Subkingdom: Tracheobionta (Vascular plants)
Non-vascular plants (bryophytes)
Plants comprise a major group of multicellular eukaryotic organisms, known as the Kingdom Plantae. All plants were created on the 3rd day of creation, including familiar types such as trees, herbs, flowers, and ferns. Botany is the field of biology dedicated to studying plant structure, function, and growth requirements.
The importance of plants, and therefore of our understanding of them, cannot be overstated. They are an integral part of the Earth's ecosystem, and without them life as we know it would not be possible. Plants are known as autotrophs, or producers, because they make their own food through photosynthesis, and consequently serve as the ultimate source of chemical energy for the rest of the food chain.
Origin of plants
The evolutionary model holds that plants evolved from primitive green algae some 400 million years ago. No "first plant" or "last algae" have been proposed. No explanation has been made for how algae gained the ability to take root on land, nor how they developed the ability to develop from embryos. These abilities are remarkably complex, and would have required a great number of mutations in order to function at all. Evolutionists have not explained the origin of these unique characteristics, other than to assert that it occurred.
The evolutionary model for the origin of plants is rife with problems. Perhaps the most difficult problem is the problem of abiogenesis and ozone, or the fact that plants are necessary to produce oxygen, but could not survive if the atmosphere did not already have oxygen and ozone to protect them from ultraviolet radiation.
Creation of plants
The Bible states that all types of plants were created on the 3rd day of creation; even before the sun was created. This sequence of events seems to directly contradict an interpretation of the "days" of creation as long periods of time. It is emphatically stated by God that the purpose of plants is to be food for humankind and "all" animals.
Genesis 1:11-13 reports the creation of plants on the 3rd day.
Then God said, "Let the land produce vegetation: seed-bearing plants and trees on the land that bear fruit with seed in it, according to their various kinds." And it was so. 12 The land produced vegetation: plants bearing seed according to their kinds and trees bearing fruit with seed in it according to their kinds. And God saw that it was good. 13 And there was evening, and there was morning—the third day. Genesis 1:11-13 (NIV)
Genesis 1:29-30 reports that plants were to be food for humankind and "all" animals.
Then God said, "I give you every seed-bearing plant on the face of the whole earth and every tree that has fruit with seed in it. They will be yours for food. And to all the beasts of the earth and all the birds of the air and all the creatures that move on the ground—everything that has the breath of life in it—I give every green plant for food." Genesis 1:29-30 (NIV)
Genesis 2:9 reports that plants also serve an ornamental function.
And the LORD God made all kinds of trees grow out of the ground—trees that were pleasing to the eye and good for food. Genesis 2:9 (NIV)
- Main Article: Photosynthesis
Within an ecosystem, plants are known as producers. They perform the immensely important biochemical reaction known as photosynthesis, which produces the chemical potential energy (carbohydrates) that almost all other organisms on Earth are reliant upon. In addition to producing carbohydrates, oxygen is another important by-product of photosynthesis. Oxygen is equally important and required by organisms for the process of aerobic cellular respiration.
Humans and many kinds of animal derive much of their basic daily energy from the cereal crops (wheat, rice, corn). Fruits (plant ovaries) and vegetables (vegetative growth) from the flowering plants also fulfill a significant portion of the energy requirements of many consumers. In addition to supplying basic nutritional needs, the woody portions of plants have also served humanity as a building material, and fuel source for many activities such as cooking, heating, and lighting.
Photosynthesis is the chemical synthesis of complex organic materials, especially carbohydrates, from carbon dioxide and water using sunlight as the source of energy and with the aid of associated pigments. Photosynthesis seems only able to occur when there is energy from light from a star such as our Sun; the proper atmosphere, the proper amount of water vapor and organisms equipped with biological function to harvest it on Earth.
For most organisms on Earth, photosynthesis is the beginning of the food chain. Photosynthesis enables plants to produce food for themselves, which is then ultimately passed on to animals and microbial organisms when they are eaten. Because plants make their own food, they are called producers (autotrophs), as opposed to animals which are consumers (heterotrophs).
In simple terms, photosynthesis is the process where atoms of carbon are hydrated (carbo-hydrate). With some minor variation, the ratio of Carbon to Water in carbohydrates is (1Carbon : 1H20). For example, glucose has the chemical formula C6H1206, which is 6(C+H20).
- Main Article: Plant reproduction
All plants have an alternative life cycle called the alternation of generations. One portion of the lifecycle is known as the sporophyte stage. This stage produces spores and is always genetically diploid (having 2 of each homologous chromosome). The other portion is known as the gametophyte stage, which produces gametes (sex cells) and is always haploid (having 1 of each). The sporophyte stage is larger and most conspicuous in ferns, whereas the gametophyte is dominant in mosses.
Plants can propagate through both sexual and asexual methods known as vegetative reproduction. Many plants can generate a genetic clone through a process called vegetative reproduction, which does not involve meiosis, gamete formation, or fertilization. This type of propagation involves the development of shoots and roots from a number of tissues such as stems, roots, and leaves. Many crops, grasses, and trees are developed using this type of cloning instead of by seed. Examples include Potatoes, Bananas, Aspen, Poplar, Willow, Strawberry, Avocado, Fig, Pineapple, citrus fruits (Lemon, Orange, Grapefruit), nut crops (Walnut, Pecan), and some fruits (Apple, Pear).
In angiosperms, sexual reproduction begins through pollination. Pollination happens when the pollen (male gamete) comes in contact with the stigma (female organ) of the same or a different flower. Pollen transport is accomplished either by drifting in the wind or being carried to another flower by insects, such as bees. After pollination, the pollen grain germinates and begins to grow a pollen tube down the style, through the wall of the ovary and into an ovule (incipient seed). As the pollen tube grows, two sperm are produced - one unites with female gamete, the other unites with the central cell of the ovule and produces the endosperm of the seed.
Unlike most animals and humans, plants continue to grow as long as they live. They can also be defined as functionally immortal. Although many have adapted to annual lifecycles where necessary, all types of plants grow as perennials where conditions allow, and only die as a result of trauma, pathogenicity, or when their basic requirements for life are not met.
Plants have the unique ability to grow in specific directions as a response to a number of external stimuli (tropism). This phenomenon is known as a tropism, which can be a positive or negative growth. For example, the response of plants to gravity (geotropism), is positive/toward the stimulus in roots, and negative in the stems where growth is in the opposite direction. Plant shoots are stimulated to grow toward sunlight (phototropism). Hydrotropism is a response to water, chemotropism to a chemical stimulus, and thigmotropism is a response to physical contact, which causes tendrils of climbing plants to grow when they touch a support and then grow around it.
- Main Article: Cell biology
Although similar in many ways, the plant cell differs significantly from animal cells. Most notable perhaps is the organelle known as the chloroplast that performs the extremely important process of photosynthesis. The chloroplast has pigments, such as chlorophyll, which capture sunlight and give plants their characteristic green color.
Plant cells also differ in a number of ways due to design features related to structural support. The shape of the plant cell tends to be square, which serves the same function as building blocks to an architect. The cell is also reinforced with a very durable cell wall made of plant fiber known as cellulose. The plant cell also contains an enlarged storage vacuole, which also provides support through turgor pressure.
- Main Article: Paleobotany
Paleobotany is the field of paleontology involved with the study of ancient plants. It is an important area of creation biology, as creationism and evolutionism have radically different descriptions of ancient plant life. Creationism holds that a wide variety of plant life was created by God fully intact with the capacity to reproduce and adapt to changing environments, approximately 6,000 years ago. Evolutionism holds that all plant life (and indeed all life on the planet) is related by common descent over millions of years, and that more complex plants developed more recently than simpler plants.
The Kingdom Plantae or plant kingdom includes the Mosses, Ferns, Flowering plants, and Conifers. Instead of phyla, the plant kingdom is broken down into "divisions". The division of the Embryophytes or land plants is listed below.
Vascular plants (Tracheophytes)
- Seedless Vascular Plants
- Lycopodiophyta - Small plants with green, branched stems, scale-like leaves, and no flowers. Usually grow very low to the ground. Includes: Club Mosses, Quillworts, and Spikemosses.
- Equisetophyta - horsetails
- Pteridophyta - "True ferns" Plants that have roots and stems, but do not have flowers or seeds. Instead, they spread with spores. Includes Ferns.
- Psilotophyta - whisk ferns
- Ophioglossophyta - adderstongues
- Seed plants (Spermatophytes)
- Magnoliophyta - (Anthophyta) - The "flowering" plants.
- Pteridospermatophyta - extinct seed fern
Non-vascular plants (Bryophytes)
- Hepatophyta - (AKA Marchantiophyta) - liverworts
- Anthocerotophyta - hornworts
- Bryophyta: Plants with very small leaves and stems, with no roots and no flowers. Usually grow very low to the ground. Includes: Mosses.
- Chlorophyta -- green algae
- "Photosynthesis Requires the Right Kind of Star." Creation-Evolution Headlines, July 27, 2007. Accessed August 30, 2008.