Maine Nature News – Water Lilies

by Fred Gralenski

Things were getting a little out of hand in August. I like Maine the way it’s supposed to be, sort of cool and damp. However it seemed a little degrading that we needed tropical storm Earl to bring much needed rain to the Quoddy region.  Well, Earl is a good Maine name, and we had to have rain, so I suppose it’s OK.  Along with my admiration of water is my admiration of plants that grow there, and pretty high up on my list is the water lilies.  We typically have two kinds of water lilies in the ponds and swamps around here: the white Fragrant Water Lily Nymphaea odorata and the Yellow Pond Lily Nuphar lutea.  The latter flower had several species and associated scientific names, but apparently N. lutea is now the one.
Alas, the season of our Fragrant Water lily is almost over.  In the early summer on some calm day kayaking on a shallow pond like Great Works in Edmunds, if the bugs aren’t too bothersome, the scent is very agreeable.  Thoreau, in one of his many journals, wrote that he thought the sensation was, “…as wholesome as the odor of a cow.” I usually agree pretty much with what Thoreau wrote, and  generally I like the scent of any animal (except a dog that has found something really scanky to roll in), but comparing the odor of a water lily to a cow is a stretch.  Maybe the redeeming word is ‘wholesome’.  By mid afternoon even on sunny days the water lilies close up their blossoms, as if they don’t want to welcome any evening or night critters.  They are visited during the day by a host of pollinating bees and other insects, but may be very initially visited by a resident long horned leaf beetle that is thought to cause self fertilization of the lily.  Some scientists consider this process as a backup to normal cross pollination.  Water lilies also have some other tricks.  All green plants need to breath, to ‘inhale’ carbon dioxide, and by way of photosynthesis, produce food.  Terrestrial plants do this with tiny pores on the bottom of their leaves called ‘stomata’, and water lilies have the stomata on the top of their leaves to accomplish the same thing. Scientists investigating water lilies have determined that the age of the leaves give them different jobs in the lifestyle of the plant and the younger leaves do most of the inhaling to supply the rhizome (which is usually sunk in anaerobic muck) with air and the older leaves do most of the exhaling.  Another aspect of the leaves is why are they always round?  Some theories are that terrestrial plants have better luck at shaking off insect pests and have evolved with leaf forms to better accomplish this.  Water lily leaves are more subject to abuse from waves and airborne projectiles, so apparently a round shape is more rugged and satisfactory under those conditions.  The lily leaves also need to float.  Another feature is that the Fragrant Water lily and the Yellow Pond Lily usually don’t exist together.  It is thought that temperature, pH, disturbance and oxygen concentration may be factors.
And finally, are these plants good for anything besides show?  The big rhizomes are eaten by muskrats, moose and it seems like anything else that can get them.  Native Americans pounded the roots into a mush and used that as a poultice for bruises and swollen limbs.  Harvested in the fall, the rhizomes are rich in carbohydrates and used as a flour when dried. They can be boiled like potatoes, but must be rinsed and cooked several times to rid them of the bitter tannins.  The young leaves can be cooked as a green vegetable in the spring, but one reference stated that the Yellow Pond Lily may accumulate toxic levels of cadmium under some conditions.  That was probably downstream from where they dumped the last load of Ni-cad batteries when they changed to Lithium-ion.