A large floating plant

rebel

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@alto, we have certain plants that are declared weeds in only some states in Australia.
 

dw1305

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Hi all,
I was rather surprised to see it legal for trade in the U.K.
It is because it doesn't get a warm enough in the summer to reliably set fruit in the UK.

It is native to the warmer bits of Europe, and not invasive there, in fact quite the opposite it is endangered in S. Germany etc.

We know from the fossil record <"that T. natans was found in the UK"> during some of the inter-glacial periods, when the weather was warmer (a long with Pond Terrapin, Green Frog etc.).

cheers Darrel
 

alto

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is because it doesn't get a warm enough in the summer to reliably set fruit in the UK.
I looked at average annual temperatures for London U.K. Vs Ottawa, Ontario - seems a surprisingly small difference in summer temperatures for such an impact
(not doubting you :))


Ottawa
January -6° / -14°
February -4° / -13°
March 2° / -7°
April 11° / 1°9
May 19° / 8°
June 24° / 13°
July 27° / 16°
August 25° / 15°
September 20° / 10°
October 13° / 4°
November 5° / -2°
December -2° / -10°

London
January 9° / 4°
February 9° / 5°
March 12° / 6°
April 15° / 7°
May 18° / 10°
June 21° / 13°
July 23° / 15°
August 23° / 15°
September 20° / 13°
October 16° / 10°
November 12° / 7°
December 9° / 5°
 

dw1305

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Hi all,
seems a surprisingly small difference in summer temperatures for such an impact
London has a real <"urban heat island effect">, so there are exotic plants present that don't survive in much of the UK. In most years Central London is pretty much frost free in the winter. It was here as a native in the Holocene, so it might not need much warmer summer temperatures for it to establish.

I don't know, but it might be a sunshine issue. Our summer is fairly cloudy and we don't tend to get long periods of settled fair weather, it tends to alternate with cooler periods with wind and rain. Also it is doing poorly as a species even in the warmer bits of Europe, so there is probably something else going on.

I'll see if I can find out if there are London records of Trapa natans, as an established exotic.

cheers Darrel
 

zozo

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I've tried this plant several times in the garden during the summer periode. My tub is most part of the day unshaded. Till now it failed every single time to make it thrive it always slowly fauled away. It is a very demanding sp. and absolutely likes a warm sunny and a nutrient rich invironment, reportedly slight acidic somewhat calcareous and preferably shallow stagnant waters with loamy soils. Should be indigenious in western Europe but in our country on the red list and is about completely dissapeared in nature, last reported observation in the wild was 1908. In all of Europe in the warmest southern regions it is a rarety in for the rest considered about extinct. Which is rather strange, since the climate only got warmer since. Till the first half of the previous century it even was found as far north as Sweden.. No clue what has changed in the Western Europes invironment to make it dissapear in nature, it must have a reason but nobody knows why.. Since it's a anual plant, that drops nuts that need to overwinter frost free to germinate again.. Becomming endangered in regions where it always used to grow, might simply be an indicator of a plant very sensitive to (Underwater) soil pollution. In know in my country 90% of the water rich nature reserves are highly poluted, most people who just go there for a walk don't know, but the Angler is adviced not the eat the fish they catch there.

Good luck for those who like to grow in indoors.. You beter EI to the max.. You're in for a challange. :thumbup: If you succeed you got a darn beautifull plant.. :)
 

alto

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I'd send you some but wrong side of the country :p

No shortage of Purple loosestrife (Lythrum salicaria) or Eurasian watermilfoil (Myriophyllum spicatum) though ;)
 
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I killed my trapa natans too but before I became its owner, it looked absolutely stunning and that picture in the link in the first post doesn't do it justice. I am almost tempted to give it another go...
 
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Some info below, looks like its not an easy one to grow...

Can You Grow Water Chestnuts?


Growing water chestnuts are primarily cultivated in China and imported to the United States and other countries. Rarely, have attempts been made to cultivate in the U.S.; however, it has been tried in Florida, California and Hawaii with limited commercial success. Water chestnuts require controlled irrigation and 220 frost free days to reach maturity. Corms are planted 4-5 inches deep in soil, 30 inches apart in rows, and then the field is flooded for a day. After that, the field is drained and the plants are allowed to grow until they are 12 inches high. Then, once again, the field is flooded and remains so for the summer season. Corms reach maturity late in the fall wherein the field is drained 30 days prior to harvest. Water chestnuts cannot exist in swamplands or marshlands unless ditches or dikes are in place to control the water levels. That said, the question, “Can you grow water chestnuts?” takes on a bit different meaning. It’s unlikely that the home gardener will have much success growing water chestnuts. However, don’t despair. Most grocers of any size carry canned water chestnuts to satisfy that yen for some crunchiness in your next stir fry.

Read more at Gardening Know How: Water Chestnut Facts – Can You Grow Water Chestnuts In Gardens? https://www.gardeningknowhow.com/edible/vegetables/water-chestnuts/water-chestnuts-in-gardens.htm
 
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It looks like they need to be rooted to start with and then the water level needs to be controlled...
 

zozo

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It looks like they need to be rooted to start with and then the water level needs to be controlled...
Yes they are anual plants and die off in the winter, the nuts sink to the bottom, if the water is deeper than 50cm it might never resurface again. So under correct condition in about 50cm or less the nuts germinate if not to much damaged by heavy frost and thus the plant starts out rooted.. The mature plant might break off and float away and leave it's nuts somewhere else in the fall. :)

I guess the draining they advice is only to have some control over what going on and or give the young plant enough light if the water aint clear enough.

This also could be a reason why it is about extinct in the waters from western europe.. As said above polution, cuases less plant growth.. Or authorities take out vegitation mechanicaly to free the water ways.. Cause of minimal to no aqautic vegitation is murky water with very little light penetration. Look for example to local park pools where angler clubs are active, they hate aqautic plants because it prevents them fom properly catching fish t tangles their lines. All the plants taken out and have murky water.. Natural pools without active an angler club, have aquatic vegitation and crystal clear water. Since western europe is over populated and regulated in every corner very little of these waters are still present. If not poluted it is regulated/maintained, mother nature has no chance to do what she needs to do..
 

sparkyweasel

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That info on cultivation is for true Water Chestnuts, Eleocharis dulcis, as found in your Chinese take-away. Trapa natans is usually called Water Caltrop, although some people apparently call it Water Chestnut, which is confusing. :)
E. dulcis is like a huge version of the various types of Hairgrass we know and love, which are also Eleocharis, of course.
Water Caltrop has a long stalk, ten or twelve feet long, anchored in the substrate. Roots in the mud can take up some nutrients, and the stem has fine leaves which can take nutrients from the water column. The floating leaves are good for CO2 uptake and photosynthesis, not so good for nutrients. They also support the flowers above the surface, where they are pollinated by flying insects. Without the stem, side leaves and roots it will struggle. It might be worth trying a foliar feed, but I haven't tried yet.
 

alto

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Can You Grow Water Chestnuts?

Growing water chestnuts are primarily cultivated in China and imported to the United States and other countries. Rarely, have attempts been made to cultivate in the U.S.; however, it has been tried in Florida, California and Hawaii with limited commercial success. Water chestnuts require controlled irrigation and 220 frost free days to reach maturity. Corms are planted 4-5 inches deep in soil, 30 inches apart in rows, and then the field is flooded for a day. After that, the field is drained and the plants are allowed to grow until they are 12 inches high. Then, once again, the field is flooded and remains so for the summer season. Corms reach maturity late in the fall wherein the field is drained 30 days prior to harvest. Water chestnuts cannot exist in swamplands or marshlands unless ditches or dikes are in place to control the water levels. That said, the question, “Can you grow water chestnuts?” takes on a bit different meaning. It’s unlikely that the home gardener will have much success growing water chestnuts. However, don’t despair. Most grocers of any size carry canned water chestnuts to satisfy that yen for some crunchiness in your next stir fry.
This portion of the (somewhat confusing) article actually refers to Eleocharis dulcis which is the commonly available "Chinese water chestnut" (rather than the "European water chestnut")
 
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