The present investigation is on the physico - chemical parameters and the diversity, distribution and abundance of mangrove vegetation at Poyya backwaters of Thrissur district, Kerala, India. The hydrographic parameters fluctuated with sites. The temperature ranged from 25 to 31°C and total hardness from 30 to 52 mg l-1. The pH of water was generally alkaline and the values varied from 7.03 to 7.34. The salinity of water ranged from 19.88 to 31.24‰ during premonsoon season and 19.88 to 28.4‰ during monsoon season. During the period of study four true mangroves belonging to four genera were observed from three sites. The true mangrove species were Aegiceras corniculatum (L.)Blanco, Avicennia officinalis L., Acanthus ilicifolius L. and Excoecaria agallocha L. Acanthus ilicifolius L. was the dominant and abundant plant followed by Avicennia officinalis L. The mangrove associates were Derris uliginosa (Roxb.) Benth, Clerodendron inerme (L.) Gaertn, Sphaeranthus indicusL., Achrostichum aureum L., Mariscus javanicus (Houtt.) Merr. & Metcalfe and Cyperus species. The diversity index of the mangrove and associated flora in Poyya backwaters was 3.1 in site 3 and 2.4 in sites 1 and 2.

Mangroves, Poyya backwaters, hydrographic parameters, diversity index