Working the Night Shift on the Desert...

Let's take a visit to the world-famous Arizona-Sonora Desert Museum (ASDM; a non-profit institution) just west of Tucson, AZ. in the Sonoran Desert. This unique museum and "biopark" showcases the natural history surrounding the geology, plants and animals of this rich desert region. For a test period this summer, through September 30, the ASDM will be open Saturday's until 10 pm. This is to highlight the Night Zone with a new nocturnal pollination garden and other exhibits seen at night when most of the desert's animals come out to play. So, come out after the sun goes down, have a snack and watch the critters play. Museum members get in free. For more information on the Night Zone, please call the museum at (520) 883-1380.

Better yet, why not visit the ASDM online at their new WWW site by clicking here on their unofficial mascot, the Mountain Lion.

We often forget about pollen (unless we suffer from hay fever!), the act of pollination and the many animals which work day and night to collect food for themselves and their young, and in so doing effectively pollinate crop and native plants. Pollination is simply the transfer of pollen grrains from an anther on one flower to the receptive female stigma on the same flower or a different one. It sounds like a simple act and it is. Pollination, is however, vitally important. The wind, water and various animals (bees, bats, beetles, birds, butterflies, flies, moths etc.) provide invaluable pollinator services to ecological communities around the globe. Without pollination there would be little food (in the form of vegetables, fruits, berries, some drinks) to go around. In fact, it has been stated that...

"One in every three mouthfuls of the food we eat, and the beverages we drink have all been made possible by successful pollination of plants by various animals" Gary Paul Nabhan, The Arizona-Sonora Desert Museum

Pollinators-

Pollination takes place around the clock. The night shift is worked by such animals as nectar-feeding bats and moths. Though day-active humans rarely see them, they are essential to plant reproduction. Without them we would not have such night-flowering plants as giant cacti (like the Arizona state flower, the Saguaro), papayas, kapok, tobacco, bananas and many century plants. When habitats are divided and isolated, or when pesticides are used, both plants and their pollinators are threatened.

Night Life-

Some plants bloom at night and fade the following day. They attract night-active pollinators, like bats or moths, using strategies that work well in the dark. Many have a heavy fragrance and are white or light-colored. Flowers of different species open at different seasons and times, some in late afternoon, some at dusk, and others (like the saguaro) as late as midnight. This strategy encourages pollinating animals to transfer pollen between flowers of the same species.

Caterpillars-

It may surprise you to know that moth species outnumber butterfly species 10 to 1. Because most moths are active at night, we may be more familiar with their day-active larvae. Hawkmoth caterpillars are usually large and green. They feed on a variety of plants, which are often different from those visited by their parents. The Hyles and Manduca hawkmoth caterpillars found in the Sonoran Desert feed on such common herbs as tobacco and jimsonweed (sacred Datura ).

Hawkmoths-

Watch in your garden or by a roadside patch of sacred datura. Look at dusk for a large, aerobatic moth which hovers like a helicopter in front of a newly-opened flower, drinks, then darts away. There is a good chance this is a hawkmoth (also called a sphinx moth or hummingbird moth), a very important night-time pollinator. The proboscis (tongue) of a hawkmoth is unusually long, sometimes longer than its body. The proboscis can reach nectar hidden deeply within floral tubes, becomming dusted with sticky pollen grains in the act of probing and drinking. The moth then carries its pollen load far and wide as it continues it search for more flowers and the sweet nectar about twice as concentrated as a Coke Classic! Thus, like almost all pollinators, pollen is carried from plant to plant as the accidental byproduct of an adult insect going about its daily "shopping" routine at the floral marketplace.

*We thank the ASDM staff for allowing us to use (see above) and add to the text from four of their new illuminated signs (Created by Tucson artist Paul Mirocha) in their new Night Zone pollinators exhibit.

Something else new is happening at the Zoo........

*Desert-Alert*

A few lucky volunteers got to work with ASDM staff members this summer and study the pollination of a rare Night-Blooming cactus.

Desert-Alert is an Earthwatch-style program for public participation in desert research and conservation monitoring. It aims to involve the public, especially amateur naturalists, in ongoing pollination projects which will help them gain an understanding of how scientific research is done and what is practical applications may be. Volunteers work alongside mentors in the field and lab to understand the private lives of desert plants. For further information on this exciting program please contact Mrill Ingram, the Desert-Alert program coordinator at (520) 883-3006.

Desert-Alert 1995: What Happened?

This year the group, under the direction of Science Advisor Dr. Gary Paul Nabhan, tackled the monitoring of the floral biology of a rare night-blooming cereus, a cactus that goes by the scientific name of Peniocereus striatus. Its majestic 8-10 inch long blossoms open at dusk and close the next morning for just one or two nights each year! One plant near Tucson had 40 blossoms open during one night and was quite a spectacle.

These incredible blossoms have to accomplish their combined tasks of attracting fly-by-night hawkmoths with long distance sensory billboards, disperse pollen to other flowers and be pollinated themselves so as to produce fruits containing the seeds of the next generation. To accomplish this, they attract the services of giant hawkmoths as their sexual go-betweens. The flowers open very rapidly starting at dusk and are fully open about an hour later. They have hundreds of long stamens tipped with pollen-containing anthers. Hidden deeply, 8 inches below at the base of a narrow floral tube is the sweet nectar treasure, fully 25% dissolved sugars and seveal times sweeter than a soft drink. The color of the flowers is a creamy white which can be seen from quite a distance especially on moonlit nights. A perfume is also being wafted on the warm desert breezes. It signals searching hawkmoths that a floral cornucopia awaits them nearby. The giant moths fly upwind in search of the Peniocereus flowers. Once there, they hover in front of them without alighting and insert their long tongues and greedily drink the nectar. Pollen grains stick to their tongues and get rubbed off thus pollinated flowers visited by them later that night. By next morning, the sun hitting the flowers causes them to shrivel up and fade away, their brief sexual escapades not to be repeated until the same time the following year.

Join us now for a brief photo late night tour at one of the Tucson Desert-Alert sites with photographer and participant, Steve Buchmann.

In this photograph, the sun is just about to set over the rugged Tucson Mountains. A night-blooming Peniocerus striatus plant offers up a candelabra-like array of giant buds which are rapidly opening toward the desert night sky. They beckon the moths to feed.

Here we see a group of 3 flowers right after they have fully opened. No hawkmoths have yet visited them. No pollen or nectar has been removed from them. They are waiting for their moth guests to arrive at the fragrant white banquet tables.

A closeup of one Peniocerus blossom showing the hundreds of stamens (the combined anther + filament) containing the particle like pollen grains and the starlike arrrangement of petals and sepals. Up through the center of the flower is the pistil tipped with the receptive female portion known as the stigma. This is where the pollen grains must be rubbed off by visiting moths. If that happens, then by tomorrow pollen tubes from the pollen grains will be travelling down the style to fertilize the ovules within the ovary below. Without such pollination and subsequent fertilization, the unpollinated flower would wither and drop off without producing a fruit.