Strangers in the Night

THEY'RE LIGHTING UP THE NIGHT

I sat in the gathering dark, as the thorny shapes all about me melted into shadow and then into a seamless, star-speckled night. My eyes slowly dilated, a poor imitation of the giant eyes of an owl. I strained to separate the small sounds of the night, a pitiful parody of the ultrasensitive ears of a pack rat. I strained to separate living shapes in the dark, lacking the infrared sensors of a rattlesnake. We humans are strangers to the night, blind travelers without passports in an alien world. But on this one night, I sat awhile in hope of brushing against the boundaries of that other world. Dimly I heard a rustle off in the bushes. Somewhere in the distance, I heard the lovelorn croak of some small damp creature. Cicadas started a serenade, no doubt drawing the attention of both would-be suitors and other creatures with a less amorous taste for cicadas.

AT THE DESERT BOTANICAL GARDEN

THEY'RE LIGHTING UP THE NIGHT

It's not easy to see the desert in the dark. And for years that frustrated the folks at the Desert Botanical Garden in Phoenix. But no longer.

Last summer the Garden opened a portal into this parallel universe with artfully placed, dimly glowing lights scattered among its 20,000 plants, representing 4,000 species on 145 acres in the middle of Papago Park. Brand-new, softly illuminated trails wander among desert plants drawn from across the planet, discreet spotlights accent rare crested saguaros, seldom seen night-blooming flowers dangle their scented lures for bats and moths, and bemused visitors wander through a landscape softened and soothed by the darkness. The lights have drawn some 50 people nightly into Nature's alluring swing shift.

The lighting project, funded with a $160,500 grant from Scottsdale's Hospitality Commission, has added a new twist to the Garden's decades-long effort to explain and conserve the remarkable variety of desert plants. The night lights supplement other new daylight additions, including an energyand water-efficient home, which houses a family whose every kilowatt and toilet flush will be monitored in the name of conservation research. These educational programs help pay for ongoing conservation projects.

The Garden, which has a staff of 50 and a budget of about $2.2 million annually, maintains a room full of giant refrigerators and freezers harboring seeds and samples of thousands of plants, including 35 threatened and endangered species.But right now, it's the lights that have desert lovers excited.

"This has been on our drawing boards for a long time," said Mary Irish, the Garden's director of public horticulture. "So much happens in the desert at night, and people never get to see it."

The nighttime tour of the Garden provides a unique opportunity to glimpse the nocturnal desert ecosystem in which bats, frogs, moths, scorpions, snakes, kangaroo rats, and an array of darkadapted plants form intricate, life-sustaining connections.

It all starts with the plants because the whole ecological edifice rests on their conversion of sunlight into living tissue.

"Plants are the initial start of the food chain," said Liz Slauson, curator of the plant collection. "Once you remove a plant, you may affect the pollinator, the microorganisms in the soil, the seed harvesters, the browsers, and all of their predators."

That's why the whole desert ecosystem depends on how Sonoran Desert plants solve certain thorny problems: scattered rainfall adding up to four to nine inches a year and summer ground-level temperatures that can climb above 120° F.

Each desert plant has evolved with brilliant innovations to survive such harsh conditions. The spiny ocotillo sprouts leaves when it rains and becomes a seemingly dead stick when times are hard. The paloverde turns its leaves into threads, puts out a vast network of roots, and conducts photosynthesis in the green cells of its green trunk. Saguaros send out a shallow network of roots sometimes twice their height, sopping up rare rains and storing the water in their massive trunks. Hedgehog cacti also store water in their fleshy tissue, which they shade and protect with leaves that have evolved into a mat of sharp spines. Creosote bushes act as nurse plants to many small cacti, their seemingly indestructible waxy leaves providing excellent shade for the young succulents. Desert grasses and wildflowers scatter seeds that lie hidden in the soil for years, awaiting just the right combination of rain and temperature.

Over time, desert conditions have created a special relationship between desert plants that bloom at night and nocturnal animals. Many desert plants bloom in the hottest, driest part of the year and open their flowers at night. Fortunately the long interaction between plants and animals has provided a rich variety of hungry nighttime pollinators. Nature's intricate push and pull of evolution has assured a frenzy of both plant and animal activity once the sun sets in the superheated desert.

Bats remain the most haunting and noticeable of these animals, fluttering through the warm darkness like escapees from a dream. The creatures remain crucial pollinators for numerous plants, including many species of agave and, to some extent, the saguaro. They're especially important in southern Arizona, where proximity to tropical Mexico, an array of caves, and moderate temperatures have guaranteed a large number of bats. They're less important farther north where moths play a more prominent role among the nighttime pollinators, including the impressive hummingbird-size hawk moth. Some moths evolved in close harmony with the plants they pollinate. Yucca moths provide the most famous example. Many spend their entire lives from larva to winged adult inside the fruits and flowers of certain species of yucca. The moths may chemically cue the yucca to produce fruit, flowers, and nectar. They gather pollen balls, stuff those balls down the throat of the flower, then lay their eggs nearby. This gives the larva something to eat when it hatches, pollinating the plant in the process. It's such a tight relationship for many pairs that both yucca and moth would quickly become extinct without their partner. Other plants remain open-minded about dispensing their nectar, although wonderfully specific about when they produce flowers. Perhaps the most famous is the Queen of the Night, a sticklike cactus that grows inconspicuously until it stages a onenight extravaganza of huge white flowers, perfuming a single night in June with an intoxicating scent reminiscent of the gardenia. The flowers wither with first light, leaving no hint that the cactus that produced them still lives. The Garden boasts several Queen of the Night plants, and in years past their mysteriously coordinated blooming has prompted news advisories to local television stations and opening the Garden for special flashlight tours. Now the Queen of the Night and other night-blooming cacti should be regular stops along the lighted trail. "It's the most unremarkable looking plant, found at the base of some tree or shrub," Irish noted. "But it produces dozens of tubular eight-inch-long flowers."

THEY'RE LIGHTING UP THE NIGHT

Of course the cool of the desert night calls forth more than sweet flowers. An array of desert animals takes advantage of the cooler nights, especially during the long harsh summers of the Sonoran Desert. Many rodents emerge from burrows, mostly to scurry along secret trails in search of seeds. The kangaroo rat is among the most endearing and important. Researchers have discovered that it helps control the mix of desert plants and grasses by ceaselessly gathering up thousands of seeds of certain sizes and storing them in huge underground granaries. Pack rats, those renowned scavengers, also ply their trade by night, gathering up cacti, seeds, and bits of food. The night-loving rodents draw a network of predators. Snakes slither through the underbrush, using heat-sensitive pits beside their noses to detect warm bodies within striking distance. Owls patrol the skies, using two different sets of ears to triangulate and pinpoint the sounds of their prey as they swoop down on wings edged with special feathers that act as sound baffles. For human beings, one of the true stars of the night parade has to be the palm-size Woodhouse toad, which takes up position near the lights to feast on the wealth of insects drawn to the glow. "This is toad heaven," said Irish. "They'll park themselves by a light and feed for hours. I've sat eight inches away and just watched them."

Sitting in the dark, I was tempted to wander off in search of the small toad I heard croaking plaintively in the distance. But my back was nicely fitted to the cooling slab of granite against which I rested. Besides, the night had come to me, engulfing me in its whispers. Perhaps that stirring in the brush was a kangaroo rat, sculpting the seeded desert to its needs with its industrious foraging. Perhaps if I sat perfectly still for a long enough time, a stealth owl would pass overhead like the gathered wings of a long dark dream. And I still had stars to count and constellations to discover.

Peter Aleshire has long admired frogs and moths and other critters that go bump in the night. He also wrote the article about Capt. John G. Bourke and the "Event of the Month" in this issue.

When Jerry Sieve came to Arizona from Ohio in 1969, he visited the Desert Botanical Garden to become familiar with the flora of his new home state.

WHEN YOU GO

The Desert Botanical Garden is in Papago Park on Galvin Parkway in Phoenix. It is open from 8 A.M. to 8 P.M. October to April; 7 A.M. to 10 P.M. May to September; except Christmas Day. Admission is $6 for adults, $5 for seniors over 60, $1 for kids five to 12 years old, and free for those under five. For more information about attractions and special events, write Desert Botanical Garden, 1201 N. Galvin Parkway, Phoenix, AZ 85008, or call (602) 941-1225.