Saltrees are the descendants of saltbushes, more specifically the garden orache (atriplex hortensis). The saltbushes that we have now are vegetables that can be found practically everywhere due to human introduction.
Evolution of Saltrees
Saltrees arose after the holocene and survived due to a tolerance for high temperatures. Since most coastal trees went extinct during the holocene extinction, the ancestors of saltrees took the niche. Since oraches were already tolerant of salty soil it wasn't much of a problem for them to adapt to the coasts and eventually, saltwater. They developed a woody stalk and branches like most other trees, the also developed very mangrove-like roots to deal with the tides.
Biology of Saltrees
Saltrees can be pollinated by both wind and animals. When pollinated, their seeds are diamond shaped. The top portion of the seed (the base) is buoyant and floats for a few hours before getting waterlogged and sinking. The bottom portion of the seed sticks itself into the sediment and currents combined with animal movement drill the seed into the ground and bury it, this usually takes place over a week.
Much like mangroves saltrees have aerial roots that branch down into the soil and process gases from the air. These roots also have a salt filtration system that can tolerant a salinity level approximately 3.5 times the salinity of the ocean. This higher salinity tolerance lets saltrees spread farther and easier than mangroves could have.
Saltrees have small spinach-like leaves with pointed ends. The roots spread at least 35 feet wide in diameter and the height from trunk to crown measures at least 20 feet. Saltree roots grow together in mats.
Ecological impacts of saltree forests
Saltree forests are a hotspot for biodiversity with a multitude of different species depending on them for survival, many species are also endemic to saltree forests. Saltrees provide protection from the harsh storms that come with high amounts of greenhouse gases. Saltree forests absorb high amounts of co2 but a carbon sink isnt formed due to predation by herbivores.