Plant Phylogenetic Description

Plant Phylogenetic Description

• 1.
  Diversity of Life TheKingdom of Plants King Chloroplast Major Groups: Extant phyla within the kingdom Plantae
• 2.
  A. Non-vascular plants (bryophytes) 1. Marchantiophyta - liverworts 2. Anthocerotophyta- hornworts 3. Bryophyta - mosses B. Vascular plants (tracheophytes) 1. Lycopodiophyta - clubmosses 2. Equisetophyta - horsetails 3. Pteridophyta - "true" ferns 4. Psilotophyta - whisk ferns 5. Ophioglossophyta - adderstongues 6. Seed plants (spermatophytes) a) Pinophyta - conifers b) Cycadophyta - cycads c) Ginkgophyta–ginkgo d) Gnetophyta - gnetae e) Magnoliophyta - flowering plants Mosses and their allies,liverworts and hornworts, are the oldest land plants in the world. These plants are all non-vascular, meaning they have no tissue for transporting water and nutrient thought the cell. Their spoors must be transported and united into diploid cells by an outside water source flowing through the plant. Nutrients must be distributed the same way, with each piece of the plant relying on the luck to have nutrients be washed its way. Non vascular plants are thus limited to a small size, as each cell can only obtain nutrition a direct neighbor cell diffusing some or by water flowing over it. Because of this, the non-vascular plants are only able to colonize places where water flows regularly.
• 3.
  Marchantiophytais the nameof the liverwort phylum. These are possibly the oldest land plants in the world, and, together with hornworts, are the most primitive plants to be found today. There are two classes of liverworts, Jungermanniidea(leafy) andMarchantiopsida(leaf-like). The leafy liverworts in the first generation (gametophyte) look very like mosses. Leaf-like liverworts in the first generation look like plump leaves. The spoors, rather than being produced on the end of a thin stalk like leafy liverworts, are produced on the underside of an umbrella shape on the end of a thick stalk (thecarpocephalum). Anthocerotophyta is the name of the hornwort phylum.These may also be the oldest land plants in the world. There is only one class in the phylum Anthocerotophyta, it is Anthocerotae which has but one order, Anthocerotales .Hornwort cells are notable because, unlike other land plants, their cells contain only one large chloroplast each. Hornwort sporophyte generations manifest themselves inside, rather than on, the green central stalk, which splits open upon maturity to release the spoors. Bryophyta is the name of the moss phylum. While hornworts and liverworts are only distantly related to all other plants, mosses are probably the ancestors of most land plants. Though still primitive, being non vascular, mosses are less primitive and more diverse than either liverworts or hornworts and have a central support on their leaves. This midrib may be the predecessor to stalks in vascular plants. The sporophyte of a moss is a long stalk with a capsule on the end. The sporophyte grows parasitically on the gamete generation until it reaches maturity, upon which it splits open and releases the spoors. The stalk may remain for some time after that. There are three classes in the Moss phylum: Peat Mosses (Sphagnopsida), Granite Mosses (Andreaopsida), and true mosses (Bryopsidia). Peat mosses are often found in bogs and have historically been burned for fuel. Ferns and their allies (club mosses, horsetails, whip ferns, and adderstounges) are the next generation of plants, and the next line of attack against rocks. They are the first vascular plants, meaning they have developed specialized tissues for water and nutrition transport (roots, stems, leaves). They also develop firm tissues for structural support. All of these together allow early vascular plants to reach hithertounknownheights; literally, as some can grow to the sizes of small trees, and so monopolize more sunlight. Roots allow the plant to survive when water is not running directly over all parts of the plant. If one root is in a sufficiently wet place, it can, distribute the water to all other parts of the plant. However, the spoors of ferns and their allies rely on water in the same way moss spoors do, requiring the luck for water to run in exactly the right place at the right time for fertilization to occur. Because of this, plants were still limited to wet places through which water regularly ran.
• 4.
  Psilotophyta is thename of the whisk fern phylum. Whisk ferns are notable because, although they contain vascular stems, they lack roots. Instead, their stems are simply buried in the ground. Whisk ferns are dichotomous, meaning they branch off in pairs. Taxonomy accidentally mirroring physiology, there are two genera (only one class, order, and family) within the phylum, Psilotum andTmesipteris. Psilotumis the more primitive of the two, and perhaps the most primitive of vascular plants to be seen today, because it lacks leaves as well as roots, instead having proto-leaf extensions of the stem called enations. However, Tmesipteris’s gametophyte generation has no vascular tissue, so Psilotum appears more advanced until the sporophyte stage. Lycopoidiophyta is the club moss phylum. It is the oldest living phylum of vascular plants, having fossils dating to 420 Megayears ago. This phylum is notable because although it does not contain true leaves, but photosynthetic elongations of the stem called enations, each enations has a vascular trace (capillary). In this way, the club moss phylum links the primitive whisk ferns and true ferns as the vascular system extends and develops, the leaf being the next logical step from vascularized enations. In addition to paving the way for leaves, these plants assist human society in a financial way, as many of these plants fossilized into what are now coal mines. Their spores are used in fireworks. Equisetophyta is the name of the Horse Tail Phylum. The horse tail phylum evolved aporximately 400 million years ago, and became very important by the 300-250 Megayear ago mark. Horsetails are significant because they demonstrate the gradual evolution of leaves. Horsetail leaves are true leaves, with true vascular systems, but the leaves are not yet evolved to be fully and gracefully extended on the plant, leaving the plant with small, but true leaves, thereby linking the morphic chain from moss to fern completely. Species in this genus such as the E. arvensecan regrow from seemingly nothing, having been dug up by the roots, because horsetail gametophytes are buried so far into the ground. In the Carboniferous period, horsetails were big, in two ways, once they covered almost all the world but Australia, and two and they could grow up to 30 meters (90 ft) tall. Since the rise of seed plants, however, horsetails have suffered. There is now only one continuing class of horsetail left , Equisetopsida, in it a one extant order, Equisetales , in that a lone living family, Equisetaceae, which shelters the sole surviving genus, Equisetum , which contains a mere fifteen species. Horsetails are therefore, considered living fossils, but that doesn’t stop them getting weeded out of gardens across the old world. Pteridophyta is the name of the fern phylum. Ferns first appeared 350-250 Megayears ago.Since then ferns have evolved into a total of 20,000 species, divided into four classes: Psilotopsida, Equisetopsida, Marattiopsida, andPolypodiopsida, the former being the stereotypical fern most people associate with the name. These thousands of species have been busy evolving into many specialized nieces, from banks of rainforest ponds to sheer, dry desert rocks, ferns can be found, despite early plants’ noted difficulties in that area. The gametophyte stage of the fern is very hard to find, for it is just a small heart-shaped green leaflet. It is the sporophyte that one imagines when they hear the word “fern.” Fern sporophytes sprout up into fronds (fern-shaped leaves) that shelter spores on their underside and can grow as tall as trees.
• 5.
  Ophioglossophyta is thename of the adderstongue, moonwort, and grape-fern phylum. Until recently, adderstongue were thought to be ferns, but gradually biologists have realized that adderstongue and allies are individual. However, dispute continues. While the currently winning viewpoint gives adderstongueand allies their own phylum, there is another scheme which groups adderstounges, whisk fern, and horsetails as classes in a single phylum, Archeophyta. This phylum, unlike ferns, has underground gametophytes and fleshy roots. In some species it can take as long as 20 years for a gametophyte to send up a sporophyte, and when that occurs, it is usually a single spore-dusted stalkwhich sprouts a single leaf or frond, if any. There are two families within this phylum, Ophioglossaceae, and the moonworts and grape-ferns, Botrychiaceae. However, it should be noted that some biologists place moonworts with Ophioglossacea rather than Botrychiaceae. Adderstongue have more chromosomes than any other known plant. Gymnosperms (pines, conifers, and allies) are the third category of plants. As ferns and the allies before them, gymnosperms are vascular, but they have advanced an additional giant leap: gymnosperms have pollen, and produce seeds. Pollen allows fertilization to take place at great distance, via the wind, rather than directly running water. Seeds are the resultant embryos, but in an egg-like structure, rather than unprotected or nourished. Seeds store food for the embryo, and surround it with a hard case. This enables offspring to remain dormant until conditions are right, surviving off nutrients within the seeduntil, for example, the next rain. This greatly improves offspring survival rate. The name “gymnosperm” means “naked seed” referring to the fact that they do not case their ova in ovaries, but instead merely house their ova in cones. Concurrently, their pollen is not displayed in flowers, but simply thrown to the winds (it is because of this that pine pollen turns all Georgia yellow each spring.) To further legitimize the naked metaphor, the fertilized embryos (seeds) of gymnosperms are not set in fruits, but also thrown to the winds. Gymnosperms have four existent phyla, Pinophyta, Cycadophyta, Ginkgophyta, and Gnetophyta. Cycadophyta is the name of the cycad phylum. Though now rare, this was once a dominant phylum during the Jurassic. For this reason cycads are thought of as living fossils. They are evergreen and similar in looks to a palm tree, although true palms are angiosperms. However, the two groups share distribution somewhat, as cycads live in a wide range of equatorial environments, cycads having been found in sand, dirt and on rocks, in semi-arid and tropical regions about the equator. This is made possible by the small phylum being well adapted to heat and sunlight, as well as partially adapted to dry conditions, the partial adaption giving
• 6.
  flexibility. All cycadshave a symbiotic relationship with cyanobacteria, blue - green algae which lives with the cycads roots, nitrogen fixes the soil, and imparts a toxic quality to cycad seeds. Cycads, like ginkgoes, are either male or female, but never both. Cycad fossils have been found that are 280 megayears old, and there are possible (but disputed) cycad fossils dated as far back as 320 megayears ago. The ginkgo phylum has only one living species left in it, Ginkgo biloba. Fossils of this species, or one very like it, can be found as early as the Jurassic, making this tree one of the most well known examples of living fossils today. Ginkgo trees are either male or female, but never both, as many angiosperms are. They grow aerial roots very slowly some taking as long as 100 years, to no known purpose. Pinophyta(until recently, Coniferophyta) is the largest phylum of gymnosperms. So much so that it used to be considered the only phylum of gymnosperms.They were very successful at this, it appears, for while there are few species of conifers, they can be found on most of the world (see map below). As for the classification within Pinophyta, it is currently in dispute. Pinopsidia is the only complete class. The other classes are cited as no longer existent, or as merely divisions. Pinopsidiahas simple leaves and secondary root and stem growth. This class includes pines, firs, spruces, redwoods, yews, ect. As those familiar with plants can ascertain from the examples given, they cover a wide range, and are most important in boreal forrests of the north. Conifer’s distribution The phylum Gnetophyta is the most advanced of the gymnosperms. It is significant because, unlike other gymnosperms, it has an angiosperm’s woody vascular bundles. For this reason, biologists suspect it may be the “missing link” between gymnosperms and flowering plants. This phylum has three orders in it Gnetales, Welwitschiales, and Ephedrales. All together there are only six species in the phylum Gnetophyta.
• 7.
  Magnoliophyta (once calledAnthophyta) is the flowering plants. This is the only phylum of angiosperms, which means “enclosed fruit”. The flowering plants are the largest plant phylum in terms of number of species by a great deal. Angiosperms encase their seeds in fruit, and their ova are housed in ovaries, thus this phylum is protecting their offspring wherever possible. Fruits often store sugars in order to attract animals into eating them. After a fruit is eaten, the seeds (evolutionarily packaged to be indigestible) will pass through the digestive system of the animal and be deposited elsewhere with a pile of handy fertilizer. This process increases the rate of reproductive spread and success. Flowers are specialized leaves which all angiosperms have, whether they are as conspicuous as a venus flytrap or as easy to overlook as the flowers of an oak. Flowers often have sugary nectar for the purpose of attracting insects. These insects, while eating the nectar, will get pollen (male plant gametes) all over itself and then move on to drink from another flower, which will receive the pollen of the old, plus dust the insect with its own. This process is called entimophylly (pollination via insects). Most angiosperms are both male and female. Many plants like this can pollinate with themselves. Because of adaptations such as these, Angiosperms generally grow faster and reproduce surer than most conifers, leading to them taking over most forests in their “old growth” stage, as the final wave of assault by plants on rocks. They will remain that way until a new phylum of plants evolves. There are two classes within this phylum, monocot and dicot. Monocot’s seeds have one seed leaf, parallel veins, and tend towards fibrous roots. The number of floral parts is often a multiple of three. The vascular bundles are distributed throught the stem. Dicot’s seeds have two seed leaves, branched veins, and tap roots. Their floral parts are often multiples of four or five and their vascular bundles are arranged in a ring about the stem. Although it is not a rule, monocots are more closely associated with grasses while dicots are more often trees