[Music] this video on pollination is part of a series on plant reproduction you'll need to have a basic understanding of the parts of a flower so feel free to go back over and watch the video on that if you need to links are in the description sexual reproduction in flowering plants requires male gametes produced in pollen grains in the anthis to fuse with female gametes found in the ovules a pollen grain must reach the stigma before its nucleus can travel down towards the female gamete in the ovule pollination the part we're covering in this video is this step here the movement of pollen from the anther to the stigma in case it's not obvious the definition for pollination is simply the transfer of pollen from the anther to the stigma it can occur from the anther of a flower to the stigma of the same flower or to a stigma of a different flower on the same plant or to the stigma of a flower on a different plant pollination involving the same plant is referred to as self-pollination regardless of which flowers are involved pollination involving two flowers of separate plants is called cross pollination note that these are different plants but of the same species we're going to look at two strategies the different plants have to make pollination happen we'll look at insect pollinated flowers and wind pollinated flowers we'll start with insect pollination flowers that rely on insects have several strategies to attract them they tend to have brightly coloured petals which are appealing to insects as well as a strong scent that they like many flowers also have nectaries which produce nectar a sugary substance that insects feed on notice that the nectary is located far below the anthers where the pollen is produced as an insect visits a flower to get its fill of nectar it can't avoid getting pollen from the anders trapped on its body the pollen grains produced by insect pollinated flowers tend to be sticky or spiky so it's really easy for them to cling to an insect's body obviously these insects aren't stopping at just one flower as they carry on visiting other flowers some of those pollen grains trapped on their body are bound to get deposited on the next flower some of these pollen grains will land on the stigma the stigma of this type of flower is a sticky structure ideally suited for pollen to attach to some insects are actually pollen eaters and they visit flowers to eat the pollen itself this might seem very unhelpful to flowers but it's just a simple trade-off while insects are feeding on the pollen they'll no doubt get some trapped on their body flowers can afford to sacrifice and pollen to insect consumption provided at least some of it is trapped and transferred on the body of that insect so insects gain a food source from flowers whether it's nectar or pollen or both while flowering plants gain an opportunity to reproduce thanks to the insects this sort of relationship where two organisms interact in a way that they both benefit is called mutualism it's not only insects that act as pollinators some birds feed on nectar and so as they go from flower to flower they transfer pollen as they go there are also many species of bat that feed on pollen or nectar and there are even examples of lizards and geckos that are pollinators we've looked at insect pollinated let's look at wind pollinated flowers if you haven't studied this before you probably didn't know that these were even really flowers you certainly wouldn't give them to someone on valentine's day they don't look pretty or smell nice because there's no benefit to having large colorful petals or producing a scent they don't need to attract an animal on these flowers you can see the stigmas here as well as the anthers the structures may be a little more clear on this simplified diagram of a wind-pollinated flower let's compare it to an insect pollinated flower insect pollinated flowers tend to have anthers enclosed within the petals encouraging insects and other animals to brush against them wind pollinated flowers have exposed anthers this allows wind to catch the pollen released from them compared to the larger sticky or spiky pollen grains of the insect pollinated flowers wind pollinated flowers produce smaller lightweight pollen grains allowing them to be carried easily in the wind and the pollen grains are usually produced in larger numbers to account for the fact that only a small fraction of the pollen that leaves the anther will find its way to a stigma of the same species of flower where the stigmas of insect pollinated flowers tend to be sticky to allow pollen on insects to attach the stigmas of wind-pollinated flowers are usually feather-like in structure this makes it easier to trap pollen passing by in the wind the next step for reproduction and flowering plants is for the male gamete to travel to the ovule where fertilization can take place that's all covered in the next video which is linked in the description [Music]