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NATURE HAPPENINGS - April 2007

The Moonlight Garden
by Damian Fagan

The flowers that keep
Their odor to themselves all day,
But when the sunlight dies away,
Let the delicious secret out
To every breeze that roams about.
--Anonymous

After dark wildflower watching is not a major spectator event in Moab. But, for those that do venture out at night, there are “delicious secrets” to discover.

Flowers that open at night attract moths, beetles or wasps (sometimes bats) depending upon the size of the flower. Other pollinators take advantage of these flowers that open in the late afternoon or are still blooming in the morning hours. These are opportunists, not the regular crowd.

Many, but certainly not all, night-blooming flowers are white. The flowers release scents onto the night air that lure in the pollinators.

Of these night-bloomers, most bear flowers with deep corolla tubes. This design provides that moths, with their long tongues, can reach the nectar rewards at the tube’s base. Some plants like the yuccas do not have a tubular corolla, but they have a nyctinastic tendency – meaning the flowers move about at night to ease the entry for visiting moths.

During the day, yucca flowers hang downwards with the petals “close-lipped.” At night, the flowers turn upward and the petals open slightly. The flowers also release a sweet, soapy scent that helps to attract the yucca or pronuba moth – the specific pollinator.

The relationship between the yucca and the moth is mutually beneficial to both plant and insect. The female moth visits a flower and rolls a small ball of pollen that she carries to another plant. As she stuffs the pollen mass into the flower’s stigma (pollen receptor), she also deposits fertilized eggs into the plant’s ovary. The act of pollination assures that her developing larvae will be able to feed on the maturing seeds.

With a flashlight and some rearranging of the yucca’s petals, you can easily watch this event unfold. The ½” long moths crawl all over the flowers and seem out of place under the canopy of petals.

If you have great patience, another nocturnal wildflower event to watch is the floral opening of dwarf evening primroses. These low growing plants occur throughout the desert, sometimes in great abundance. When mature, the pressure from the swelling petals forces the protective sepals to burst apart and curve backwards. The ghostly white petals, connected at the tip by a tiny spur, start to unfurl and break this clasp. The process takes about 30 minutes, but is one desert spectacle rarely viewed.

The evening primrose flowers attract white-lined sphinx moths – large moths that are often mistaken for hummingbirds because of their size and flying abilities. These moths uncurl their long tongues to reach the nectar rewards deep within the flower’s trumpet-shaped corolla. In the process, pollen rubs off on the foreheads and is transferred to other flowers by these large moths.

By evening’s end, the opened flower will fade from white to pink. This signals the end of this flower’s one-day reign.
There are numerous other flowers that are also worth watching in the evening. There are sacred daturas, showy four-o’clocks with their beautiful magenta flowers, blazing stars, lizard-tail guaras, and sand verbenas to name a few. The verbenas have snowball-like clusters of flowers that unleash a very sweet aroma. The flowers attract moths at night, although butterflies take advantage of open flowers in the late afternoon or early morning.

So as the sun sets, don’t give up on the desert flowers. Some of the best blooming is still to happen in the moonlight garden.

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