Cymose and Racemose — Definition
Definition
Imagine a plant's stem, but instead of just leaves, it's adorned with flowers. The way these flowers are arranged on the main stem (or a specialized branch) is called an 'inflorescence'. It's like how beads are strung on a necklace – the pattern matters! In botany, this pattern helps us understand how a plant grows and reproduces. There are two big families of inflorescence patterns: Racemose and Cymose.
Let's start with Racemose Inflorescence. Think of it as an 'ever-growing' flower stalk. The main axis, which is the central stem holding the flowers, just keeps on growing and producing new flowers.
It doesn't stop its growth by forming a flower at its tip. Because the main axis keeps growing upwards, the oldest flowers are found at the bottom, and the youngest, newest flowers are at the top, closer to the growing tip.
This arrangement, where younger flowers are at the apex and older ones at the base, is called 'acropetal succession'. It's like building a tower from the bottom up. The flowers also open in this sequence, from bottom to top.
Plants like mustard, radish, and gulmohar show this type of arrangement. The main axis is said to have 'indeterminate' growth because its growth isn't fixed or limited by a terminal flower.
Now, let's look at Cymose Inflorescence. This is the opposite! Here, the main axis is 'determinate', meaning its growth is limited. Why? Because the very first flower that forms appears at the tip of the main axis.
Once the tip forms a flower, the main axis can't grow any further upwards. So, if the plant needs more flowers, new flowers have to grow from the side branches, below the terminal flower. This means the oldest flower is at the top (the one that stopped the main axis's growth), and the younger flowers develop below it, on the lateral branches.
This sequence, where younger flowers are at the base and older ones at the apex, is called 'basipetal succession'. It's like building a tower from the top down, or perhaps more accurately, like a family tree where the 'parent' flower is at the top, and 'children' flowers branch out below it.
The flowers also open in this sequence, from top to bottom. Plants like jasmine, cotton, and Bougainvillea often display cymose inflorescences. So, the key difference is whether the main axis keeps growing or if its growth is 'capped' by a flower.