Introduction to Botany 8-1
What is Botany?
Botany is the study of plants. It is divided into many areas including:
|plant taxonomy (identifying, describing and classifying plants)|
|plant geography (the location of certain plants)|
|ecology (studies the relationship between plants and the environment)|
|paleobotany (the study of ancient plants)|
|phytopathology (the study of plant disease)|
|economic botany (how plants can be used as products)|
|plant morphology (the structure of plants)|
|plant physiology (the function of plant parts)|
|plant crytology (the study of plant cells and their parts)|
|plant anatomy and histology (the internal structure of plants )|
As you can see, botany is a very broad subject and one that we can only scratch the surface of in this lesson where our focus will be on an introduction to plant morphology and plant physiology. In Lesson Ten you are introduced to economic botany.
|What makes a Plant "a Plant"?
In the five-kingdom classification system, plants are considered
multi-cellular (having multiple cells) and eukaryotic (having a
membrane around the nucleus of each cell). In addition, plants
have light-absorbing molecules ( chlorophyll) and a number of
cartenoid pigments. Plants store food in the form of carbohy-
drates and their cell walls are made mostly of cellulose.
Plants are necessary for the continuation of life on Earth be-
cause they are an integral part of the food chain, supplying both
energy and oxygen for more complex life forms. Plants are
found everywhere except the polar zones, the highest moun-
tains, the deepest oceans and the driest parts of the deserts.
It is estimated that up to 90% of the living mass on Earth is
made up of plants. There are an estimated 400,000 species of
plants with Columbia, Equador and Peru having more plant
species than any other collection of countries in the world.
The parts of a flowering plant include:
The stem produces and supports new leaves, branches and flowers and keeps these parts in effective positions to receive light, water and warmth. The stem's main function is to transport water and nutrients to and from the roots. In some cases it may also contribute to the reproduction of the plant, store food or help in photosynthesis.
The root of a plant is what anchors the plant in the soil and absorbs nutrients and water. In hydroponics, the root mainly serves only to absorb the nutrients and water we feed them. Roots range from a single large root, the tap root, to a mass of smaller, similar sized roots. The roots penetrate the soil or growing medium by cell division and elongation of the cells just behind the tip.
In a hydroponic growing system, the plant's root system will be much smaller than if it were grown in soil. Since the purpose of the roots are to seek out and absorb the nutrients and water and a hydroponic solution provides exactly what the roots are looking for, they do not need to develop an extensive root system.
As we learned in Lesson Seven, leaves are the plant's means of intercepting light, obtaining and storing water and food, exchanging gases and providing a site for photosynthesis.
The flower of a flowering plant is the sexual reproduction unit that produces and houses the sex cells (gametes). Flowers also attract pollinators (e.g. insects and birds) that carry pollen from the stamen and fertilize other plants.
The fruit aids in the dispersion of the plant's seeds. After
fertilization, the ovary begins to develop into a fruit, the
ovules into seeds. The seeds are carried off and will, if con-
ditions are right, eventually germinate and start a new plant.
Seeds are dispersed in several different ways: Light seeds,
such as dandelions, can be carried by the wind. Birds are
attracted to some fruits and, after eating the fruit, leave seeds
in their droppings. Some seeds are barbed and easily stick
to unsuspecting passersby (usually animals). Eventually,
the seed is scratched off or falls off. Some seeds will drop
from the plant in a high wind or when shaken.
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