This is Ipomoea aquatica, in Bengali- Kalmi, leaves taken as green
vegetable. It is aquatic in habit. But this particular plant is
growing in dry land.During the last monsoon this land became
waterlogged for few days, and the Ipomoea grew there. After monsoon
the land was cleared, but last month I found a single plant coming
out. A few days back I found a bud, the bud opened at about 10.00 am
in the morning. and again closed in the evening. First of all the
aquatic I. aquatica flowers are light violet in colour, but not this
one. Moreover, unlike other white flowers (as in I. alba) it opened in
the day time and closed with the sunset. It is just an observation to
share with you.
Place- Prantik (Shantiniketan), date - 27th Nov. 2008
Ipomoea aquatica is a semi-aquatic tropical plant grown as a leaf vegetable. Its precise natural distribution is unknown due to extensive cultivation, with the species found throughout the tropical and subtropical regions of the world.
Common names include water spinach, swamp cabbage, water convolvulus, water morning-glory, Thooti koora in Telugu; Kalmisag, Sarnali, Ganthian in Hindi ; In Assamese it is called Kolmou; In Bangla Kolmi Shak or Kolmi Lota.
Ipomoea aquatica grows in water or on moist soil. Its stems are 2-3 m or more long, hollow, allowing them to float, and these root at the nodes. The leaves vary from sagittate (typical) to lanceolate, 5-15 cm long and 2-8 cm broad. The flowers are trumpet-shaped, 3-5 cm diameter, usually white in colour.
It is most commonly grown in East and Southeast Asia. Because it flourishes naturally in waterways and does not require much if any care, it is used extensively in Malay and Chinese cuisine, especially in rural or kampung (village) areas. It is not to be mistaken with watercress, which often grows in similar situations.
Other good links: http://aquat1.ifas.ufl.edu/node/201, http://www.lucidcentral.com/keys/FNW/FNW%20seeds/html/fact%20sheets/Ipomoea%20aquatica.htm, http://www.hear.org/pier/species/ipomoea_aquatica.htm