The State Flower is The Golden Shower Tree or Indian laburnum Cassia locally known as Kanikkonna in the family Fabaceae, native to southern Asia, from southern Pakistan east through India to Myanmar and south to Sri Lanka. The flowers are of ritual importance in the Vishu festival. The medium-sized tree blooms in a particular season during the Medam month of Malayalam calendar (April - May), when Keralites celebrate Vishu.It is a medium-sized tree growing to 10-20 m tall with fast growth. The leaves are deciduous or semi-evergreen. It is widely grown as an ornamental pla nt in tropical and subtropical areas. It blooms in the month of May; flowering is profuse, with trees being covered with yellow flora, with almost no leaf being seen. The golden shower tree is the national flower of Thailand and is called Dok Khuen; its yellow leaves symbolize Thai royalty. 

Kerala Gazette No. 12 dated 20th March 1990