This is a little out of date but I may as well post it.
The harvest of water caltrop and hairy golf ball sized taro also heralds the coming of
mooncake festival. At home, we called the water caltrop bull horns (ngau kok/lin kok). A fter boiling (around 30 min), cracking the
intimidating black husk reveals a powdery white kernel. The husk has a
somewhat strange odor that would call to my mind the unattractive waft of steaming horse poo. Nobody else ever remarked on this association perhaps this is only true for me. Fortunately the smell doesnt translate
to the meat which is very starchy and has a lovely woody/rooty taste. Personally, the delight of water caltrops lies as much in their novel appearance, rare annual appearance, and the battle to remove it, as it does in their tasting.
Water caltrop is an odd crop indeed. There is little information I can unearth on it and wiki seems to provide the most information yet (in a broad overviewy sense). Besides general consumption and the fun of it, the water caltrop has seen use in India as a remedy for stomach issues and in poultices (I). Water caltrop starch can be found in supermarkets and is used in cooking to thicken soups and sauces. However, this is not made from water caltrop at all, but water chestnut starch (bad people are being confusing by mixing the two). More likely, you may unwittingly end up eating caltrop starch in ice cream-
its substitution for cornstarch in ice cream 'improver' powders (2)
results in a creamier and smoother product. Apart from its edible nature, an
investigation into the properties of its starch suggests caltrop starch could be
used for textile sizing, due to its viscosity being little affected by
temperature over a large range, tests for which have already been performed confirming this (3).
My grandmother also used to make the most amazing toy out of water
caltrops for us too. Many an hour used to be spent trying to core a
caltrop and whittle down a
chopstick to make a deadly spinning caltrop weapon. I meant to
make one with this year's harvest but haven't had the time yet. For now
my caltrops will wait in the freezer.
I am pretty sure most people know taros, what with the rage of taro flavoured puddings and taro bubble tea floating about the world, so I won't bother with giving them an introduction. Please note that these are taros not yam (I shall be posting a photo of a yam in a bit when I get around to typing out my recipe for a yam cake). Traditionally, we would boil the taros skin on, after which the skin slips off nicely leaving its steaming white flesh to be dunked in sugar and eaten. Winner!
(1) Badel, Powel, “Punjab Raw Materials,” 1868.
(2) Food, 6, 40 (1936)
(3) Shafee, Sarin, "Production of Starch from Water Caltrop," Ind. Eng. Chem., 1937, 29 (12), pp 1436-1438