SEASIDE HALOPHYTESOne of the treats of being in the tropics is that often you see plants and animals obviously related to species you know up in the Temperate Zone, but the species down here behave differently from their northern cousins. For instance, some plant families that produce mostly or entirely herbaceous species in the North, down here may manifest themselves as woody shrubs and trees. Tropical beaches can twist your mind even more. For, added to the tropical consideration is the fact that organisms growing next to or in saltwater often produce odd growth forms to deal with the salt. You know that if you spill salt on your lawn it'll kill the grass. The reason has to do with the fact that if the water outside a plant or animal cell -- outside the cell's semipermeable membrane -- is saltier than inside the cell, that water will stay outside the cell and the plant roots will be unable to absorb water. In salty soil such as that at the beach, plants have a serious problem getting water into their bodies. Plants that have evolved special features enabling them to survive in salty soil are called halophytes. A large percentage of halophytes are succulent in nature. Therefore, on a tropical beach it's fun to look for plant species that not only are woody, though Northerner would expect members of their family to be herbs, but also succulent or semisucculent. That's exactly the case with one of the most common and conspicuous woody bushes standing about chest high along the beach next to Hotel Reef. For a long time I wondered what this strange-looking shrub was and when finally I found a flowering plant what a surprise it was to see that the plant was clearly a member of the Borage Family. Northerners think of the Borage Family as a family of herbs – remembering members such as bluebells, comfrey, heliotrope, forget-me-not, hound's-tongue and garden borage. The beach shrub was Sea Rosemary, TOURNEFORTIA GNAPHALODES, similar to what you can see at http://www.baobabs.com/Tournefortia%20argentea.htm. It was a similar case with a woody shrub with hand- sized, orbicular, succulent leaves, and fruits resembling clusters of grapes. It was Sea-grapes, COCCOLOBA UVIFERA, also common here, to be seen at http://www.botany.hawaii.edu/faculty/carr/images/coc_uvi_mid.jpg. A succulent, halophytic member of the Mustard Family flowering along the beach now is CAKILE EDENTULA. Its turgid leaves are so crisply juicy and salty that I snack on them as I walk along the beach. You could make a decent salad of just this plant's leaves and a bit of salad dressing, and maybe some tomato chunks and a bit of garlic. It can be seen at http://botit.botany.wisc.edu/images/veg/Cliffs_Dunes/Cakile_edentula_VK.php. |
