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There is absolutely no doubt that one of the most important characteristics of any living organism is the reproduction, that is the ability to produce new organisms. Without the ability to procreate, life would have ceased existing. Depending on the organism, there are different modes of reproduction, ranging from sexual to asexual. 

Sexual reproduction involves the use of sex organs and gametes while asexual reproduction involves nothing but only vegetative parts such as budding, fragmentation etc. Sexual dimorphism usually occurs in sexually reproducing organisms, that is they exist as males or females while some combine the attributes of both sexes - hermaphrodites. Both sexual and asexual reproduction are exhibited by plants and animals, although the majority of animals are sexually reproducing.

No one can spell sexual reproduction without the word 'sex'. This is because most often, the process involves the meeting of male and female organs (coitus) and eventual meeting and fusion of the male and female gametes to form the zygote. This is what is usually obtained in most animals. The motile sperm which is the male gamete is released from the male organ during coitus. Afterward, it swims to and fuses with the stationary female egg or the female gamete in a fertilization process.

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When it comes to plants, the story is a bit different. Even though sexual reproduction does occur in plants, it does not involve sex albeit there are males and females sexual organs. Rather, the male gamete of the plant uses various means to get to the female gametes in order for fertilization to take place. The males always have to do the job, isn't it? :).

Angiosperms are commonly referred to as flowering plants and they represent the most evolutionarily advanced group of plants in nature. As a form of reminder, the plant kingdom consits of algae, bryophytes, ferns, gymnosperms and angiosperms in order of both evolutionary and complexity advancement.

The organs for reproduction in angiosperms are within a structure known as flower, an equivalence of penis and vagina in humans. While the male organ is called the androecium, the female organ is referred to as gynoecium. The androecium is made up of a number of stamens each consisting of anther carried on a thin stalk known as filament. The gynoecium consists of the carpel which is made up of stigma, style and the ovary which houses the ovule. A flower carrying both the androecium and gynoecium is said to be bisexual/perfect or hermaphroditic flower. A flower that contains either of male or female reproductive organ is said to be unisexual/imperfect or incomplete flower. 


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In some species, male and female flowers are borne on separate plants, such plant species are said to be dioecious. The male plant produces male flowers which produce pollens without seeds while the female plant produces the female flowers which produce the anther and ends up forming seedless fruits. However, some plant species have both the male and female flowers on a single plant, such plant species are said to be monoecious. Another variation is such that some plant species produce bisexual or hermaphroditic flowers, consequently, they are said to be hermaphroditic plants. 

Even though there are males and females sex organs in flowering plants, fertilization usually takes place without coitus. The haploid male gamete also is known as pollen is produced by the anther through meiotic division. Nature has a way of indirectly making the pollen to find its way down to the ovule through a process known as pollination. In this process, matured pollen is dispersed either by wind or insects towards the ripened stigma which usually has a sticky surface. After landing on the stigma's surface, the pollen germinates and the resulting structure known as pollen tube grows through the style of the stigma and reaches the ovule.

<div class="pull-left">https://upload.wikimedia.org/wikipedia/commons/thumb/2/2d/Embryosac-en.svg/300px-Embryosac-en.svg.png <center><sup>By Lokal_Profil, <a href="https://creativecommons.org/licenses/by-sa/2.5" title="Creative Commons Attribution-Share Alike 2.5">CC BY-SA 2.5</a>, <a href="https://commons.wikimedia.org/w/index.php?curid=4189461">Link</a></sup></center></div>

Structures known as embryo sacs are present within the ovules. These structures represent highly reduced female gametophytes. Within each embryo-sac are three-celled egg apparatus which include a single egg cell, two synergids, three antipodal cells and two polar nuclei. The polar nuclei eventually fuse during the process of fertilization to produce a diploid secondary nucleus. 

Like I said earlier, the pollen grain germinates on the stigma and the resulting pollen tube grows through the tissues of stigma and style and enters the ovule from the micropylar end. Upon successful entry of the embryo-sac, the pollen tube discharges two sperm cells out of which one fuses with the egg cell to form a zygote and the other fuses with the diploid secondary nucleus to produce a structure known as the triploid primary endosperm nucleus. Consequently, fertilization in flowering plants is generally referred to as double fertilization.

Do you ever wonder what happens to some of the flower structures after fertilization? As a rule of nature, the fertilized ovule becomes what is known as the seed while the ovary which houses the ovule becomes the fruit. Some ovaries houses more than one ovlue, hence, fruits that develop from such ovaries usually have more than one seeds. Other flower structures such as the petals and the sepals dry and fall off. 

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### Summary
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Sexual reproduction in sexually reproducing organisms always requires the participation of male and haploid female gametes usually derived from male and female reproductive organs through meiosis. The two haploid gametes fuse to form a 2N zygote during fertilization. In most animals, the process is usually preceeded by coitus. However, in angiosperms (flowering plants), the process is preceeded by pollination. 

The reproductive organ in the angiosperms is the flower. Some flowers can have both male and female reproductive parts while some will only have either of the two at a time. Male/female unisexual flowers can either be on the same plant or on different plants; a condition known as monoecy or dioecy respectively.

The anther of the male flower organ releases pollen grain which is either carried by wind or insect to the stigma of the female flower's organ. Thereafter, it germinates and the resulting pollen tube penetrates the ovule and release its contents which then fuse with the contents of the ovule to complete the fertilization.

So much for angiosperm's sex.

Thank you for reading.

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### References
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[plant fertilization](https://biology.tutorvista.com/plant-kingdom/plant-fertilization.html)

[flowering plant sexuality](https://simple.wikipedia.org/wiki/Flowering_plant_sexuality)

_All images with uncited sources were taken using Samsung S4 and edited using paint_

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