BIO 210- 01
Plant sexuality has a wide range of topics about sexual reproduction systems found across the plant kingdom. Flowers, which are the reproductive units of angiosperms, amongst all living things are physically varied the most. They also show the greatest diversity in methods of reproduction of all biological systems. The system for classifying flowering plants was proposed by Carolus Linnaeus, which is based on plant structures. Plants employ several different morphological adaptations that involve sexual reproduction. Christian Konrad Sprengel studied plant sexuality, which brought understanding to the pollination process. This process involved both biotic and abiotic interactions. Charles Darwin’s theories of natural selection utilized Sprengel’s work to promote his idea of evolution. Sprengel called his discovery the “revealed secret of nature.” Non- flowering plants such as green algae, mosses, liverworts, hornworts, ferns, and gymnosperms have complex mutual reactions between morphological adaptation and environmental factors in their sexual reproduction. The process of how the sperm from one plant fertilizes the ovum of another, the breeding system, is the single most important factor of the mating structure of plant populations. The amount of distribution of genetic variation is controlled by the mating structure of the flower parts and their arrangement on the plant.
There are many different parts of the flower. The male parts of the flowers consist of three parts: stamen, anther, and filament. The stamen is made up of the filament and anther. The anther is the pollen producing part of the plant. The anther sits on top of the filament. The female parts of the flowers consist of five parts: pistil, stigma, style, ovary, and ovule. The pistil is made up of the stigma, style, and ovary. The stigma is the sticky bulb in the center of the flower that receives the pollen grains and on which they germinate. The stigma sits on top of the long stalk of the flower that is called the style. The ovary is located at the bottom of the flower that has seeds inside and turns into the fruit we eat. The ovule is the part of the ovary that becomes the seeds. Other important parts of the flower are the petal and sepal. The petals of the flower are colorful, and attract pollinators. The sepal are the parts that look like green leaves that covers the outside of a flower bud in order to protect the flower before it opens.
Figure : Basic parts of the flower
One or more ovules and the female gamete develop inside the ovary. Ovules begin life as a small projection into the cavity of the ovary. Still remaining attached to the ovary wall by a placenta, the ovule bends as it grow and develop. In the beginning, the ovule is a group of similar cells that is called the nucellus. The nucellus contains the embryo sac. As development continues, the mass of cells differentiates to form the inner and outer integument that surrounds and protects the nucellus, but leaves a small opening called the micropyle. This opening is to allow male gametes to pass and interact with the female gamete (haploid egg cell) located in the embryo sac. Each anther contains four pollen sacs. Pollen grains develop inside each pollen sac that begins with a mass of large pollen mother cells in each sac that are all diploid. The wall thickens in each pollen grain and forms an inner layer called the intine and an outer layer called the exine. Surface patterns are different on pollen grains from different species. After pollen grains have matured, the anther dries out and splits open, which releases the pollen. This process is called dehiscence.
Cross- pollination is favored amongst many plants. Therefore, pollen must be transferred to the stigma of another in order for sexual reproduction to take place. Some flowers rely on the wind and some the insects to...
Cited: All Family Resources - a guide to resources services for families. FLOWER ANATOMY parts of a flower. Retrieved April 11, 2014, from http://www.familymanagement.com/holidays/flowers/flower_anatomy.html
GCSE revision and A level revision | S-cool, the revision website. A-level Biology Reproduction Revision - Sexual Reproduction in Flowering Plants | S-cool, the revision website. Retrieved April 11, 2014, from http://www.s-cool.co.uk/a-level/biology/reproduction/revise-it/sexual-reproduction-in-flowering-plants
Official Website Home Page | List of Biology Topics. Introduction to Plant Sexuality. Retrieved April 11, 2014, from http://www.biology-nation.com/Introduction_to_Plant_Sexuality.html
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