First of all, i would like all of you to know that there are basically 5 major classes of plant hormones,namely :
1.abscisic acid
2.auxins
3.cytokinins
4.ethylene
5.gibberellins
Each and every one of these hormones play a very specific and vital role in carrying out the plant's day to day functions. So in other words, they are extremely important and any abnormalities might lead to dire consequences.