose - allows for the transfer of materials up and down the sieve-tube because it moves through the holes, not entirely digested, still some material there
- phloem has these
cuticle
- waxy cuticle blocks much of the moisture loss through this surface
Shoot tip (shoot apical meristem)
- aka SAM
Root apical meristem
- aka FAM
primary growth in stems
- the lack of wood
- doesn’t have cork cambium
leaf primordia
cell growth, pushes cells up from below
Protoderm (1 of 3 primary tissues)
undifferentiated tissue of stems or roots that becomes the epidermis
Procambium (2 of 3 primary tissues)
meristematic tissue that develops into xylem and phloem
Ground meristem
meristematic tissue that becomes cortex, pith, and ground tissue
guard cells
- control gas exchange in and out of the plant
- these cells are examples of specialized cells
Xylem
conducts water and dissolved minerals
