Red Mangrove with nearly mature propagules in front of Duck Key, FL.

It’s that time of the year again in the Florida Keys. Summer is all but here and the red mangroves (Rhizophora mangle) are almost ready to drop their mature propagules (a seed pod if you will). These propagules are quite unique in that they become fully formed “plants” even before they fall off the tree (They have already germinated while on the tree itself). When mature, they drop into the water below and float iceberg-style, carried to new locales by water currents, wind, tides, and storms. In ideal circumstances the propagule eventually finds a soft bottom in which to take root. The leaves form from the top of the propagule. Eventually it will produce the iconic mangrove prop root “legs” that help facilitate gas exchange and structural support.

This form of reproduction makes propagating mangroves in saltwater aquaria a relatively easy task. All they need to grow is for the top 1/3 of the propagule to be above the water surface, bright light, a deep sand bed, and occasional “mistings” of freshwater from a spray bottle to wash off built-up salt deposits. These are trees of course, so expect them to eventually grow quite large.