Introduction to botany

Introduction:

Before studying this science, we should answer several of logical questions that come to the mind of each student, who studying one of the disciplines which botany is its essential, such as medicine, agronomy, agricultural engineering and some other disciplines.

The most important of these questions are:

1. What organisms are scientifically considered as plants?


2. Why should we study botany?


3. What is the importance of botany for my major?


4. What are the botany studies and what are the scientific foundations of this science?

Pupils are taught in a biology lesson that plants are living organisms that self-feeding produce their own food through the process of photosynthesis.

This is confirmed by some of the most important dictionaries of  English language where the plant is defined according to Collins Dictionary as a is a living thing that grows in the earth and has a stem, leaves, and roots.

While the Cambridge Dictionary defines a plant as a living thing that grows in earth, in water, or on other plants, usually has a stem, leaves, roots, and flowers, and produces seeds.

It may be one of the most simplified definitions of plants that should be mentioned in an introduction to botany, and it is “one extremely important concept to understand: plants are not animals! Obviously, this phrase has many important meanings.

First of all, it is much easier for us to understand animal life than plant life. Many terms that are associated with animal life (like “stomach” or “blood pressure”) are generally well known, even intuitively.

Learning botany as a beginner requires to speak about plants, and to speak, you have to learn botanical language. This is why you need to know a vast amount of terms, so be prepared to work hard.”

All living things were traditionally placed into one of two groups, plants and animals. This classification may date from Aristotle (384 BC – 322 BC), who made the distinction between plants, which generally do not move, and animals, which often are mobile to catch their food.

Much later, when Linnaeus (1707–1778) created the basis of the modern system of scientific classification, these two groups became the kingdoms Vegetabilia (later Metaphyta or Plantae) and Animalia (also called Metazoa).

Since then, it has become clear that the plant kingdom as originally defined included several unrelated groups, and the fungi and several groups of algae were removed to new kingdoms. However, these organisms are still often considered plants, particularly in popular contexts.

The term "plant" generally implies the possession of the following traits: multicellularity, possession of cell walls containing cellulose, and the ability to carry out photosynthesis with primary chloroplasts.

The above definition of plants or plant kingdom can be explained by the following Plants can be divided into two groups: plants1 and plants2:

Plants1 contain all photosynthetic organisms which use light, H2O, and CO2 to make organic compounds and O2. Plants1 are defined ecologically (based on their role in nature).

Plants2 are all organisms from Vegetabilia kingdom. Normally, plants2 are green organisms with a stem and leaves. We can define them also as multi-tissued, terrestrial, and primarily photosynthetic eukaryotes. This definition is taxonomical (based on evolution).

And it could be so surprising when a student discovers that Some plants1 can be bacteria or even animals! And it could be unbelievable even when a factual example will be provided.

Green slugs collect chloroplasts from algae and use them for their entire life as food producers. Therefore, green slugs are both animals and plants1. See the photo above

Now after such an amazing example it would be normal to ask "which plant can be in plant2 but not plant1?”

Here the answer can be easier to be acceptable as a lot of common plants could be mentioned like those which fall into that category, are fully parasitic plants, which do not practice photosynthesis but have tissues, terrestrial lifestyle and originated from photosynthetic ancestors like: dodder or strangle tare, Cuscuta.

Dodder can be identified by its thin stems appearing leafless, with the leaves reduced to minute scales. From mid-summer to early autumn, the vines can produce small fruit that take the same color as the vine. It has very low levels of chlorophyll; some species such as Cuscuta reflexa can photosynthesize slightly, while others such as C. europaea are entirely dependent on the host plants for nutrition.

We have seen that the definition of plant was evolving according to the evolution of human knowledge, but what were the motives of man to study plants?

Botany originated in prehistoric times as herbalism because of the early efforts of humans to identify edible, medicinal and poisonous plants and then cultivate them in later eras, making it one of the oldest branches of science.

Just as botany derives its importance by meeting the human needs for food and medicine, this importance of botanical research has expanded to include has diverse applications:

• in providing staple foods, materials such as timber, oil, rubber, fibre and drugs;


• in modern horticulture, agriculture and forestry, plant propagation, breeding and genetic modification;


• in the synthesis of chemicals and raw materials for construction and energy production;


• in environmental management, and the maintenance of biodiversity.

All of this information can be summarized on key points

• Plants are mainly multicellular, predominantly photosynthetic eukaryotes of the kingdom Plantae.


• Historically, plants were treated as one of two kingdoms including all living things that were not animals, and all algae and fungi were treated as plants.


• All current definitions of Plantae exclude the fungi and some algae, as well as the prokaryotes (the archaea and bacteria).


• By one definition, plants form the clade Viridiplantae (Latin name for "green plants"), a group that includes the flowering plants, conifers and other gymnosperms, ferns and their allies, hornworts, liverworts, mosses and the green algae, but excludes the red and brown algae.

This brief overview of botany and some of its applications in practical life will serve as a roadmap that we will return to understand the noble purpose of this science and the lofty goals of all those who study it.We will examine in details about the basics as well as the principles and foundations of botany at a later article.