 When you look at flowers in trees, have you wondered if there's any pattern in how the flowers are arranged? Take a look at these flowers. We have begonia, mustard, orchid and this funny looking flower over here is called bladder campion. Do you see any similarities or differences in how the flowers are arranged in these plants? Take a minute, pause the video if you want and note down your thoughts. So let's understand the pattern of floral arrangement. First off, what is a flower? A flower is the structure in angiosperms that houses the reproductive structures of the plant. It is formed when the shoot apical meristem becomes the floral meristem. The arrangement of flowers on the floral axis is called inflorescence. Now what is a floral axis, you may ask? The floral axis is the part of the flower on which the reproductive structures and the other ancillary parts of the flower are attached. So there are two main types of inflorescence. Rasmus and cymos. Let's delve deeper into each type of inflorescence. In Rasmus inflorescence the main axis of the stem keeps growing and the flowers are formed laterally to the sides. So here in this plant the stem would have initially been say this high as the plant was young and when it was this high this flower formed to the sides laterally and then when the stem continued to grow newer flowers will be added to the top of the older flower. So in Rasmus inflorescence the main axis continues to grow and newer flowers are added on top of the older existing flowers. So this pattern of arrangement where newer flowers are on top of older flowers is called acropetal arrangement and this is commonly seen in leaf formation as well. When leaves are formed they follow the acropetal arrangement as well. So because the main axis continues to grow in Rasmus inflorescence it can still continue to grow and produce more flowers to the sides. Rasmus inflorescence is also called indefinite type of inflorescence. So examples of flowers that display Rasmus inflorescence include Gulmohar. Here you can see this is the main axis that can continue to grow and the flowers are added to the sides laterally. So this here this water most flower is the older flower and newer flowers are added to the sides as the main axis keeps growing. Other examples include mustard, radish and orchid and we saw mustard and orchid flowers earlier in the video didn't we? Those flowers also display Rasmus type of inflorescence. In Symos inflorescence the main axis first terminates in a flower. Unlike in Rasmus inflorescence where the main axis continues to grow in Symos it terminates in a flower and this is the first flower that is formed in this axis. After this flower has formed which is now the older flower newer flowers are added below the older flower in this arrangement. So this type of arrangement where older flower is on top and newer flowers are added below the older flower is called Basipete. So because in Symos inflorescence the main axis terminates in a flower it cannot grow indefinitely like in Rasmus inflorescence right? That's why Symos inflorescence is also called definite type of inflorescence. Examples of Symos inflorescence include Callotropus which is here this is the older flower the main axis has terminated below this newer flowers are beginning to grow. Other examples include Begonia, Boganvia and Jasmine and even the bladder campaign example that we saw earlier in the video that also displays this Symos type of inflorescence. So the next time you see a flowering plant try to figure out its inflorescence check if it is Rasmus or Symos. So now we have quite a lot of confusing terms right? Rasmus, Basipetal, Symos, Acropetal how do you remember which is which? Well I like to use something called word associations to remember these terms and this works for me and you can come up with your own word associations to remember the meanings of these terms. Let's take a look at Rasmus first. So the word Rasmus has the word race in it and what happens in a race? We run to see who can finish first right? So I'd like to think that in Rasmus inflorescence the flowers are competing against each other to see who can be on top who can be on the topmost part of the stem and what happens in a race when old people like your grandparents try to compete against you? Well you're more faster than your grandparents right? You will obviously win the race. So you can think of as Rasmus as newer flowers racing against older flowers and then winning and coming on top of the older flowers. Well this is how I'd like to remember Rasmus as being newer on top and older at the bottom and Rasmus also has the word acropetal in it. Acropetal also means newer on top and older in the bottom. The word acropetal can be associated with the word acrobat and have you seen acrobat in circuses? They like to jump high in the circus right? They jump high and they do all sorts of stunts and usually acrobats are people who are young. Old people like your grandparents cannot be acrobats right? So in the case of acropetal I'd like to remember the word acrobats in which the newer flowers are the acrobats that jump high in the air and the older flowers are the older audience, your grandparents and my grandparents were sitting in the audience and watching these acrobats do incredible stunts. That's how I'd like to remember the word acropetal to mean newer on top and older at the bottom. What about Psymos now? So Psymos remember is where the older flower is on top and the newer flowers are at the bottom. The word Psymos has the word Psy in it and Psy is what the older people in your house your parents, grandparents do when they're disappointed in you right? You sit below them on the floor and they're standing and they're looking at you with a disappointing look and saying Psy, you've done it again. That's how I'd like to remember that the older flowers are on top and we, the younger flowers, the younger people are sitting below them on the ground. That's how I'd like to remember Psymos with the word Psy. Now what about the word basipetal? Now I'd like to think that basipetal has the word boss in it or it sounds similar to the word boss and who's the boss in our house? It's always our parents right? It's always the elders who are the boss in our house. That's how I'd like to remember basipetal as the older flowers being the boss, they're on top and in the hierarchy, the newer flowers that's us younger people, we're below them. That's how I'd like to remember basipetal to mean older on top and newer at the bottom. You can come up with more quirky, weird word associations that you can use to remember terms not just in biology but in all other subjects. Cool isn't it?