A World Without Plants: The Study of Angiosperms - Essay Sample

Introduction

Have you ever wondered about a world without plants? It is important to consider the study angiosperms as they play a critical role in our day to day activities and they are very important in ensuring our sustainability. Plant organisms originate from pre-existing cretaceous early floral species that involve angiosperms in their lifespan, especially during pollination. The evidence that proves that the pre-cretaceous were generated from megasporophylls is the fossil records. The Megasporophylls bears ovules that develop into fruits that contain the seeds. There is an evolutionary event that is responsible for the development of the basic genetic makeup of an angiosperm. This paper will be concerned with the innovation that has been observed in flowering p0lamnts throughout geological time. The paper is also going to focus on already available documented through the comparative morphology of plants.

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The Development of Separate but Close Proximity Between the Pollen and the Seed

The major evolutionary innovations by angiosperms is concerned with reproduction, evolution of flowers and fruits. The positioning of the seed organs and the pollen grains in a proximity ensures efficiency in fertilization. The closing of the flower carpel takes place in two stages, the loose closing and the complete closure stage. This gives rise to the origin of ornat5e that is radially symmetric flowers. The development of a bilaterally symmetrical flower and the development of fleshy fruits is a mechanism by the angiosperms to ensure its reproductive life.

The development of Medullosain Paleozoic seed plants is classified as seed fern. They generally produce both seeds and pollen-bearing organs on their leaves. The pollen organs of this type are not positioned near the seed-bearing organs however, they are adapted in a way6 that they are borne on a separate leaf and some are even developed in separate plants (Alboresi et al p106).

The prepollen medusa is known as the monolates has a large size in length and it indicates that the insect carries it from the pollen organ to the micropyle of the ovule which happens to be close to the pollen-bearing organs of seed ferns. They are always found separate from each other and it is evident that they developed from different leaves or might have developed from separate plants. It is evident also that pollination might have been executed by insects or by the wind.

There is also evidence that some Mesozoic plants were associated with insects. These plants include Bennettitales and seed ferns. The majority of such plants exhibited separate ovule bearing and pollen, however, the pollen organs were separated from ovule bearing organs. The pollen organs were positioned near the ovules. It was evident in Williamsoniella and cycandeoidea. Both these genera, the pollen organs are involved to exact axis that finishes the seed-bearing vessels. These pollen structures appear to have been advanced from pollen-bearing leaves where prepared in spirals and subtended the seed-bearing receptacle. The angiosperms follow this arrangement.

The bennettitaleans might have not followed these arrangements that the angiosperms evolve through, they give a strong indication of co-evolutionary influence that insects played as co pollinators played in mid-Mesozoic plant replica. The process of insects visiting the propagative organs of the bennettitaleans displays that the capability to bring the pollen-bearing and ovule bearing organs together seem in another group of seed plants that is fully independent of the angiosperms. Seed ferns also experienced the biotic pressures, it is evident that the angiosperms are likely to have evolved from this line. The idea is informed by the fact that the organization of the paleobotany.

When angiosperms are concerned, seed-bearing leaves are reflected as plant parts that are necessary for the origin of the seed manner carpels. Seed-bearing carpels are allowed critically on one of the earliest known examples of complete propagative blossoming plans alignment Archaefructus In Archaefructus the parts that bear pollen are situated below the carpels which makes the ovule bearing and the pollen-bearing are brought close to one another. This feature was responsible for making it possible for visiting insects to pick pollen from adjacent stamens and deposit pollen on the carpels that contain the immature ovules. The features also favor's wind pollination. This takes place when adjacent angiosperms are able to produce sufficient quantities of the pollen (Coen et al p 2510).

It is evident also that the Archaefructus spreads its generative sprouts above the water surface that is opposing to the flooded flowering. By presenting the ovule bearing and pollen modus structures close together appears to have remained seem of the first angiosperms. It is a characteristic of ancient angiosperms. It gives the history of flowering plants.

The Closure of Carpel in Two Stages

The closed carpel is a prominent feature of the angiosperms. This characteristic is utilized to define the ancient angiosperms in the fossil records. The characteristics that utilize the pollen, wood, and leaves that is informative cannot unequivocally to article the arrival of ancient angiosperms. Although the ancient records of angiosperms and pollens that resemble them traces back to ancient angiosperms as it gives an interesting and important data that gives a character that resembles the angiosperms according to the early fossil record. The Geochemical data proposes that a pre-Mesozoic angiosperm ancestry. A closed carpel can be traced back to about 125 million years (Reyes, et al 950).

It can be hypothesized that the earliest carpels of flowering plants did not have firmly locked carpels and their in-between ancestors. When the female and male come to close nearness and became combined in a single shoot, this led to angiosperms develop in turn closed carpels. The Paleozoic seed ferns produced clear leaf borne seeds that had microphyles which in turn produced pollination droplets. The ovules of these angiosperms were abided alongside the leaf edge and others bent their leaf margins inside and their microphyles pointed inwardly.

The partial closure of the carpel is projected to have been an innovation that came to place when the angiosperms were developing mechanisms to prevent self-pollination. The coming closer to the ovule producing and pollen organs. However, there is no fossil evidence that indicates the early occurrence of the self-incompatibility in the angiosperms. The evidence of the proximity of the ovule and pollen organs indicates the existence of self-incompatibility that existed millions of years ago.

The closure of the carpel is continued probably to follow the nature of the pollination fluid in an open carpel. This cross-fertilization by the fluid is significant in ensuring outcrossing which could be washed by water. The water dilutes the pollen compromises the space of the pollination fluid nature. The reproductive organs of the aquatic plant are held above the water surface to ensure the floral part is in open riparian environment to heavy dew, rain and in some cases flooding. Carpel usually closes to ensure there is protection of the response to external interaction such as insect allogamy.

The young ovules are located inside the carpel wall having the seed inside at the early angiosperm evolution. The flower being rich in nutrient content attracts flies when partially closed. The closed carpel ensures the protection of the Angiosperm from external small creatures that may be beneficial or destructive to the plant's reproductive organ. The genotype of the carpel is of significant value to the active sites of the pollen for the pollen grain to grow and male genotype collaboration and incapability (Sokoloff, et al p 101).

The significance of the carpel is recognized when it closes the hot point delicate part of the flower during the reproductive event of the flower. The carpels are surrounded by the ovules systematized with their interlinking and secretions to ensure that t is total closure of the flower. The lower part of the angiosperm is familiarized by the systematic arrangement of the protective mechanism among all types of the angiosperm. The sepal and carpel including the pericarp part of the young fruit play this essential protection role in angiosperm evolution reproduction.

The biology of the genotypes of the terrestrial plant together with the angiosperm plays a major role in the fruition of reproduction. The potential plant during the evolution of the land plants are free dispersed by the spores that reproduce the motile sperm cell. The seed development rises from fertilization of motile sperm cells in the proximately of the micropyle. This is the route where the pollen begins its cell division immediately on entry to the ovary by the semen. Pollinators facilitate the process through colonization bay the scent, color attraction, and nutrient attraction to aid in the process of autogamy. The land seed-bearing plant today have pollen tubes which deliver non-motile sperm nuclei which had evolved and found intergraded most seed-bearing plant.

Origin of the Polysymmetric Flower

The oldest generative flowering plant known as Archaefructus has no clear evidence of the access organs such as petals or sepals. The flower consists of so many singular terminal carpels that approximately suspended by numerous specific shoot bearing.The most potent evolutionary relationship between flowers developing good features to improves on its adaptation against the flower predators. The characteristics lead to a diverse species observer by the earlier scientist in research. This led to the observed gradual change of the flower leading the different classification of flowers (Soltis et al p116).

The angiosperm produced flowers in the same Pattern indicates that all flowers having the ovules compacted together in consideration to the monophyletic group showed by the closed flowers.The combination of the stamens and carpels on the same axis may have followed a single path of progression.The stamen of the flower being the basic sexual part of the flower followed evolution. This in association with the stamens with carpels in various ways which reduce the modification and get lost over a certain period. These continued changes in the flower of losing and getting some new adaptive features confirm the progression progenitor. Multiple origins of the flower emerged from the radiation of the angiosperm from the earliest times onwards.

Plant flowers have shared lineage from their features notwithstanding their different evolution of the leave arrangement. They have the same simple structures which are modified during the growth and development from the root and shoot apex. The common lineage they share as they segregated in numerous surroundings. The genetic relationship between the angiosperm from their ancestry which may be sexual or asexual reproduction. The organization of the propagative structures such as the shoot apex may have been coined from the various lines of radiations.

The homology of the reproductive tissues within the flowering plant is evidently specified to multiply in distinguished set in what has been named as the petal and sepal evolution. Some of the familial states may have unisexual therefore may have lineage released. Fossil records show that the flowering plants had bisexual today unlike in the olden days.This shows the stable deviations from the pre-existing shoot, some leaves are fertile with terminal bearing of the ovules.Pollen organs entice pollinators by manufacturing a nectar in the petals which are suspended to be combined to leaves backing up the floral part (Thornhill et al p 2095).

Adjustment of the shoot dec...