Duck Potato Salad

Walking around a freshwater marsh, we can observe dozens of plants and animals.  Daily sunlight provides hours of energy, but it is only usable by the plants, which create their own food in a process called photosynthesis.  Plants may be fully submerged, floating, or living above the water’s surface, but all are vital components of the food supply.

Just as animals breathe, plants also need to exchange gases, taking in carbon dioxide and releasing oxygen.  Plants living in a marsh, where they are fully or partially saturated with water, have developed several strategies for the gas exchange process.  Spongy tissue is a universal adaptation of marsh plants.  Both stems and leaves contain large airspaces surrounding food producing cells which are well distributed throughout the plant.  Airspaces also keep the plants lightweight and enable stems, leaves and flowers to float on or reach above the water’s surface. 

Floating wisps of green algae are primitive plants that have been on earth for over two billion years and are the basic food source for all life in the marsh.  Millions of microscopic animals, crustaceans, insects, and small fish depend directly on green algae for their food.  Green algae lack stems, leaves and flowers, but grow as long chains of nearly identical cells.  Some algae are microscopic, some can be easily observed as green strands on or below the water’s surface and some grow to several hundred feet in length.

Duckweeds refer to a group of tiny, flowering plants that float on the surface of wetland areas.  They  reproduce by dividing their cells.  This is a rapid process taking from 16 to 48 hours.  In optimal growing conditions, with plenty of sunlight and nutrients available, the surface area of a pond can be covered in a very short period of time.  Several species of pond plants grow long, narrow leaves with soft, nourishing cells providing a easy-to-eat and tasty treat for marsh dwellers.  With large airspaces, these plants are able to stay afloat no matter how long they grow.

Plants with floating leaves, such as spatterdock, must have a method for preventing excess water from entering leaves and stems when they exchange gases.  Plants have stomata, openings in the leaf where gases are exchanged.  In terrestrial plants, stomata are located on the undersides of leaves to prevent rain from entering the opening.  Floating leaves have stomata on the upper side of the leaf, providing far less exposure to water.

Water marigold has two types of leaves, one that grows on the stem above the water’s surface and another that grows on the submerged stems.  Leaves growing in air take in carbon dioxide and release oxygen through their stomata.  Submerged leaves have very thin cell walls and exchange the same gases directly with the water surrounding them.

Arrowhead is firmly anchored in the bottom of ponds, and has stems, leaves, and flowers growing above the surface.  It reproduces by both seeds grown from pollinated flowers and bulbs grown on submerged stems.  Bulbs remain submerged, attached to the stem and grow until they are mature enough to anchor themselves in the bottom silt and start another plant.  While growing, the bulbs are very tasty and are a favorite food of many duck species, earning the nickname duck potatoes.

Wild celery produces both male and female flowers.  Female flowers are attached to long stems that float on the water’s surface.  Male flowers break off underwater and float to the surface unattached, where they are blown around until they meet a female flower, transferring pollen by contact.  The pollinated flower coils downward back under the surface where the seeds develop and are released into the water to start a new plant wherever they land on the silt bottom.

Marsh plants come in many forms and each is well adapted to the unique conditions of the habitat in which they live.