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THE ORIGIN OF KINGDOM PLANTAE PROPONENT:SHAYNE ANNE C. DE GUZMAN SHANIA MLEN FONTANALGO DIVINA ROSE D. RAON REYNALD REA MATTHEW REYES AFFILIATION: THE GREAT PLEBEIAN COLLEGE INTRODUCTION: Plants (land plants, embryophytes) are of monophyletic origin from a freshwater ancestor that, if still extant, would be classified among the charophycean green algae. Plants, but not charophyceans, possess a life history involving alternation of two morphologically distinct developmentally associated bodies, sporophyte and gametophyte. Body plan evolution in plants has involved fundamental changes in the forms of both gametophyte and sporophyte and the evolutionary origin of regulatory systems that generate different body plans in sporophytes and gametophytes of the same species. Comparative analysis, based on molecular phylogenetic information, identifies fundamental body plan features that originated during radiation of charophycean algae and were inherited by plants. These include, in probable evolutionary order: cellulosic cell wall, multicellular body, cytokinetic phragmoplast, plasmodesmata, apical meristematic cell, apical cell proliferation (branching), three-dimensional tissues, asymmetric cell division, cell specialization capacity, zygote retention, and placenta. Body plan features whose origin is linked to the dawn of plants include: multicellular sporophyte body, histogenetic apical meristem in the gametophyte body, and capacity for tissue differentiation in both sporophyte and gametophyte. Origin of a well-defined sporophytic apical stem cell and a system for its proliferation, correlated with capacity for organ production and branching, occurred sometime between the divergence of modern bryophytes and vascular plant lineages. Roots and their meristem and a multilayered tunica-corpus shoot apical meristem arose later. Regulatory genes affecting shoot meristems, which have been detected by analysis of higher plant mutants, may be relevant to understanding early plant body plan transitions. The chloroplasts of green plants are surrounded by two membranes, supporting the theory of an endosymbiosis, with cyanobacteria a common ancestor. Embryophytes descended from green algae during the Palaeozoic era, and are also called the land plants (though some live in water) and include all the trees, flowers, ferns, mosses with which we are all familiar. All are complex multicellular organisms with specialized reproductive organs and, with rare exception, use photosynthesis for their energy. For some 1.5 billion years, photosynthetic organisms remained in the sea, protected from ultraviolent radiation. The earliest photosynthetic organisms to invade land probably resembled modern algae, cyanobacteria, and lichens, and were followed by the bryophyte, including liverworts (Division Marchantiophyta) and mosses (Division Bryophyta) that descended from the charophyte group of green algae.

METHODOLOGY: From Aristotle to Lamarck This evolutionary worldview was put on hold by the theories of the great Greek philosopher Aristotle (384-322 B. C. E.) and by his famous student Theophrastus (c. 372-287 B. C. E.), who is regarded as the father of scientific botany. They believed in a fixed or static universe, which saw all plants and animals as falling into discrete types or kinds organized in a well-defined, hierarchical scheme from lower to higher organisms. Aristotle called this organization of life, the scala naturae, or the ladder of creation. This view dominated natural philosophy and reached its fullest expression with the work of the great Swedish taxonomist, Carolus Linnaeus (1707-1778). His reform of the taxonomic system was built on the idea that organisms such as plants fall into well-defined types. The Linnaean system follows this typological or essentialistic approach to the natural world by adhering to the notion of the ideal type. This is seen in the pivotal taxonomic use of the type specimen , the technical taxonomic term for the first species of a new group described. The return to a changing vision of life accompanied the new geological theories of the eighteenth century. These new theories were fueled by new fossil discoveries and the establishment of the view that fossils are organic in nature; that is, that they were remnants of once-living organisms. Plant fossils figured prominently in this. Geological theories were also informed by the revolutionary beliefs associated with the Enlightenment , especially the idea of progress. This idea implied a directionality to history and suggested that progress was in the natural order of things. It also suggested that the world, and Earth, were much older than previously thought, especially as revealed by Biblical scripture. Combined with developments in the comparatively new morphology of both plants and animals and the staggering diversity of new specimens of plants and animals flooding Europe from the voyages of discovery, the new geological theories began to uphold the view that Earth changed in a slow, gradual manner. Instead of accepting the view of unique, one-time, or catastrophic events—such as the flood of Noah—the view that uniform geological processes were responsible for creating Earth, or uniformitarianism, began to dominate geology. Soon, naturalists began to challenge the notion of the fixity of species as they realized that Earth itself was undergoing constant but uniform change. The French naturalist Comte Georges-Louis Leclerc de Buffon (1707-1788), a contemporary of Linnaeus, was one of the first to suggest a transmutationist theory for living organisms. He made a famous speculative statement applying his belief in a constantly changing Earth to living organisms in volume three of his great compendium of the natural history of Earth, Histoire naturelle (1749-67).

This statement paved the way for the first coherent transmutationist theory formulated by Jean Baptiste Lamarck (1744-1829), a botanist of some repute, and the first person to use the word "biology." This theory was clearly formulated in his Philosophie zoologique (1809). Despite its zoological title, the book drew on insights Lamarck had gleaned from his botanical background to explain the phenomenon of adaptation in all living organisms. According to Lamarck, favorable adaptations were originated by the effect of the environment acting directly on the organism. Lamarck therefore mistakenly thought that the environment directly induces permanent change in the genetic composition of organisms. This was what he meant by the "inheritance of acquired characters." The phenomenon of use and disuse, also associated with Lamarck, stated that prolonged use of an organ led to its modification, and disuse led to its elimination. Although Lamarck's theory was widely discussed and became especially popular in his native France, it did not provide a mechanism for how the environment induced such permanent modification, nor did it provide good scientific evidence. Darwin, Mendel, and the Evolutionary Synthesis These inadequacies were addressed by the individual who is most closely associated with the theory of organic evolution, Charles Darwin (1809-1882). Darwin did not explicitly reject Lamarck's explanation for adaptation, but instead suggested another mechanism he called natural selection. This was the process by which organisms with favorable variations survived to reproduce those favorable variations. Given enough time, he argued, subsequent generations would depart from the parental type under the action of selection until they formed a new species. This principle of divergence supported and strengthened what Darwin formally called his "theory of descent with modification." This theory was set forth in On the Origin of Species (1859). Darwin drew heavily on examples from the distribution of plants and on knowledge of plant breeding to formulate his theory. In the last twenty years of his life, he studied the phenomenon of adaptation in plants such as orchids, which had evolved spectacular contrivances by which to attract pollinators such as bees. Plants were in fact to provide Darwin with some of the best evidence in support of his theory. Darwin's theory of evolution transformed understanding of the origins of all life on planet Earth. Botanists such as Joseph Dalton Hooker (1817-1911) in England and Asa Gray (18101888) in the United States grew to accept and apply Darwinian evolution to the plant kingdom and to promote the theory further. Despite its success, a considerable number of botanists continued to uphold Lamarckian notions well into the twentieth century. One reason for this is that it is especially hard to distinguish between genotypical variation (variation due to genetics), and phenotypical variation (variation as the result of a direct response to the environment). Unlike animals, which have closed developmental systems, plants have open or indeterminate developmental systems that permit them to continue to "grow" and generate new tissue in regions such as the shoot and root. Plants are thus able to demonstrate the phenomenon of phenotypic plasticity, the ability to adapt readily to new environments and to generate especially complex variation patterns that appear to support Lamarckian inheritance.

It took the work of the geneticists such as Gregor Mendel (1822-1884), who formulated the modern theory of heredity, and Wilhelm Johansen (1857-1927), who first drew the distinction between phenotype and geno-type, to begin to understand more complex aspects of plant evolution, such as plant speciation . It was not until 1950, however, that botanists were able to finally integrate Darwinian natural selection theory with Mendelian genetics, and finally dispelled notions of Lamarckian inheritance. Modern ideas of plant evolution and the science that is framed by the subject, plant evolutionary biology, appeared with the publication of Variation and Evolution in Plants (1950), by the American botanist George Ledyard Stebbins Jr. (1906-2000). With its appearance, botany and plant evolution are generally thought to have become part of the historical event termed "the evolutionary synthesis." This event finally saw the establishment of Darwinian evolution by means of natural selection synthesized with Mendelian genetics. It remains the overarching theoretical framework for explaining the evolution of plants. RESULT AND DISCUSSION: Kingdom Plantae classification, systematics and phylogeny are not settled science, and the tree of life for plants has undergone major revisions in recent years. There are many competing views and hypotheses, with more revisions the assured outcome. Unraveling the mysteries of plant evolution is being made possible by now very inexpensive molecular whole genome sequencing across the plant Kingdom. The history of plant life is all pretty confusing, so we've tried to condense it in the table below, and provide succinct supporting summaries in the table notes.

Unranked Groups or Subkingdoms Green Algae (Fomerly in now obsolete Kingdom Protista - see note 2) Unranked Embryophytes (Land Plants) - Bryophytes (Non-Vascular plants) see note 1

Division Chlorophyta Charophyta Marchantiophyta - liverworts Anthocerotophyta - hornworts Bryophyta - mosses Horneophytopsida

Unranked Non-seed-bearing plants Tracheophytes (Vascular Plants -

Rhyniophyta - rhyniophytes Zosterophyllophyta - zosterophylls Lycopodiophyta - clubmosses

Trimerophytophyta trimerophytes Pteridophyta - true ferns and horsetails Progymnospermophyta - whisk ferns Gymnosperm (note 4)

Pteridospermatophyta - seed ferns Pinophyta - conifers

note 2)

Gymnosperms Cycadophyta - cycads Unranked Gymnospermae Spermatophytes (notes 4 and 5) Ginkgophyta - ginkgo (seed plants - note Gnetophyta - gnetae 3) Angiosperms flowering Magnoliophyta - flowering plants (also plants (notes 4 called angiosperms, angiospermopsida) and 5)

The origin of the term "morphology" is generally attributed to Johann Wolfgang von Goethe (1749–1832). He was of the opinion that there is an underlying fundamental organisation (Bauplan) in the diversity of flowering plants. In his book The Metamorphosis of Plants, he proposed that the Bauplan enabled us to predict the forms of plants that had not yet been discovered.[4] Goethe also was the first to make the perceptive suggestion that flowers consist of modified leaves. The past century witnessed a rapid progress in the study of plant anatomy. The focus shifted from the population level to more reductionist levels. While the first half of the century saw expansion in developmental knowledge at the tissue and the organ level, in the latter half, especially since the 1990s, there has also been a strong impetus on gaining molecular information.

Evolution of Plants: Eukaryotes further diversified to form green algae and early invertebrates. The first organisms that existed on land were plants. Bryophytes were the first plants to colonise lands. Fossils in good number are found from Palaeozoic era. Middle Palaeozoic is also called “age of algae”. Late Palaeozoic is called “age of ferns”. All algal groups became established during Cambrian period. First land plants (Psilophytes) originated in Ordovician period. Marine algae were abundant in Ordovician period. Earliest spore-bearing plants were developed in Silurian period. Origin of vascular plants (Gymnosperms and Angiosperms) took place in this period. It is also period of origin of ferns.

Herbaceous Lycopods (ferns) and Aborescent lycopods (ferns) evolved from Zosterophyllum of Palaeozoic era. Psilophyton is the common ancestor for horsetails, ferns and gymnosperms. Devonion. Earliest mosses an ferns. Carboniferous — Abundance of tree ferns forming coal forests. First seed plants appeared. Mesozoic era. Also called age of gymnosperms. Permian — Origin of Conifers. Triassic — Abundance of ferns, cycads and conifers. Jurassic — Age of cycads (they were in abundance). Origin of angiosperms also took place in this period. Ferns and gymnosperms began to decline during cretaceous period. There was dominance of flowering plants. Tertiary period is also called age of angiosperms. Quaternary period is similarly known as the age of herbs. Eocene — Angiosperm dominance increases. Oligocene — Rise of monocots. Miocene — Adaptive radiation of angiosperms. Pliocene — Adaptive radiation of flowering plants. Holocene — Development and rise of herbs, decline of woody plants. Evolution claims that plants descended from algae as they colonized the empty landmass. Plants couldn’t have evolved until there was a sufficient ozone layer to block radiation. The many structures that plants require in order to overcome gravity, keep from drying out, and reproduce would have to have developed gradually over millions of years. Molecular and fossil evidence has complicated the evolutionary model that explains how plants evolved from simple to complex forms. The simple groups are evolutionary dead ends; so plants must have evolved simultaneously in several different ways. Seed plants are alleged to have had an advantage over other ancient plants, and they dominated the landscape. The ancient forests are the source for the different coal beds in evolutionary theory. Flowering plants were the most recent to appear since leaves were remodeled to attract pollinators and accomplish reproductive functions.

Despite this evolutionary story, the Bible describes the creation of different kinds of plants in Genesis 1. The presence of “living fossil” plants like the Gingko biloba tree makes it clear that evolution is a plastic theory that can accommodate both rapid change and stability for hundreds of millions of years. The creation of plants in their many diverse forms is apparent in the intricate design of plant systems and the symbiotic relationships that could not have evolved in a gradual process. In the evolutionary story, plants arrived relatively late in earth history. The first fossils of plants are supposed to be 475 million years old. Evolutionists generally agree that plants evolved from algae that slowly began to colonize the land. This could not have occurred until after there was an intact ozone layer to protect the plants from some of the atmosphere’s harmful UV rays. Since this was an alien land, plants had to adapt to the new landscape. Several key systems had to be developed to prevent drying out (desiccation) in the air, to absorb nutrients from the soil, to grow upright without the support of water, and to reproduce on land. All of these new features required new information to code for their production. As stated previously, no mechanism can consistently provide new information from random mutations in the genomes of individuals. While plants do have many adaptations that allow them to be successful on land, these features could not have developed through evolution. The many features that allow plants to thrive in diverse environments were programmed into the different plant kinds when they were created by God. This view of adaptation is a key difference in the evolution and creation models. Setting aside evolutionary bias and focusing on operational science, we can define adaptation as: In evolutionary biology, adaptations are often acquired by modifying existing structures to accomplish new tasks. In the case of algae turning into plants, the preexisting structures are mostly absent. Few algae have differentiated tissues that could be adapted to a new use. To get around this, some suggest that fungi invaded the land with the plants to help in absorbing nutrients from the soil. There is much evidence of plants and fungi living in symbiotic relationships today, but nothing to suggest that they evolved to help one another. The first plants to evolve were the small mosses and liverworts (bryophytes), but these evolutionary dead ends did not lead to the vas cular plants that are common today. The three groups of bryophytes are found in an unexpected sequence in the fossil record, so evolutionists must accept that they evolved separately from one another. The most likely ancestor is a mobile alga known as a “chlorophyte.” The adaptations shown in this figure allegedly developed over millions of years as plants had to acquire new features to be able to survive on land. Superficially, similarities between the algae and plant are shown, but the information required to produce the new structures and their functions cannot be explained within the evolutionary framework. Each of these groups was created with the features and information they need to survive in the conditions in which they live. The vascular plants are supposed to have evolved separately from other algae. The ferns, club mosses, and horsetails (pteridophytes) are the suggested common ancestors to the vascular plants that are present in large quantities today. The Carboniferous era is described as having giant ferns and club moss trees, none of which survives today. The vast forests of the Carboniferous are the source of many coal and oil reserves in the evolutionary model. The next step in the evolutionary story is the development of seed plants. The first to evolve were the gymnosperms, cone-bearing plants like conifers, ginkgo, and cycads. These plants had an adaptive advantage over the pteridophytes and dominated the forests of the late Paleozoic era.

Another problem facing the evolutionary story is the presence of fossil plants that have not changed in hundreds of millions of years. The species Ginkgo biloba is known from fossils that are supposed to be 200 million years old. Another “living fossil,” the Wollemi pine, was recently discovered in Australia. The oldest fossils of this plant date to over 90 million years. The plastic theory of evolution must accept that these plants are evidence that evolutionary forces can act by holding still for millions of years, even though evolution can explain the rapid appearance of new species. RECOMMENDATION: