Cacti and Agave in St Lucia (Warning: Lots of images)

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Re: Cacti and Agave in St Lucia (Warning: Lots of images)

Post by IanW » Wed Mar 09, 2016 10:24 pm

Hi Ray, I'm actually convinced that at least some of the plants here (though mostly the Pilosocereus) get the vast majority of their water from sea spray. Some are growing in solid rock underneath overhangs and it's hard to see how much rain could really reach them whilst simultaneously they were being hit by constant splashes from the crashing waves.

On the rocky outcrops that were separated from the mainland on which the sole inhabitants were Pilosocereus the waves were actually reaching up and washing over the surface on which those Pilosocereus were growing meaning they must be almost constantly living with their roots somewhat damp from salty water.

What this means for cultivation I'm really not sure. Is it possibly the case that some species might actually benefit from some salt water? That seems incredibly unlikely and yet here are some of those plants thriving in exactly those conditions and in fact on those outcrops they were the only things that appeared able to live there at all. Is it possible they have some mechanism to filter out the salt? I'm not sure, it's something I know nothing about. It'd be interesting to hear people's theories on whether this could be somehow beneficial, or whether they somehow avoid the salt intake altogether.
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Re: Cacti and Agave in St Lucia (Warning: Lots of images)

Post by RAYWOODBRIDGE » Thu Mar 10, 2016 11:01 am

Hi Ian. yes living on the Lancashire coast, we have several types of grass, shrub and pine that thrive on a salty environment, while other plants will only grow 2 or 3 miles inland any nearer to the sea and they soon die off.
Photos of Melocactus on or very near to Caribbean beaches is not uncommon. I cannot believe the plants look for or need salt, but they obviously have a way of dealing with it, both in the root system and the dried salt which must be on the body of the plant.
Pilosocereus and Harrisia may also be a group of cacti able to deal with salt.

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