Mangroves survive in seawater with a salinity that would be lethal to most trees and shrubs. Like celery or carrot sticks placed in saltwater, the roots of most plants rapidly lose water if they are suddenly emersed in seawater. Halophytes (salt-loving plants) such as mangroves generally have a lower concentration of water molecules (lower water potential) in their root cells so they can take in water. They maintain lower water potentials in their roots by having higher internal salt concentrations than seawater and by losing water at the leaf surface. Since high internal salt concentrations can be lethal to plant cells, some species such as the black mangrove and white mangrove (Laguncularia racemosa) can excrete excess salt through special glands in their leaf blades and petioles. Red mangroves have root cell membranes which prevent the absorption of excess salt.

In China, the syconia of creeping figs are picked ripe and placed in a porous bag to squeeze out the juice. The juice is cooked and then cooled into a gelatinous consistency called "pai-liang-fen." This jellylike material is cubed, mixed with water, syrup and flavorings and consumed as a refreshing drink. It is canned and sold in Asian markets as "grass jelly" of "ai-yu jelly." According to Cornucopia II by S. Facciola (Kampong Publications, 1998), boiled plants of Mesona chinensis in the mint family (Lamiaceae) are also made into cubes of grass jelly. In fact, cans of grass jelly often list this species on the labels.