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Pollination (self & cross)

Let's explore pollination, its types and agents. Created by Mahesh Shenoy.

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Video transcript

flowers use their beautiful petals and fragrance to attract insects why do they do that because the insects help them in pollination so in this video we're going to see what pollination is and what are the different types and how exactly do the insects help so let's start with what is pollination pollination is simply the act of transferring the pollen grains from the anther these are the anther the top part of the male male organs to the stigma stigma is the top part of the female organ so let me just show that here is the pollen grain sitting on the anther top part of the male here is the stigma top part of the female the act of transferring that pollen grains from the enter all the way to the region from the anther all the way to stigma that's basically what we call pollination that's what pollination is all about now based on whether the pollen grains are transferred within the same plants or their transfer between two different plants we can classify them into two kinds so the first one we'll call self pollination self pollination and the second one will be something called cross pollination let me just read that correctly alright cross pollination so let's start with the self pollination what exactly is this so the name suggests if the pollen grains are transferred within the same plant itself then we'll say it's self pollination so one way that can happen is if you have four pollen grains transferred in the same flower so from the enter to the stigma of the same flower this is self pollination but even if you have pollen grains transferred from this from the anther to the stigma of a different flower belonging to the same plant I'll call this number 2 this is also self-pollination why because still the pollen grains are being transferred within the same plant the pollination is still happening the plant is still pollinating itself that's the whole idea behind self pollination okay so these are examples of self pollination for the first one to happen though a flower needs to be bisexual meaning it has to have both the male and the female reproductive parts only then it can do this on the other hand if the flowers are unisexual then they can still self pollinate this way a male flower can transfer pollen grains to a female flower belonging to the same plant on the other hand what do you think is cross-pollination can you guess that now what do you think is cross-pollination well cross-pollination is transfer of pollen grains from one flower to a flower of a different plant or a different tree so for example if you have pulling rains from here going all the way to the stigma of a different flower all together meaning different flower belonging to a different tree all together then that is what we call cross pollination across two different plants of course same species obviously but two different plants altogether so I'll call this as number three this is in pink so this is cross pollination now you might say cool but how exactly does the pollination happen how do the flowers take the pollen grains and transfer it to the stigma they don't have any moving parts now do they well that's a great question so the polar pollination depends on certain agents let me just write it down depends on certain agents agents are basically things that help in pollination one of the most common agent would be vind so the pollen grains will get just get sprayed into the air and then the wind will be the one that carries it forward and because both the pollen grains and the stigma is very sticky and the pollen grain comes very close to that stigma it'll just stick to it and of course in some cases they are not sticky but they are very hairy even then the pollen grains will get entangled very nicely with this stigma and may get stuck to it and pollination happens so with wind self pollination can easily happen because they're very close to each other right the stamen the pollen grains and the stigma are very close to each other so with wind or water just like how wind helps in transferring pollen grains for land plants water will help in transferring the pollen grains in aquatic plants but what about cross-pollination now you see for cross-pollination to happen the pollen grains need to get transferred from one plant or from one tree to another now these trees are very far apart then the chances of cross-pollination reduces right so how do we effectively increase the chances of cross-pollination this is where the insects coming to the picture so another important agent for pollination especially cross pollination would be insects insects like bees butterflies moths and even birds but how exactly do the insects pollinate let me take an example of a bee over here let's say this bee is flying and it's a little hungry and it spots a flower the flower attracts the bees by using its beautiful petals it's order and also by using the nectar now what exactly is nectar you may be asking well nectar is this sugary stuff that the flowers produce near its base base of the flower which has a lot of sugar it has a lot of protein so perfect for these hungry bees so what these bees do they get attracted to that particular flower they sit on that particular flower and they start drinking that nectar and as they start drinking that nectar the pollen grains start sticking to the bees let me show you a couple of photos of that here on the top you can see a bee drinking nectar from the flower and as a result you can see it's resting its legs on one of the answers and supporting grains can easily stick to the bee in the second case you can see a lot of pollen grains sticking to this B this bee has been super busy so coming back to our story a lot of pollen grains can easily get stuck to this be so pollen grains gets stuck to that bee let me now get rid of this photo and then when the bee decides to move away it carries those pollen grains with it now the B goes on its way on his journey long journey maybe to its home and then it spots another similar flower with the similar fragrance and the similar order and then again it gets attracted to it and starts drinking the nectar from that and while doing that some of the pollen grains get transferred to the stigma and that's how cross-pollination can happen but it's important that the bees need to get attracted to the same species of the flower for example if this is the papaya flower it needs to transfer that Polling rains to another papaya flower and not maybe watermelon flower and it's for that reason usually certain bees are always attracted to certain kinds of flower that increases the chances of successful cross pollination okay be you're done your job go home these bees turn out to be a major contributor of pollination okay now of course the pollination has happened but that's not the end of the story it's actually the beginning of the story remember the sperms in that inside the pollen grains still need to travel all the way into the eggs which are found in the ovaries and that is something we'll talk about in the future video so what did we learn in this video we learned about what pollination is which is basically the transfer of pollen grains from the anther the top part of the meal to the stigma the top part of the female organ and this can happen in two ways self pollination is when the pollination happens within the plant this can happen within the flower or within two different flowers of the same plant and cross pollination is when pollination happens between two different plants so from one flower of one plant to a flower of a different plant all together and then we saw the agents are basically what what causes pollination the examples of that would be wind and water and certain insects also help in pollination