The results of mitotic divisions include the two cells with the same chromosome as the parent cell. Further, the growth and development of zygotes from embryo to adult plants are facilitated by mitosis. Back in centuries, different taxonomists aimed to classify organisms in groups taxonomy. They identified the differences ad characteristics and grouped them.
Similarly, the plants, constituting the largest Kingdom with a wide range of plants from lower to high ordered plants, were classified.
The kingdom Plantae was divided into two main subgroups known as vascular plants and non-vascular plants. The classification of plants or any other organism is a continuous process going on for centuries.
Thus, botanical nomenclature international rules constitute revisions for plant classification based on several factors such as gymnosperms Penhallow and others that do not show characteristics up to international standards.
However, the recently revised classification pattern of plants classification consists of the following divisions and sub-division:. Division Thallophta consists of those plants e. Moreover, these plants either have no or less differentiated vegetative organs multicellular or unicellular.
In Division Embryophyta , the reproduction mode in these plants is oogamy meaning a form of sexual reproduction in which female gamete is larger and often non-motile compared to male gametes. This reproduction mode is accompanied by the formation of an egg that develops into a zygote and then embryo to grown adult plant alternation of generations.
These plants have true leaves, stems, roots, and flowers vascular plants. Tracheophytes are vascular plants with stem, leaf, roots, and vascular bundles xylem and phloem. The sporophytes live an independent life and eventually reduces to obliteration.
They are divided into the following types:. The pteridophytes consist of around species of ferns and non-flowering plants. These plants are seedless plants and incapable of transferring the genetic material DNA to their offspring using fruits, seeds, and cones. However, these plants produce spores known as sporophylls. The leaves of pteridophytes contain spores on the underside. These spores can cover long distances due to a flexible structure that throws sporangia spores structure containing spores.
The stems are called rhizomes horizontal and standard roots with a vascular system for transporting water and food. The most diversified phylum is Angiosperms that contains , flowering vascular plant species. The plants included in phylum angiosperms are shrubs, bulbs, parasitic plants epiphytes , trees, herbs, and other plants living in freshwater and marine habitats. The popular and largest families of the respective phylum include the family of orchids Orchidaceae , legumes Fabaceae , and daisies Asteraceae.
Are flowering plants vascular? Apart from the presence of a vascular system in these plants, other characteristics shared by members of this group are as follows:. The phylum gymnosperms differ from other phyla of plants sure to the presence of tall, thick, and old plants living.
These plants are found and widely distributed throughout the world and are more abundant in Arctic and Temperate regions. These plants are hemlocks, firs, and pines with similar characteristics such as needle-like leaves and big wood stems. The seeds of these plants are naked, meaning that any flower or fruit does not enclose them. Instead, they possess cones, also called a strobilus , for reproduction purposes. These plants produce two types of cones to distinguish male and female cones with a difference of size—the female cones are larger than male cones.
The vascular plants have an ancient history of about million years ago. It can be stated that these plants probably developed from moss-like or bryophytes ancestors, but in their life cycle, there is a dominant phase of diploid sporophyte generation; as time passed, they develop into the most advanced plants, and nowadays we find them with a more developed vascular system in these plants.
Vascular plants evolved true roots that were well modified as compared to rhizoids. These roots absorb more water, salts, and minerals from the soil. These roots keep plants anchor and secure into the soil. So plants can grow larger without tumbling. The stems of Vascular plants are well developed and have vascular tissues and lignin. This lignin gives stiffness to the plant, and due to the latter stiffness, the plants can grow high above the ground to get more air and light, which will help in photosynthesis.
The vascular tissues in plants keep the water, and food supply continues in the plant body. Thus, the plants remain hydrated without getting dry out in the air. The leaves of vascular plants are also well developed, broader, and larger. These structures allow leaves to experience more sunlight and increased photosynthetic processes.
Due to a vascular system in plants and other adaptions, these vascular plants are better than mine vascular plants as they can grow tall and take the advantage of sunlight high up in the air. Moreover, the early vascular plants were the pioneers of photosynthesis into the air. Plants, either vascular or non-vascular, are a way to a better environment and important for different living organisms.
However, vascular plants are widely spread and provide several benefits to creatures, including birds, animals, and humans.
Seedless vascular plants are beneficial in the ecosystem in providing food resources to animals and humans. Vascular plants are more complex than ancestral nonvascular plants. All types of vascular plants are terrestrial land plants not found in freshwater or saltwater biomes. Vascular plants are also defined as eukaryotes , meaning they have a membrane-bound nucleus, which sets them apart from the prokaryotic bacteria and archaea. Vascular plants have photosynthetic pigments and cellulose to support cell walls.
Like all plants, they are place-bound; they cannot flee when hungry herbivores come along looking for a meal. For centuries, scholars have used plant taxonomy , or classification systems, to identify, define and group plants. Animals came next, and plants were relegated to lower links of the chain. In the 18th century, Swedish botanist Carl Linnaeus recognized that a universal method of classification was needed for scientific study of plants and animals in the natural world.
Linnaeus assigned each species a Latin binomial species and genus name. He also grouped living organisms by kingdoms and orders. Vascular and nonvascular plants represent two large subgroups within the plant kingdom. Complex plants and animals need a vascular system to live. For instance, the vascular system of the human body includes arteries, veins and capillaries involved in metabolism and respiration.
It took small primitive plants millions of years to develop vascular tissue and a vascular system. Because ancient plants did not have a vascular system, their range was limited. Plants slowly evolved vascular tissue, phloem and xylem. Vascular plants are more prevalent today than nonvascular plants because vascularity offers an evolutionary advantage. The first fossil record of vascular plants dates back to a sporophyte called Cooksonia that lived about million years ago during the Silurian Period.
Cooksonia had stems but no leaves or roots, although some species are believed to have developed vascular tissue for water transport. Primitive nonvascular plants called bryophytes adapted to being land plants in areas where there was sufficient moisture.
Plants such as liverworts and hornworts lack actual roots, leaves, stems, flowers or seeds. For instance, whisk ferns are not true ferns because they merely have a leafless, photosynthetic stem that branches into sporangia for reproduction. Seedless vascular plants such as club mosses and horsetails came next in the Devonian Period. Molecular data and fossil records show that seed-bearing gymnosperms such as pines, spruce and ginkgoes evolved millions of years before angiosperms like broad-leaf trees; the exact time span is debated.
Gymnosperms do not have flowers or bear fruit; seeds form on leaf surfaces or scales inside pine cones. By contrast, angiosperms have flowers and seeds enclosed in ovaries. Characteristic parts of vascular plants include roots, stems, leaves and vascular tissue xylem and phloem. These highly specialized parts play a critical role in plant survival.
The appearance of these structures in seed plants differs greatly by species and niche. Roots: These reach from the stem of the plant into the ground in search of water and nutrients.
Seed vascular plants, whether an apple tree or a Ponderosa pine, produce microspores, which are male pollen. In a gymnosperm--like the pine tree--the pollen is borne by wind away from the plant with the intent of germinating female seeds. In an angiosperm, male pollen can be produced within the same flower where the female seed is produced. A seed vascular plant produces female megaspores, or seeds, that the plant retains through maturity.
In a gymnosperm--meaning "naked seed"--the ripe female seed separates from the plant and, if germinated by wind-borne pollen, takes root and develops into a new plant. In an angiosperm--meaning "seed vessel"--the seed germinates while still on the plant and develops inside the plant's enclosed ovaries to fruition.
There are only about 1, living species of gymnosperms , whereas there are hundreds of thousands of living species of angiosperms. Living gymnosperms are typically classified in the divisions described in the Table below. Most modern gymnosperms are trees with woody trunks. The majority are conifers such as pine trees. The earliest seed plants probably evolved close to million years ago. They were similar to modern ginkgoes and reproduced with pollen and seeds in cones.
Early seed plants quickly came to dominate forests during the Mesozoic Era, or Age of the Dinosaurs, about to 65 million years ago. Some also evolved adaptations to cold. They had woody trunks and needle-like, evergreen leaves covered with a thick coating of waxy cuticle to reduce water loss. The person standing at the foot of this giant sequoia shows just how enormous the tree is. Some early seed plants also grew very large. Eventually, some gymnosperms started to evolve angiosperm-like traits.
For example, cycad ancestors were the first plants to use insects as pollinators. They also used birds and monkeys to disperse their brightly colored seeds. Of modern gymnosperms, Gnetae probably share the most recent common ancestor with angiosperms.
Among other similarities, Gnetae produce nectar , a sweet, sugary liquid that attracts insect pollinators.
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