Sunken Gardens of Salt The Strange Science of Mangroves and Tidal Forests

Pick a leaf from a grey mangrove, touch it to your tongue, and it tastes of salt. Sometimes you can see the reason before you taste it: a fine white dusting of crystals on the leaf surface, left behind like frost on a window. The tree has been drinking the sea, and this is what it does with the part it cannot use.

That should sound wrong. Almost every tree you know would die if you watered it with the ocean. Salt water pulls moisture out of plant roots instead of delivering it, and whatever salt does get inside poisons the cells. Farmers know this well, and a field flooded with seawater can be ruined for years. Yet along tropical and subtropical shorelines, from the river mouths of Australia to the deltas of South Asia and the coasts of West Africa, there are forests that stand with their roots in tidal water twice a day. They are called mangroves, or tidal forests. The name does not describe one family of trees. It describes a way of making a living, one that unrelated plants arrived at separately, in a place where most plants cannot survive.

This episode is about how they do it. It covers the salt, the missing oxygen, and a seedling that begins growing before it has even left its parent. It also covers what these forests quietly build around themselves, and what happens as they are cleared and, in some places, painstakingly replanted.