Jhanjhi or Water thyme (Hydrilla verticillata, Hydrocharitaceae) is many branched submerged herb with slender stem. The aquatic plant is treated as weed to paddy field in Bangladesh. It is found abundantly in river, haor, canal, beel-jheel and pond in the country.
Other Bangla names: Kureli, Kanjal.
Leaves are green, linear, sometimes having reddish dots or dashes on them, .5-2 cm long, serrate, pointed apex, sessile. Male spathe axillary in one or all leaves of a whorl. Male flowers born in spathe in single. Sometimes
Flowers can be seen floating in the water when released from the spathe; perianth reddish white. Female spathe with apex, shortly bidentate, perianth slender,long, tubular. Flowering occurs in winter.
Fruit is echinate, smooth or soft. Seeds 2-6, ellipsoid, glabrous, dark brown. The plant is propagated by seeds. It is found in South and Southeast Asia, East Europe, Africa and Australia too.