Characteristics of Plantae
Plants are eukaryotic multicellular organisms, and have cell walls which are made of cellulose. They are autotrophs, so they obtain energy though photosynthesis which is the process by which green plants and some other organisms use sunlight to synthesize foods from carbon dioxide and water: The chemical reaction is 6CO2 + 12H2O + light → C6H12O6 + 6O2 + 6H2O. Plants reproduce both sexually and asexually. They live in land and water environment. Plants have organs and organ systems. The leaves collect and absorb sunlight to convert to glucose. The leaves have a waxy coat on them to shield against water. The root system, which branches out, provides support and absorbs water. The stem provides support and the petal / flower / bud is the reproductive organ of the plant.
Tissue Systems
Dermal tissue systems: Dermal tissue systems have epidermis and periderm. The epidermis is a single layer of concentrated cells on the outside of the plant acting as a “skin”. Its job is to cover and protect the plant. The epidermis regulates gas and water exchange though guard cells in the stomata which act like pores. The stomata can also secrete chemicals onto the outside of the cell when needed. The periderm (bark) replaces the epidermis in plants that go through secondary growth. Periderm is different from epidermis because periderm is multilayered as opposed to epidermis which is single layered. Periderm has cork cells which are nonliving cells which protect and insulate the plant. The Periderm is important because it protects it from pathogens and injury.
Ground tissue systems: Ground tissue is surrounded by the dermal tissue. Ground tissue will provide support for the plant and it also stores materials in the roots and stems. Ground tissue in leaves are packed with chloroplasts, which is where the photosynthesis process makes nutrients for the plant. Three types of cells can be found in the ground tissue: parenchyma, collenchyma, and sclerenchyma. Parenchyma cells stores nutrients and water. Photosynthesis occurs in these cells in the leaves. Collenchyma cells give the plant support, but still allow the plant to grow and move. The sclerenchyma cells also give support to the plant, but they have a hardening agent so they are much more rigid.
Vascular tissue systems:The xylem and phoelem make up the vascular tissue system. The xylem is made up of tracheids and vessel elements. They both create a hollow tube like inside which helps transport water and nutrients to the plant. The Phoelem have cells that help move sugar and other molecules made from photosynthesis from the leaves to the rest of the plant.
Ground tissue systems: Ground tissue is surrounded by the dermal tissue. Ground tissue will provide support for the plant and it also stores materials in the roots and stems. Ground tissue in leaves are packed with chloroplasts, which is where the photosynthesis process makes nutrients for the plant. Three types of cells can be found in the ground tissue: parenchyma, collenchyma, and sclerenchyma. Parenchyma cells stores nutrients and water. Photosynthesis occurs in these cells in the leaves. Collenchyma cells give the plant support, but still allow the plant to grow and move. The sclerenchyma cells also give support to the plant, but they have a hardening agent so they are much more rigid.
Vascular tissue systems:The xylem and phoelem make up the vascular tissue system. The xylem is made up of tracheids and vessel elements. They both create a hollow tube like inside which helps transport water and nutrients to the plant. The Phoelem have cells that help move sugar and other molecules made from photosynthesis from the leaves to the rest of the plant.
Roots and their Functions
Tap Roots
A tap root is a type of root that grows downward. It penetrates the earth without dividing searching for food and water. Many tap roots are cultivated as foods because they hold so much water and nutrience e.g. carrot, parsnip.
Lateral Roots
Lateral roots grow from the primary root which acts as a anchor for the plant. The lateral roots stretch and extend horizontally. This design helps the plant absorb water and food from the soil
Advetitious Roots
Adventitious roots are roots that don't grow from root tissue. They grow from stem or leaf tissue that happened to touch soil of moist material. Adventitious roots will grow as a result from stress or injury of the plant.
Fibrous Roots
A fibrous root system is a root system where all the roots are the same width and length, but branch out to create a mat of roots. These root systems are the most efficient at absorbing nutrients.
Stems and their functions
Herbaceous stems
Herbaceous stems are soft and fragile. Plants who have these stems usually die at the end of a season. A herbaceous plants may be annual, biennial or perennial. They do not have a rough or woody outside like we see in trees or bushes. Many flowering ground plants have herbaceous stems. Tulips, dandelions, weeds etc. are all are example of plants that have herbaceous stems.
Ligneous Stems
Ligneous stems are much more sturdier than herbaceous stems. We typically see Ligneous stems on tree's and shrubs, and things with woody stems and trunks. Ligneous stems have a woody bark outside skin and a thick dense inside. Ligneous plants, with true woody stems, contain wood which is primarily composed of structures of cellulose and lignin which provide support and a vascular system used to move water and nutrients from the roots to the leaves and sugars from the leaves to the rest of the plant.
Leaf Types
Frond
A frond is a large divided leaf. Frond leaves are fern leaves. Fronds have a stalk called the petiole which support the leaf, a flattened spread out structure.The blades may be simple with no divides, have divides or have deep divides to resemble a feather.
Conifer
Conifer Leaves are long, thin and have a needle-like appearance, but others, including most of the Cupressacae and some of the Podocarpacae, have flat, triangular scale-like leaves. Podocarpacae have broad, flat strap shaped leaves. Others have more a needle shape.
Angiosperms
Most flowering and fruiting plants have these leaves.
Lycopodiophyta
Oldest type of leaf. These leaves have spores in which they reproduce by. Many mosses have these type of leaf.
Sheath Leaves
also known as monocots, are one of two major groups of flowing plants (or angiosperms) that are traditionally recognized, the other being dicots. This leaf structure is the strongest and can help protect the plant with shape blades.
Leaf Function
Leaves are where photosynthesis takes place. The cells, in the leaf, contain chloroplasts; these contain chlorophyll which converts carbon dioxide, sunlight and water into glucose sugar. This food is used and stored by the plant to grow and reproduce. 6CO2 + 12H2O + light → C6H12O6 + 6O2 + 6H2O.
Also leaves provide an area for transpiration and gaseous exchange.
Some shapes of leaves help the plant collect water. Depending on the shape of the leaf, it can spread rainfall water to where ever the roots are.
Also leaves provide an area for transpiration and gaseous exchange.
Some shapes of leaves help the plant collect water. Depending on the shape of the leaf, it can spread rainfall water to where ever the roots are.
Leaf Anatomy
Guard cells: protect the stoma and regulate air control. They prevent the leaf from drying out.
Stoma: The stoma regulate gas exchange. Carbon Dioxide goes in and Oxygen goes out
Waxy Cuticle: The waxy coating stops the leaf from desiccating.
The Upper Epidermis: protects the leaf
Palisade Mesophyll: consists of one or several layers of elongated, narrow parenchyma cells. Chloroplasts are especially concentrated in the palisade mesophyll and it is in these cells that much of the photosynthesis in a tree takes place.
Stoma: The stoma regulate gas exchange. Carbon Dioxide goes in and Oxygen goes out
Waxy Cuticle: The waxy coating stops the leaf from desiccating.
The Upper Epidermis: protects the leaf
Palisade Mesophyll: consists of one or several layers of elongated, narrow parenchyma cells. Chloroplasts are especially concentrated in the palisade mesophyll and it is in these cells that much of the photosynthesis in a tree takes place.
Asexual Reproduction
Asexual reproduction is the reproduction of organism without need of another organism.
How might a plant reproduce asexually?
Runners/ stolons - Stolons are horizontal connections between organisms. They may be part of the organism, or of its skeleton; plants such as strawberries and grass types.
Fragmentation - body part of the parent breaks off and can grow into a copy of the parent plant.
Budding - when plants grow a mini plant off of the parent plant that eventually grows into a full size adult
Rhizome - is an underground stem that grows horizontally near the soil surface.
Tuber - The tops or sides of the tuber produce shoots that grow into typical stems and leaves and the under sides produce the roots. The below-ground stem tuber is normally a short-lived storage and regenerative organ developing from a shoot that branches off a mature plant.
How might a plant reproduce asexually?
Runners/ stolons - Stolons are horizontal connections between organisms. They may be part of the organism, or of its skeleton; plants such as strawberries and grass types.
Fragmentation - body part of the parent breaks off and can grow into a copy of the parent plant.
Budding - when plants grow a mini plant off of the parent plant that eventually grows into a full size adult
Rhizome - is an underground stem that grows horizontally near the soil surface.
Tuber - The tops or sides of the tuber produce shoots that grow into typical stems and leaves and the under sides produce the roots. The below-ground stem tuber is normally a short-lived storage and regenerative organ developing from a shoot that branches off a mature plant.
Plant Hormones
Auxin - Auxin inhibits root growth and development
Cytokinin - promotes cell division, or cytokinesis, in plant roots and shoots.
Gibberelin - regulates stem elongation, germination, dormancy, flowering, sex expression, enzyme induction, and leaf and fruit senescence.
Ehtylene - stimulates leaf and fruit abscission, stimulates flower opening, and stimulates fruit ripening
Abscisic Acid - Stimulates the closure of stomata, Inhibits limited shoot growth, Induces seeds to synthesize storage proteins
Cytokinin - promotes cell division, or cytokinesis, in plant roots and shoots.
Gibberelin - regulates stem elongation, germination, dormancy, flowering, sex expression, enzyme induction, and leaf and fruit senescence.
Ehtylene - stimulates leaf and fruit abscission, stimulates flower opening, and stimulates fruit ripening
Abscisic Acid - Stimulates the closure of stomata, Inhibits limited shoot growth, Induces seeds to synthesize storage proteins
Plant Tropism
Plant Tropism is the biological phenomenon of plants moving toward something due to environmental changes.
Types of Tropism...
Phototropism - Growth or movement toward light
Chemotropism - Growth or movement toward certain chemicals
Gravitropism - Growth or movement toward the ground
Thigmatropism - Growth or movement toward touch
Phototropism video below
Types of Tropism...
Phototropism - Growth or movement toward light
Chemotropism - Growth or movement toward certain chemicals
Gravitropism - Growth or movement toward the ground
Thigmatropism - Growth or movement toward touch
Phototropism video below