Waterlily Flowers

While watching birds at St. Marks NWR, I try to observe their behavior in order to better understand them. I’ve noticed that in later winter as they undergo hormonal changes that prepare them for the breeding season, Yellow-rumped Warblers become more territorial and begin chasing other birds. I’ve seen that wintering shorebirds at high tide are usually resting, but shorebirds in Spring migration are constantly feeding in order to add fat to fuel their Northward flight.

Lately, I’ve been looking at how birds use plants. Cabbage Palm’s abundant berries provide food from September through February for woodpeckers, thrushes, Yellow Warblers, Robins, Catbirds and Mockingbirds. Winged Sumac berries are primarily a late winter food for Yellow-rumped Warblers, Cardinals, sparrows and Hermit Thrushes.

However, sometimes I find myself fascinated by the plant itself. White Waterlilies are common at St. Marks. Blooming from February through November, their fragrant multi-petalled flowers float on the water’s surface among the wide, dark green lily pad leaves. Each lily pad and flower is connected by a stem to a network of shallow roots, called rhizomes, in the mud below. White Waterlilies can grow in water as deep as six feet and do well in the refuge’s shallow freshwater ponds and pools. 

White Waterlily flowers contain both female and male parts. The female pistils are attached to seed-producing ovules that can be fertilized by pollen from the male stamens. Each five-inch-wide flower exists for only three days, during which it will open in the morning and close in mid-afternoon. 

On the first day of blooming only the female parts of the flower are active and the flower is only partially open, forming a cup filled with clear nectar that provides a reward for visiting insects. That first day is the only day that the flower will produce nectar and have pistils receptive to pollen. Pollen grains are sticky. Pollen grains stuck to an insect that has visited a pollen-producing White Waterlily flower will wash off in the pool of nectar and be absorbed by its pistils, fertilizing the flower. 

On the second and third blooming days only the male parts of the flower are active. The flower will be fully open with its yellow pollen-bearing stamens developed. Pollen attracts insects and provides their reward on these days. Those insects will visit other waterlilies, some of which will be on the first day of their three-day cycle.

The plant’s strategy of producing pollen only on the second two days of blooming when its flower is not receptive to pollen prevents self-fertilization.

Several species of beetles and solitary bees use both the nectar and pollen of White Waterlilies as a food source.  When White Waterlilies close in the afternoon, insects are sometimes trapped in the closing flower. On the first and second day, they may be held overnight and will emerge covered in pollen the next morning when the flower opens. On the third day, however, when the flower petals close, they will never reopen. The stem connecting them to the rhizome mat will begin to coil and retract, pulling the flower underwater and drowning any entrained insects.  The fertilized ovules will develop into seeds that will separate and float off to establish another plant.

Birds use White Waterlilies too. Its seeds and rhizomes are an important food for ducks and Sandhill Cranes. It seems to be especially important for Purple Gallinules, providing a platform from which they hunt for floating seeds and for insects living on and under the lily pads.

The salt water surge from Hurricane Michael eliminated most of the White Waterlilies from Headquarters Pond. As a result, Purple Gallinules, which were once common there, are scarce now, but in time, White Waterlilies will recover and Purple Gallinules will return.

There’s more to birding than just birds. Come down to St. Marks. There’s a lot to observe.