"Kaash is a perennial grass, though it looks like a flower which is why it is called ‘kaash phool (flower in Bengali)’, growing up to three meters tall, and found in the Terai-Dooars grasslands across India, Nepal, Bangladesh and Bhutan. In Bengal, the grass typically grows on exposed silt plains of rivers created by retreating monsoon floods. Which means they appear each year in September-October, Durga Puja season.
It is perhaps owing to this that the beautiful silvery white strands of kaash have become so integrally associated with Durga Puja festivities. To the extent that very often, artists’ impressions of Durga Puja consist simply of a few silken stalks of kaash, and goddess Durga’s face. The appearance of kaash phool signals a change in the weather, with the skies a clear blue after the rains, and fluffy white clouds forming the perfect backdrop for the lovely white ‘flowers’. Just check out the thousands of kaash flower images on the net for proof. "