the life of the water lily

While taking photos of the orangutans at Como Zoo the other day, I noticed they had quite a nice exhibit of a variety of water lilies growing in the ponds in front of the building.

Pointing their fragrance-producing flowers upward to attract pollinators above the widespread leafy surface — these amazing White Water Lilies have some interesting adaptations for survival.

Admiring the floral display got me to wondering how a plant that has its roots deep in mucky sediment along with the lower surface of its leaves completely submersed in water gets enough oxygen to grow such huge leaves and large, elaborate flowers.

The large, ovate leaves serve two purposes — trapping carbon dioxide to fix carbon into the structural sugars that build leaves and flowers AND sequestering and transporting oxygen through the upper surface down tubes in the leaf stem to the roots.

Leaves of the Giant Water Lily can be 4-6 feet across, and strong enough to support the weight of a mammal walking across them. Their undersides are ribbed to trap air that helps them float, and the ribs are adorned with thorns that discourages fish or insect herbivores from munching on them.

Flowers are ephemeral, lasting just a few days, but have a unique strategy for ensuring pollination.  Typically, they open only for a few hours in morning or evening hours and close the rest of the time.

Newly emerged flowers produce an enticing fragrance when they first open, attracting beetles, and some bees.  Only the female stigma is exposed at this time, and the insects crawling around on its surface looking for nectar leave pollen collected from other plants to fertilize that flower.  There might be so much fluid at the base of the flower, the pollen is actually washed off the insect onto the stigma.

But then the flower closes up, trapping insects left behind, and it remains closed while the flower’s anthers open and dump their pollen all over the trapped pollinators.  Nectar and fragrance production stops, motivating trapped pollinators to fly away when the flower re-opens.

When flowers open again the next day, or a day later, pollinators freshly dusted with the flower’s own pollen fly off to seek out other, newly, opened lilies that have nectar.

Pollinated flowers close again, and are pulled down under the water while seeds develop.  Eventually the seed pod opens to disperse its ripe seeds to the mucky sediment, and the cycle begins all over again.

The life cycle of the Giant Water Lily is wonderfully described by David Attenborough in his video of The Private Lives of Plants — you can view a 4 minute clip from this by clicking on the link below (there may be a short, but annoying 5 second ad preceding the video).