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ANATOMY OF A ROSE -- EXPLORING THE SECRET LIFE OF FLOWERS |
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SIX: In the Heat of the Night ONCE UPON A TIME IN LOS ANGELES, California, a man and a woman met in a public garden with a large display of flowering philodendrons. The glossy green Philodendron selloum is a well-known houseplant. But potted philodendrons rarely produce a flower. These outdoor philodendrons rose up in full bloom. The man and woman were struck by the same observation. "It's very.... " the woman said. "Yes," the man agreed. The creamy white flower of P. selloum is a rod about nine to twelve inches long, an inch or so in diameter, shaped like a penis. The flower is really an inflorescence with hundreds of white florets, each about the size of an uncooked rice grain, growing on a common stalk, or spadix. The spadix has three kinds of tightly clustered flowers: fertile female flowers at the bottom, infertile male flowers in the middle, and fertile male flowers at the top. The spadix is cupped and enveloped by a longer leaflike bract, or spathe, green on the outside, with a light yellow interior. The man and woman began a conversation that lasted the rest of their lives. It included a house and furniture and two children. One day the man died unexpectedly. For many years, the woman lived alone. When she was much older, she found herself walking through a neighborhood in Brazil, the native home of the philodendron. Twilight darkened the air, which was scented with a faint, unfamiliar perfume. The temperature was 50 degrees Fahrenheit, and the woman had draped a light sweater about her shoulders. In front of another public garden, she stopped before a bed of flowering P. selloum. Their green spathes were loose, pulled away from the spadix. The woman bent down and touched a clublike rod. It was hot! She pulled back in surprise. She reached down again before sitting like a child, cross-legged on the sidewalk, in front of the flowers. The white spadix burned 115 degrees. The male florets generated heat. The heat vaporized a spicy, resinous smell. Suddenly, on the sidewalk, the woman heard her husband whisper in her ear. She felt him touch her neck in the old way. Everything that had ever happened in her life was still happening now.
Philodendron selloum WE HAVE LONG associated flowers with love. The Greeks turned lovers into flowers. A beautiful youth was coveted by Zephyr, the god of the west wind, and Apollo, the sun god. Zephyr killed the boy, but Apollo transformed him into a hyacinth. Another young man became a narcissus. The anemone was once the hunter Adonis, adored by Aphrodite and killed by a wild boar. Aphrodite is the goddess of love; the rose, her flower. Today we give flowers on holidays, birthdays, graduations, weddings, anniversaries, and funerals. The subtext is always the same: I love you. Are flowers a physical form of love? It's a testable theory. Put aside your preconceptions. Imagine yourself fresh, new in the world. You are walking through a forest. You see a yellow columbine or a perfect white lily. What do you feel? In Brazil, Philodendron selloum produces flowers from the beginning of November to the middle of December, when the nights are chilly and one needs a light sweater. In the city of Botucatu, botanists have observed the inflorescence as it begins to heat up around dusk. The temperature of the spadix and the flower's odor peak between seven and ten o'clock at night. At that time, too, dark beetles arrive, coming up from the soil or emerging from other philodendron flowers. The beetles follow the scent, zigzagging through the air until they come close enough for a visual cue. Then they fly directly into the spathe, crash, and fall to the bottom of the floral chamber, where the female flowers excrete a sticky, edible substance. In this safe, warm, dark place, the beetles crawl and feed and mate. As many as two hundred insects can fill a spathe, like ice cream in a cone. After this period, the flower drops its temperature but still stays warmer than the cool night air. The female florets are becoming well pollinated by those insects which came here from other philodendrons. On the second evening, the fertile male florets release their pollen. The beetles swarm up the spadix, feed on pollen, are covered in pollen, and flyaway to begin the cycle again. Biologists get excited about the philodendron, which not only produces heat but also thermoregulates, raising and lowering its heat production in response to the outside air. In cold weather, the plant's thermostat is set at about 99 degrees Fahrenheit. The sterile male florets increase heat production if their temperature falls below that level and decrease production if the temperature rises. In hot weather, the florets stabilize closer to 115 degrees. Warm-blooded animals thermoregulate by shivering and working their muscles. They increase their rates of breathing and blood circulation. This sends more oxygen and nutrients to the tissues, which need these things in order to generate more heat. Without heat, of course, we would die. Heat is what we carry in our blood. Heat is what we create. Heat is who we are. Philodendrons also need oxygen and nutrients for heat production. But philodendrons cannot shiver. They get oxygen by diffusion, through pores on the florets of the spadix. They get nutrients from inside the sterile male florets, where fat droplets look surprisingly like "brown fat," a specialized heat-producing tissue found in mammals. In an outside temperature of 50 degrees Fahrenheit, maintaining its temperature of 115 degrees, a Philodendron selloum creates as much thermal energy as a sleeping house cat. Roger Seymour, a zoologist who has done most of the recent research on philodendrons, likes to envision these flowers as "cats growing on stalks." Roger became interested in the philodendron when he was handed a cutting at a dinner party. He was astonished to find it warm. He felt, perhaps, that he had been given some kind of enchanted animal, a creature turned into a plant, a cat under a spell. You could say that Roger Seymour fell in love. *** PHILODENDRONS BELONG TO the arum family, a large group that includes other heat-producing plants. In one species of lords-and-ladies (Arum maculatum), the spadix has four parts enclosed by the spathe: a cluster of female flowers, a bristly zone of sterile flowers, a cluster of male flowers, and a second zone of bristles at the top. The rest of the spadix, or appendix, protrudes from the spathe and generates heat and odor in the course of an afternoon. Some biologists refer to the appendix as an osmophore, or odor carrier. The top bristles on the spadix act as a sieve, keeping out larger insects such as green bottle flies. Meanwhile, thousands of small midges are lured to the inflorescence, where they fall easily though the bristles to the bottom of the floral chamber. The chamber walls are coated in tiny droplets of oil. This slippery surface and the first zone of bristles keep the midges among the female flowers, where the insects feed on a sweet liquid. Overnight, the male flowers open and rain down a golden shower. The midges, covered with the sticky fluid, are now also covered with pollen. The bristles wilt. The midges escape, only to be lured again by the odor of another flowering arum. Again they fall through the bristles. Again they pollinate the fertile females. The voodoo lily is a tropical plant that can heat up to 27 degrees Fahrenheit above air temperature. For a few hours, on the first day of flowering, its warm appendix emits the smell of fresh feces, attracting flies and scavenger beetles. Later, inside the floral chamber, the base of the spadix heats up again for about twelve hours. The heat probably volatilizes the odor of starch-rich organs near the female florets. This sweet odor may trigger mating behavior among the insects, which stay inside the chamber until the male florets release their pollen. Different lily arum species have different smells. One arum will remind you of apples, another of urine. One attracts carrion beetles and smells vile. Roger Seymour says it smells like a dead cat. The flower of the skunk cabbage, also in the arum family, stays between 59 and 72 degrees Fahrenheit for two weeks in February and March. Botany books often show the plant surrounded by melting snow. It's a dramatic and puzzling picture since the cabbage's pollinators -- beetles and flies -- are not active this early in spring. The heat mechanism may be an evolutionary holdover, a habit passed down from skunk cabbage ancestors. Or, the mystery may simply require more botanists, sitting around in the snow, watching and waiting, in love with the skunk cabbage. Thermoregulation in plants is not confined to a single family. It evolved separately in the sacred lotus, which can be 40 degrees Fahrenheit hotter than ambient air temperature. The Egyptians believed that the sacred lotus was the first living thing to appear on earth. When its petals unfurled, the Supreme God was revealed. The inflorescences of some palms and the male cones of cycads (ferny plants that resemble palms) also produce a weak heat. Roger Seymour, for one, is tremendously impressed. ''The philodendron," he says, "produces more heat than a flying bird! It regulates its temperature with greater precision than some mammals!" A sense of wonder is not only our starting point. It can also be our destination. *** WHAT DOES A FLOWER have to do with love? The ancient Greeks thought there was a connection. They made up stories which we read today. The woman in Brazil, sitting on the sidewalk, thinks there is a connection. She counts herself lucky: her love made tangible, the flower burning, its desire hot.
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