As I saw from my childhood while doing prayer we use banana/coconut as one of the puja ingredients.
Why do we use these particular fruits rather than others? Why do we give special importance to them?
I think it is not important which fruits you uses by the pooja. But it is important that all fruits are fresh, clean and satvic from the art.
The bananas and the coconuts are cheap in India and because of this they are most used for the pooja.
Besides of this fresh green coconuts are very satvic because the water inside them is very clean.
The coconuts and the bananas are the food from ascetic and because of this are symbolically represents ascetic god Shiva.
Warning about following content
As soon as I have seen, that so many people are interested to know the answer of this question, I have understood that I have to do more researche behind this question. I have found a lot of different meanings and opinions...
But I have to warn you before you read it: this all citats comes not from holy scriptings! Be careful when you use it. Only one reason why I add all this here is that the wish to understand it is big and unfortunately we don't have this answer in our holy scriptings. The recommendations can not give us the answer to the question "Why?".
May be this does not realy belong to Hinduism, but it is used in Hinduism and we want and have to find the answer...
Different meanings and opinions which I found on the links below:
Coconut and Banana are the only two fruits which are considered to be the "Sacred fruits". All other fruits are tainted fruits ( partially eaten fruits), meaning other fruits have seeds and which have the capacity to reproduce!
But in the case of coconut, if you eat coconut and throw its outer shell, nothing will grow out of it. If you want to grow a coconut tree, you have to sow the entire coconut itself. Similarly Banana. If you eat a banana and throw its out sleeves, nothing will grow out of it. Banana tree is grown on its own when a banana plant start giving fruits.
The outer shell of coconut is the Ahamkara or ego, which one has to break. Once the ego is shed the mind will be as pure as the white tender coconut inside. The Bhavaavesha or Bhakthi will pour like the sweet water in it. The 3 eyes on the top they explain as Satwa, Raja and Tama or Past , Present and Future or Sthoola, Sukshma and Karana Sareera or body etc.
In Tamil nadu, coconut tree is called as thennam pillai meaning coconut child and they never call it as a tree but only as child. Even cutting of a live coconut tree is considered a sin and equivalent to that of murdering their own child in Tamil culture.
A coconut tree may consume any type of water from sweet ground water to salty sea water but the fruit which it bears always gives only sweet water. This is equivalent to that of life of an ascetic or a mother because only they give good things to their followers and children. For this reason, pregnant ladies are not allowed to break open a coconut as it is equivalent to kill a life form and moreover the vibrations from breaking a coconut could harm the fetus in the womb.
A coconut resembles the head of a human - Hard shell is covered by unwanted hair like coir, eyes are covered by a hard and sharp coir imitating our pride, hard shell denotes the egoistic selfishness, sweet water denotes the humane nature and the white sweet layer denotes the pure soul. One breaks open the coconut during pooja to indicate that ego, selfishness and pride to expose the soul to the God.
Coconut has three eyes and is symbolically represents Lord Shiva. This is the reason why in any rituals coconut is made a witness to indicate that it happens in the presence of Shiva. Coconut has neither a beginning nor an end and it indicates the Shiva form.
According to a legend, Vishwamitra was moved on seeing the animal sacrifice or human sacrifice in Hindu rituals. In order to end such life sacrifices, Vishwamitra introduced breaking open a coconut which resembles a life form. From then coconut breaking is included in all Hindu rituals.
Coconut is called "Shri-Phal" in many scriptures. Along with coconut the bananas are also called Shri-phal. "Shri" means Laxmi/Goddess of Wealth. So Shri-Phal means the fruit of Laxmi.
The reason is that these fruits are easily available. They are abundant and they are available in all the seasons. Any house which has a few coconut and banana trees in their garden, the family of that house will never starve. They will have ample supply of food through thick and thin. Thus these fruits are worshiped and are considered the gift of Goddess Laxmi. These fruits are hence used all religious ceremonies as a mark of prosperity and gratefulness to the Gods.
Coconut can be symbolised as human ego. Breaking it in front of God shows you are breaking your ego. It is like offering yourself to God. That's what I have listened from movies and people.
Our rishis and munis studies different plants and trees, and various other aspects of nature in depth. They found that the coconut was the most auspicious fruit, as it has the potency to draw divine vibrations from the outer world. For this reason, it is also known as shriphal or ‘divine fruit’. When the coconut is broken by smashing it on the ground, one can hear a sound similar to that of the monosyllabic mantra, ‘phut’, which can ward off the ill effects of an evil eye.
The coconut is one of the most common offerings in a temple. The shape of this fruit is akin to a human head with three eyes. When it is to be offered to a deity as this is the sensitive side of the fruit that can receive divine vibes from the idol. According to legend, the coconut was created by the rishi Vishwamitra for the well-being of humanity. When we offer a coconut at the feet of a deity, we symbolically offer our head, implying total surrender to the Divine by detaching our ego from the self.
Coconut water, like Gangajal, is deemed sacred. It is sprinkled to remove the negativity of an kernel of a broken coconut is later distributed to devotees as prasad. Coconut is also offered while undertaking or dam, on buying a new vehicle, on entering a new house, during weddings, celebrating festivals, and also so on. On concluding a haven, the purna ahuti or final offering is made by offering a ripe coconut into the sacrificial fire.
Breaking a coconut is the symbol of ones intention to sacrifice ones Ego in the presence of God, for whom all creatures are the same. It is expected that the person offering the coconut would be cognizant of this and would try and be a better person.
With the introduction of railways it became very easy and cheap to transport coconuts to all parts of India, hence their easy availability made them more popular for this ritual.
In India Coconut is used during various auspicious occasions, it is tied as torana at the door of homes during all auspicious functions, it is given to a bride before she leaves for her in law’s place, it is also gifted to people when they visit one another. Coconut is very auspicious and the symbol of fertility. Hence it is said that a lady who wishes to get a child should plant a coconut tree or offer coconuts to gods or goddesses.
Coconut water is untouched by hand and pure since it gets formed and preserved inside the shell. Its purity is considered equal to that of Gangajal (water from river Ganga).
The coconut has three "eyes" representing Shiva. The two eyes are on the same level while the third one is above, hence symbolizing turiya or the fourth state of supreme consciousness. So, the fruit depicts samadhi, or yogic perfection.
The coconut is dark and hard. It represents perfection of character, just like that of Krishna. A dark color is free of spot, you cannot create a mark on black. It is only white that gets dirty. Likewise, that which is hard cannot be broken by outside impact. It has integrity and perseverance. Being hard and dark on the outside, it symbolizes the outer characters of a religious man, firm, steadfast, undeviating, and not perturbed by turmoils. Since the man is rooted in “dharma” or righteousness, such a man cannot do “adharma” or immoral acts. Even the greatest act of immorality done by that man cannot add a blemish. Like Krishna (the dark color) he is free of spots. Whatever such a person does cannot be immoral even if the act is heinous.
On the inside, the coconut is white and tender. When protected, there is nothing as pure as white. Impurities are hidden in black, but they do not even exit in white in the first place. White is so pure that even the slightest hint of impurity is seen on it. It shines distinguished from all that is impure. It represents inner perfection, like that of Shiva. Shiva is known as Bholenath or the innocent lord. He is so pure and simple that he never tries to harm even the oppressors. He is so untouched that the slightest hint of imperfection around him gets noticed. Nobody can stand in front of him and appear as pure, his purity would immediately reveal the impurity of others. The inside is tender representing the compassion and benevolence of Shiva.
The hard outside and the soft inside represents the combination of practical and spiritual perfection. A soft heart must have a hard sword or it would get crushed. A tender smile must have a strong character, or it would be wiped off. To be the epitome of compassion & justice, one needs to be the epitome of strength & valor; or else who would implement the justice in the absence of strength?
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Because the scriptures recommend these fruits to be offered to deities.
From the chapter of the Devi Bhagvatam (DB) that describes how to perform the Navaratri festival we get the recommended list of food offerings to Devi as follows:
28-31. First of all, one should worship duly the Goddess Jagaddhâtri, presenting Her Chandan (sandal paste), Aguru (a fragrant wood, the aloe wood), Camphor, the flowers Mandâra (one of the five trees of the celestial regions), Karaja a kind of fragrant flower)! As’oka, Champaka, Karavir, Mâlatî, and Brâhmî and various lovely sweet scented flowers and good Bel leaves, Dhûpa (incense, a fragrant gum burnt before idols) and lamps. Next one should present the fruits coconut, Mâtulinga, the pomegranate, bananas, oranges, the jack fruits, Bel and various other delicious fruit and then, offering Her arghya, present boiled rice and other food with a heart, full of devotion.
Similarly, in another chapter of the same Purana, we find what the recommended food offerings are in general for any deities.
. O Good One! Now I am speaking, according to my knowledge, about the offerings as ordained in the Vedas or Tantras. Hear. Fresh butter, curd, thickened milk, rice freed from the husk by frying, sweetmeats (Til Laddu) prepared of Til, sugar cane, sugarcane juice, nice Gud (molasses), honey, svastik, sugar, rice (not broken) out of white Dhân, chipitak of table rice (Âlo châl), white Modak, Harbisyânna prepared of boiled rice with clarified butter and salt, Pistaka of jaoâ or wheaten flour, Paramânna with ghee, nectar like sweetmeats, coconut, coconut water, Svastik Pistaka, Svastik and ripe plantain Pistaka, Kaseru (root), Mûlâ, ginger, ripe plantains, excellent Bel fruit, the jujube fruit, and other appropriate white purified fruits of the season and peculiar to the place are to be offered in the Poojâ. (DB 9.4)
Similarly, yet another passage of the Purana mentions the kind of offerings that please the Mother Goddess.
The World Mother becomes very much pleased when one offers to Her the following things :-- Gur, honey, ghee, milk, curd, Takra, apûpa, fresh butter, Karkatî, Kusmânda, Modaka, Panasa, plantain, Jambu (rose-apple), mangoe, sesamum, oranges, Dâdima, (pomegranate) Vadarî (Jujube) the Dhâtrî (Âmalaki) fruit, Pâyasa, Prithuka, gram, coconut, Jambîra. Kaseru, and S’ûrana. The auspicious events occur when these are offered (DB 8.24)
So, fruits like coconut, banana, Bel fruit, Amalaki etc are auspicious to be offered in Pujas.
As the last line says auspicious things happen when those are offered.
And, besides that, coconut is quite an indispensable article to have in a Puja. Because in all Pujas we first install the Kalasha filled with water and on top it a coconut is to be placed covering the water filled Kalasha.