What is a Plant? (Parts, Functions & Types of Plants)

Last Updated on March 15, 2022 by Admin

Every gardener has to learn a little bit of botany. And while you don’t need a degree or be an expert it in, understanding the basics helps you grow and care for plants.

Just as importantly, it lets you troubleshoot and fix common problems your plants experience.

Why Do Plants Have Latin Names?

One of the first things you’ll notice with plants is that they come by many names. Some sound more complicated than others.

So why is that?

All plants have at least 2 names. These are their:

Common Name. Except for a very few rare ones, almost all plants have a common name. These are the English names we’re used to calling them by. A few examples include Aloe Vera, Ash Trees, Boston Ivy and Hydrangeas.
Botanical Name. These are the Latin scientific names of plants. That’s why they’re so much harder to pronounce, spell and remember. Add to that, they’re made of two parts, the genus, and species of the plant. For example Aloe Vera’s botanical name is Aloe barbadensis. The Boston Ivy’s is Parthenocissus tricuspidata.

The reason why all plants have botanical names is because it’s the most efficient way of uniquely identifying a plant. Why?

Many plants have multiple common names. An example here is the Anthurium, which many people also refer to as the Flamingo Flower or Flamingo Lily. If you weren’t aware, you’d think they were three different plants.
It’s a good way to separately identify plants with many species. For example, there are 120 species of the dracaena plant. But, many people refer to it just as dracaena. As a result, it can be confusing because they all look different. And, some are trees while others are small houseplants. By using their botanical names, it’s easy to differentiate the Dracaena Reflexa from the Dracaena Marginata or the Dracaena Massangeana.
Some common plant names can be misleading. For example, the lucky bamboo may look like the actual bamboo. But, it’s not even a bamboo at all.

Since no one regulates the use of common names, it’s easy to double, triple or repeat the same names to mean different plants.

By using a pair of names, it’s easier to uniquely identify each plant, albeit more difficult to pronounce or remember.

So, while it’s easier to remember the common names of plants, be aware that there could be many variations of plants using that same common name. At times, some plants, trees or grasses aren’t even actual species of that plant, a tree or even a grass.

Plant Anatomy – Parts of a Plant

Besides being able to identify plants via their botanical and common names, it’s likewise important to understand the different parts of the plants.

Now, I’m not going into the different parts of a plant in detail as you did in plant biology, botany or other horticulture classes, which will probably bore you.

After all, you want to learn about gardening, not the ins and outs of specific plants. Yet, it’s still important to have some basic knowledge of the different parts.

This will allow you to understand how they work. And, when the time comes to propagate, grow and prune them.

Like people, plants are made up of tissues that are grouped together to perform different functions. But in their case, you have two basic types of parts (organs). These are:

Vegetative. These include the roots, stems, leaves, shoots and buds of the plant. All of which are not involved in a plant’s sexual reproduction. But, they can be used for asexual reproduction like budding, cuttings and grafting. (see the chart below)
Reproductive. These include flowers, fruits, seeds and buds. In essence, all the parts that are involved in producing new seeds are included here.

If you noticed, buds appear in both groups. That’s because buds can be both vegetative or reproductive (floral). In some cases, they’re a mix of both.

Vegetative Parts of a Plant

A plant’s vegetative parts are those that are not involved with their sexual reproductive process. But, it’s important to understand that they can still be used to create new plants.

This is done via propagation, as you’ll see in the section below. That said, this reproductive process is asexual since it doesn’t involve any male or female gametes (cells).

Leaves

Leaves are the green foliage of a plant. Almost all plants have green leaves because this part is filled with chemicals that are green, namely chlorophyll.

That said, leaves aren’t there to make a plant look pretty. In fact, it has several functions. All of which are key to helping your plants live and grow.

A plant’s leaves are flat to make it efficient at absorbing as much sunlight as possible.

Why?

It’s because leaves are where photosynthesis happens. Photosynthesis is the process where the plant uses the light (ideally from the sun, but can be from grow lights), carbon dioxide and water it has collected to produce carbohydrates which in turn it uses as energy. The latter part is what’s called respiration, which incidentally also occurs in the leaves.

Finally, there’s transpiration, which is where the leaves lose excess water in the form of vapor. Just like how your body sweats to cool down, plants transpire to help regulate its temperature. It also does so to help water move up from the plant’s roots.

Stems

A plant’s stem is the long, often tall section that holds up the leaves, flowers and other parts of the plant that are above the soil.

In addition to providing structural support, it also allows water, nutrients and carbohydrates to move across different parts a plant.

It’s worth noting that stems are called many other names. But, in essence, they are and function like stems.

Trunk. These are prevalent in trees. Trunks are the main stem of woody plants.
Branches. These are stems which are not as big or thick as trunks. They are over 1 year old and will have other smaller, lateral stems come out from them.
Twig. Twigs are stems that don’t have leaves. They’re 1 year old or younger.
Shoot. A stem with leaves that is 1 year old or younger.

As you can see, all these terms are used to define a stem. The only difference is how they look and how old they are.

Buds

Buds are a little bit more complicated. That’s because you’ll find both vegetative and reproductive buds in plants.

That said, buds are parts of the plant where new growth comes out. As such, they are undeveloped shoots.

Vegetative or leaf buds are those where new leaves and shoots arise from.
Floral buds are where flowers or fruits arise.

Just as importantly, buds come in many different variations. They can be labeled by their:

Location: terminal (at the ends of the stem), axillary (the angle between the leaf and stem), adventitious (anywhere else; not in terminal or axillary positions)
Function: vegetative, floral, mixed (a combination of the two; thus, producing both shoots and flowers)
Morphology (how they look): hairy, scaly, naked or covered
Status: dormant, accessory or pseudoterminal

Roots

Roots are the foundation of your plant. They’re often overlooked because you can’t see them.

But, they play a very important role, if not the most important role, when it comes to keeping your plant alive.

The primary function of roots is to absorb water and nutrients. In traditional gardening, this will be from the soil. In hydroponics, it will be from the nutrient solution. And, in potted houseplants, it will be from the potting mix.

Similarly, the roots also transport nutrients and water to the stem.

And, the root system is what anchors the plant to the soil As such, it is what keeps the plant upright and prevents it from easily being pulled out of the ground.

Interestingly, while you can’t see it unless you pull the entire ball out, the root system makes up 20-30% of the entire plant.

More importantly, a plant’s roots affect the:

size of the plant
how it’s best propagated
its ability to adapt to different soil types

And, how well the root system grows depends on:

How compacted the soil is. Loose soil allows it to extend outwards. Compacted soil prevents it from growing as much as it normally would.
Balance of oxygen and water. Porous soil that allows air to flow and retains water well giving the roots air and moisture it needs. Lack of oxygen prevents it from properly absorbing nutrients.
Soil fertility. The more fertile the soil, the faster the roots grow and the deeper they’re able to extend under the ground.
pH of the soil. Having soil that’s within the ideal pH range allows the plant to properly absorb all the nutrients in the soil.

Related

Sexual Reproductive Parts of a Plant

In this section, we’ll focus on the reproductive parts of flowering plants (angiosperms). Here’s it’s important to understand that unlike people different plants reproduce differently. So, while they may have the same parts, the actual process can vary significantly.

These parts include flowers, fruits and seeds.

Flowers

For most people, plants are all about their flowers. It’s what makes them bright, colorful and beautiful to look at.

But, from a functional perspective, flowers are meant for sexual reproduction in plants. In fact, it’s actually the reason why flowers look so lovely and smell so fragrant.

The goal of their looks and scent is to attract pollinators like birds and bees, which play a big role in pollination, the process where the pollen (male genetic material) is transferred from the male part of the plant to the female part of the plant which results in fertilization.

Yes, like humans, plants have male and female “parts”.

The male portion is the stamen which holds pollen. The female portion is the pistil which holds the eggs.

The wind, birds, bees and other insects are the most common ways wherein pollen grains are moved from the stamen to the ovary in the pistil for plant reproduction.

Fruits

Fruits are the result of pollination when the embryo starts to develop. While we’re familiar with them as a kind of food, they’re actually there to protect the seed.

That’s why fruits have either a fleshy exterior as apples and pears do. Or, they are hard on the outside like nuts.

That said, fruits are lovely to look at, tasty, colorful and in many cases fragrant. This makes them attractive to animals, including birds to carry them (and possibly eat them).

Thus, allowing the seeds to reach different places. And, if eaten, release the seeds in their feces.

Seeds

Seeds are mature ovules. Thus, they’re the result of plant sexual reproduction. They appear or grow in fruits. And, they contain new plants.

While some seeds like sunflower and pumpkin seeds can be eaten, most seeds are often replanted into the ground so that new plants can grow from them.

Basic Life Functions of Plants

Now that you know the basic parts of a plant, it’s time to understand the 3 basic functions it performs in order to survive and grow.

These are:

Photosynthesis
Respiration
Transpiration

It’s important to note that much like blood circulation, metabolism and digestion in humans, these functions go non-stop, except in some instances.

For example, when you don’t eat any food then digestion halts, at least temporarily. The same is true for photosynthesis. At night, when there is no sunlight, photosynthesis slows down.

That said, here’s how each essential function works and how they’re all related to one another.

Photosynthesis

In the process of photosynthesis, plants take in CO2 (carbon dioxide) from the air and combine it with water absorbed through their roots. They use energy from sunlight to turn these ingredients into carbohydrates (sugars) and oxygen, and they release extra oxygen to the air.

Photosynthesis is the process wherein plants turn CO2 (carbon dioxide), water and light into sugars (carbohydrates) they can use for energy (respiration) and oxygen.

As such, in a way, plants “make their own food”.

Here, the:

Plants get carbon dioxide from the air via the pores (stomata) on its leaves
It combines the CO2 with water its roots have absorbed from the soil
Finally, sunlight is used as energy to convert them into sugars and oxygen
Any excess oxygen is released into the air via the stomata

Once carbohydrates are produced, the plant can either:

Use it for energy
Store it
Use it to form complex compounds like proteins

These sugars are used by plants in many ways including for growth, growing fruit, forming flowers and even creating seeds, among other things.

Respiration

Respiration is the process where the sugars created from photosynthesis is used by plants for energy to support life and growth. A few examples include repairing tissues, cell growth and building new tissues.

As such, in a way it’s a bit the opposite of photosynthesis. Photosynthesis creates food while respiration uses the food.

Just as importantly, photosynthesis happens in cells that contain chloroplasts. These include the leaves and green stems. In contrast, respiration happens in all the plants’ cells including the roots.

Finally, respiration happens 24 hours a day, even when the sun isn’t out. That’s not true for photosynthesis.

That said, you can see how the 2 functions work to support plant life and growth. One creates the food source (sugars) the other converts it into energy the plant can use.

Transpiration

Transpiration is the process by which moisture is carried through plants from roots to small pores on the underside of leaves, where it changes to vapor and is released to the atmosphere.

Then, there’s transpiration. Transpiration is the process where water absorbed by the roots is carried up through the plant and released as vapor via the small pores on the underside of the leaves into the air.

This is made possible by the xylem, which is a vascular tissue that runs from the plant’s root tips to the ends of the shoots. Incidentally, it’s this continuous water pressure that keeps plants standing upright.

As such, if a plant loses too much water, it starts to wilt.

Interestingly, 90% of the water a plant absorbs is lost through transpiration. The remaining 10% is used for different functions including transporting minerals and sugars to different parts of the plant and help cool down the plant.

Types of Plants

Now it’s time to get to you the different types of plants better.

Plants can be classified in so many ways. One of the most common ways to do so is by the texture of their stems.

Herbaceous plants are those that have soft, flexible stems.
Woody plants are those that have hard stems.

Herbaceous Plants

The term “bedding plant” can refer to several different kinds of herbaceous plants including annuals, biennials, perennials, and bulbs.

Herbaceous ornamentals are plants that have flexible stems and die back to the ground each year

Unlike woody ornamentals, they do not develop persistent woody tissue that lasts through the winter and develop new buds in the spring

Herbaceous plants are further divided into annuals, biennials and perennials. The distinction between each group is made by how long they live.

Annuals

Annuals go through their entire life cycle in one year. As such, they germinate, grow, flower and produce seed all in one season. Then, they die.

That said, annuals are very popular with homeowners because of their bright colors and lovely appearance. And, since they only live for one season, you’re able to change the look of your garden each year.

The good news is they bloom faster and longer than biennials and perennials. So, you need to make sure to give them space to grow.

Some like a lot of sun while others prefer more shade. Thus, it’s important to position them where they’ll grow best.

Annuals are most beautiful during the summertime then slow down a bit as fall arrives. And, they survive up to around the start of winter before dying.

Their short “lifespan” also means that you should get things right off the bat. Knowing how to grow them before you buy the seeds lets you avoid mistakes.

Also, because you have to replant them each year, they’re less economical compared to biennials and perennials. The good news is, annuals are fairly inexpensive to buy.

Many leafy greens like spinach and lettuce are annuals. Similarly, zinnias and petunias are annuals as well.

Caring for Annuals

One of the best things about annuals is that they’re very easy to care for. They’re tough and can withstand neglect.

But, their growth means that you need to feed them well and give them water. Doing so allows them to maintain their showy exterior.

While it doesn’t sound appealing, deadheading or the process of cutting off flowers that are spent is something you should do to your annuals.

Removing wilting or lackluster flowers helps cut down the energy it expends on these. That way, it can instead focus all that extra energy in making new, more beautiful flowers .

Biennials

As its name suggests, biennials live for 2 years.

In their first season, they grow from seeds into a vegetative plant. As such, you’ll see the roots, stems, and leaves appear during its first year.
In their second season, they flower, produce seeds and later die.

After that, all you’re left with are their seeds. Fortunately, you can replant them.

Cabbage, Swiss chard, celery, parsley, onions and carrots are all examples of biennials. As far as flowers go, you’ve got foxglove, hollyhock, black-eyed Susan, forget me nots, and stock.

Perennials

Perennial plants live for 3 or more years. While they have the longest lifespan of the three, it’s worth noting that they only flower for a few weeks per year.

In most cases, perennials lose their tops (leaves, flowers and stems) when winter comes leaving only their roots. But, they come back and regrow when the next spring arrives.

Perennials are often classified into how hardy they are. In gardening, hardy refers to a plant’s ability to survive the winter.

Here’s a breakdown of the different levels of hardiness according to the Hardy Plant Society in the U.K.

Hardy perennials can get through the winters with temperatures of 5 degrees Fahrenheit (with no protection or very little help from you).
Frost hardy perennials can withstand temperatures that go down as low as 23 degrees Fahrenheit.
Half-hardy perennials can survive mild winters with temperatures not going below 32 degrees Fahrenheit.
Tender perennials are not able to survive temperatures the dip under 41 degrees.

While there isn’t an exact scale like this in the U.S., the figures above should give you a basic idea of how much cold/frost some plants can survive through.

Finally, it’s worth noting that trees, vines and shrubs can be technically included here as perennials. That’s because they live for many years. But, because of their woody stems, gardeners group them separately (as you’ll see below).

Hostas, lavender, aster, hydrangeas and peonies are some examples of perennials.

Woody Plants

In contrast to herbaceous plants, woody plants have hard stems or tough outer skin. These stems often consist of wood, thus, their name.

Similarly, woody plants are unique compared to herbaceous ones since they stay above ground the entire year. In contrast, herbaceous plants die back down into the ground during the winter months.

Finally, because of their firm structure, they’re able to grow taller than herbaceous ornamentals. This allows you to add a vertical aspect to your garden. Their height also allows them to “beat” other plants for sunlight.

Trees, shrubs and vines make up this category. But, it’s important to note that each of them behaves very differently. For example trees and shrubs stand on their own. In contrast, vines rely on other structures for support. This is why you’ll see them covering walls, gates and fences.

It’s also worth noting that just because they have woody stems doesn’t mean that you can’t use them to brighten up your garden. In fact, many flowering woody plants are colorful and fragrant. But, you need to prune and trim them to help them develop properly.

Shrubs

Shrubs are often grown as hedges. But, they’re not limited to that. You can use them as groundcovers, borders as well as for defining your landscape.

Also, shrubs come in many forms, sizes and colors. So, you can use them as focal points or to create areas of interest in your yard, lawn or garden.

For the most part, shrubs grow to as high as 12 feet tall. They’re also foliage dominant. So, you’ll see a lot of greens as well.

Trees

Trees are bigger, taller structures often surpassing 12 feet high. The only exception to this are dwarf trees. Unlike shrubs which have multiple trunks, trees only have one.

But, their trunk is wide and thick. It needs to be so in order to support the branches and leaves above it.

Vines

Unlike trees and shrubs, vines grow on things. More specifically, the climb or cling onto support structures. And over time, they tend to cover that structure with their foliage and flowers.

That said, their vertical nature is what makes them unique.

This allows them to grow on walls, fences, pergolas, arbors and trellises. In doing so, giving you shade from the sun or privacy from your neighbors.

That said, not all vines are the same, even if they somewhat look similar from afar. Their stems vary making them grow on structures in different ways.

Types of Vines

Clinging – These grow on fences, trees and walls easily. They can likewise sneak their way into homes via cracks and crevices which you don’t want.
Twining – These vines wrap their stems on the support structure. They’re also largest group of vines.
Scrambler – These have long stems that weave their way up a structure.
Tendrils – These wrap around structures. Because their stems are short, they tend to choose thinner items to grown against like wires and chain-link fences.