Plant Form and Function

Plants are multi-cellular organisms, which is an organisms that consist of more than one cell.There also known as eukaryotic organisms.They have a cell wall made of cellulose.They are photosynthetic, meaning that they convert light energy to chemical energy by means of chloroplasts located primarily in their leaves. And last but not least is that they use water via capillary action.


Plants have three types of classification. These types of classification are nonvascular, seedless vascular and seeded vascular. Nonvascular plants(Bryophtyes) are plant have no vascular tissue's in other words no  stems, roots, and leaves. Mosses, Liverworts, and Hornworts belong to that category.Seedless vascular(tracheophytes) are plants that contain vascular tissue, but do not flower or seed.Ferns, horsetails, Whisk ferns, and Club mosses goes into that category.Seeded vascular(tracheophytes) are plants that have the vascular tissues xylem and phloem.

Vascular Tissues
In the Tracheophytes group there are two types of tissues that help seeded and seedless plants carry food into it. There are called Xylem and Phloem. Xylem is a tissue that conducts water and minerals up a plant from its roots.Phloem is another tissue that uses it's vessels to carry nutrient, such as glucose, to the plant. Xylem has two types of cells called tracheids and vessels elements.Tracheids cells are long and thin while vessel element are short and thick.

When water enter the plants by going through the roots. Roots have special characteristics called root hairs which increases the surface area for absorption of materials. Then it goes down to the phloem tissue. Phloem cells are made of sieve tube elements and companion cells. Sieve tube element are the cells that actually carry the nutrients in the plants and companion cells just hang around to  lend "support" to sieve tube elements of tracheophytes. Ferns are one of the greatest example of transportation of water, minerals, and nutrient through out itself because of it's vascular tissue. Ferns are the most ancient and simplest plants of tracheophytes. But they need huge amount of water to fertilize because of it being seedless.

Gymnosperms and Angiosperms: Tyracheophytes subdivided even further
In the seeded plant there two types of plant known as Gymnosperms and Angiosperms.Gymnosperms are the woody plants and are the oldest long lasting plants. Spruces,hemlocks, and fir are perennial which means they live year after year. Knowing the age of an gymnosperms is by counting the number of  tree rings. Tree rings are composed of dead xylem showing the annual tree growth.
Angiosperms are known as"flowering plants". They are most varied and widespread. The have seeds are usually inside a fruit or a nut. Some Angiosperms are woody, for example oak, cherry and walnut. Flowering plants can be divided into two types of classes called monocots and dicots. Monocots have one single cotyledon-the embryonic seed leaf. There known to have leaves with parallel veins and flower parts in multiples of three.Orchids and lillies are good examples of monocots.Dicots have two cotyledon. They have broad leaves with netted veins, and flower parts in multiples of four or five.

Life Cycle of Plants

In the cell cycle plants have an alternation of generations which is a pattern of reproduction occurring in the life cycles of many lower plants and some invertebrates, involving a regular alternation between two distinct forms. In other words, plants have spend part of their lives as haploids and part of their lives as diploids.The word haploid means a single set of unpaired  chromosomes and the word diploid containing two complete sets of chromosomes, one from each parent. In the plant cell cycle a haploid plant is called a gametophyte because it produces haploid gametes(eggs & sperm). The gametes then come together to create a diploid plant called as sporophtye. The sporophyte then makes haploid spores due to meiosis. When hapliod gametes unite during fertilization, a zygote(diploid cell) if made. This sporophyte begins the sporophtye generation which makes the zygote divides by mitosis and develops into a multi-cellular embryo that is supported and protected by the gametophyte.Then the sporosphyte plant divides and produces spores meiosis. The spores are known to be the first stage of gametophyte generation. It's capable of growing into a multi-celluar  gametophyte plant.


Plants grow by having unspecialized, actively dividing cells called meristems. This dividing cells make the plant grow by two ways. There are primary growth and secondary growth. Primary growth increases the length of a plant. This is caused by a tissue called apical meristems and are located in the tips of roots and stems. Secondary growth is carried out by the lateral meristems which makes the dividing cells increase the girth, or width of a plant. The lateral meristem is located on the sides of stems and roots. These lateral meristem produces two types of cells called vascular cambium and cork cambium. Vascular cambium produces secondary xylem and secondary phleom, replaces the previous(primary) xylem and primary. The cork cambium produces the tissues of the outer bark of a tree. Plants also have this thing called lenticels, which allows for gas exchange through the bark.


Roots have 3 main regions: the root tip, the elongation region and the maturation region. The root tip and elongation regions ate the sites of ongoing primary growth. The root apical meristem has small cells that continuously divide, forming of cell division. As this continues, new left cells grow rapidly in length which push the root tip along. Elongation occurs when cells take in water. Tiny root hairs, extensions of the epidermal cell form and create an increased surface area through water dissolved minerals can move into the plant. Finally the maturation zone, which lets vascular tissue ,makes primary xylem and phloem which forms the stele- an inner concentric cylinder. There's another cylinder cell that surrounds the primary xylem and phleom called pericycle.
Leaves adapt on types of environment there in. They can modify themselves to have spines for protection, they can adapt for water storage if they live in harsh environments as in the dessert.And lastly some can adapt for trapping pray. There this plants that digest insects. The reason is because they grow in soils deficient of essential nutrients, mostly nitrogen, which forces them to eat insects. For example, a Venus flytrap has tiny hairs that act like mouse trap the moment it feels something touching it. And as Pitcher plant it made it's leave very slippery and deep for insects to fall in. Ounce it falls into a mixture of water and enzymes. As you know what enzymes do break down stuff.

Flowering Plants

There are several organs of a flower. They are stamen, pistil, sepals, and petals. Flowers have male and female parts of it's structure. The male parts are collectively called stamen and the female parts are called pistil.Sepals are the green, leaf-like structures that cover and defend the flower while the brightly colored petals attract potential pollinators.

The Stamen(male)
The stamen is an anther and a filament. The anther produces pollen grains also known as microspores(sperm cells). Microspores are then released into the air. The filament is the thin stalk that holds up the anther.

The Pistil(female)
The pistil has three structures called the stigma,style,and ovary. The stigma is the "sticky"portion of the pistil that catches pollen grains. The style is a tube like structure attaches the stigma and the ovary.The ovary is where fertilization happens. Inside the ovary is the ovules which has the plant's equal female gametophytes called megaspores.

Double Fertilization
Plants reproduce by carrying out a process called double fertilization. It's when microspores land on the stigma, it starts to germinate and grow out a thin pollen tube down the style, that connects with the ovary. The microspores divide into 2 sperm nuclei. one sperm goes with an egg nucleus to make a zygote. Then the zygote will make a plant. While the other sperm nucleus with two polar nuclei in the ovary making an endosperm. The endosperm would be food for the plant made from the other sperm.

Early Seedling Development

As soon as the seed starts to germinate, different parts of the plant begins to develop. Cotyledon are first to appear out.For a short time they keep all nutrients for the plants. Then comes the epicotyl which the tip of the plant. This becomes stem and leaves. And finally last but not least the hypocotyl, stem below cotyledon. This becomes the roots of the plants.A well-defined embryonic root is referred as a radicle.
Plants in sexual reproduction gets triggered by photoperiodism which is plants or flowers response in the change of daylight and darkness. This makes plants fall into three groups: short-day plants, plants long-day plants and day-neutral plants. Short-day plants  when plants require a long period of darkness. They usually bloom in the summer or fall season when the daylight is decreasing. Long-day plants mean that when plants need short periods of darkness. They bloom in the spring and summer when daylight is increasing.And finally day-neutral plants don't flower in response to daylight changes at all, instead the temperature.

Vegetative Propagation
Sometimes flower plants don't always reproduce through fertilization. They can reproduce asexually. This is known as vegetation propagation. This means to take part  of a parent plant (roots,stems, or leaves) to make another plant. Example of this vegetative propagation are Onions,Strawberries,Potatoes,Seedless oranges.

Tropical Tropisms
Have you notice why your plant have always looked to where the sun is? Well this known as phototropism.Plant usually grow up and down, meaning the branches of a tree grows up while the roots grow downward to dirt(soil) looking for water. All of this action are tropisms of the plants behavior. Tropisms is a turning response to a stimulus.Plants have 3 common tropisms:Phototropism,Gravitopism, and Thigmotropism.Gravitopism is to how plants respond to gravity.How they grow away from gravity.And last but not least Thigmotropism is how plants respond to touch. How neatly the plant grows on something else.All of these response are initiated by hormones. The major plant hormone is auxins.Auxins provide many functions in. There the brains of the plants. Other major hormones that help out the plant like:
gibberellins-promote stem elongation, especially in dwarf plants,cytokinins-promote cell division and differentiation,ethylene-Induces leaf abscission and promotes fruit ripening, & abscisic acid-Inhibits leaf adscission and promotes
bud and seed dormancy.