The Seven Mysteries of Life

by Guy Murchie

  More commonly, I am glad to say, the animals and plants make "love" to each other, using organs evidently evolved for just such a purpose. Indeed all flowers and blossoms, apparently without exception, are reproductive organs! Something like 10,000 species of plants actually manage to get themselves pollinated by insects, most commonly by bees and butterflies, who, in terms of the business world, correspond to middlemen merchants shipping high priority goods from anther to stigma with commissions collectible at both ends. And research into this animal-vegetable commerce has shown, interestingly, that it could hardly have been initiated by either kingdom alone, but rather must have evolved symbiotically through gradual adaptive changes by both parties, the basic deal being a direct barter of food for fertilization that, during tens of millions of years, has developed countless specializations and elaborations, not only to guarantee the exchange but also to exclude outsiders from fooling around, cutting in or hijacking any particular channel of traffic. Thus flowers are shaped to accommodate a certain class or family of animals, deep bell-shaped ones welcome those with long beaks or proboscises, curved or oddshaped ones take animals fitted especially for them ... So we hear of bumblebee flowers (blue and yellow), butterfly flowers (bright), sunbird and hummingbird flowers (mostly red). We discover moth flowers (pale), rat flowers (orange-red) and bat plants (the calabash, candle tree, areca palm ...) that are open for business only at night. We hear of the saguaro cactus that is often pollinated by doves. And blossoms that specialize in particular kinds of flies, in mosquitoes, beetles (the wild rose, pond lily, magnolia...), ants, spiders, snails, frogs, possibly fish and surely man who is domesticating and engendering new varieties of plants at an alarming rate.

  The flowers, for their part, act as if they wanted to make sure that their long-standing contracts will be honored by their cosigners, showing it both by their display of colors and perfumes that invite said pollinators to serve them before anybody else gets there and by advertising themselves with all sorts of floral scripts in the form of dots, lines, arrows and other labels that identify them as specific species and pointedly guide unfamiliar visitors to the right spot to tank up. Expediting the efficient loading and unloading of the pollen to a degree that is virtually foolproof, many flowers have stamens and stigmas hinged in such a way that when any intruding insect pushes hungrily toward the nectar, he forces the male flowers to dab sticky pollen on his back and the female ones to lift it gently off again by adhesion.

  Most flowers seem naive enough to accept this sort of automation as sufficient, but an insidious minority of them, presumably after eons of bitter frustration from perpetually uncontrolled bees in their bonnets, have resorted to sterner and more fail-safe methods of making the bugs stop bugging them, and really keeping their part of the bargain. They actually have evolved traps baited with osmophores effusing scents that have shown themselves to be "irresistible" to certain passing insects, perfumes with unfloral aromas ranging from cidery to uric to fecal to musky, which lure the susceptible creatures into a type of funnel-mouthed blossom botanists call "the caldron," where they are literally overpowered and imprisoned. Darwin knew that flowers were somehow able to enslave insects, but details of their subtle techniques have only recently come to light, such as the lady'sslipper's bossy way of making a bee beehave by tricking him into sliding down a slippery chute into her jail-like interior, where one-way hairs permit him no movement except toward her sticky stigma that mops the pollen (from other flowers) off his back for cross-fertilization on his way out a special exit. And apparently the shimmering of tiny hairs around the rim of many cup-shaped flowers looks to flies like the fluttering of wings beckoning them to join a feast for that very cup (or funnel) is a favorite landing place even though coated with a substance that neutralizes the suction pads on their feet so that they slip, despite their desperate struggles, steadily and inexorably down into the caldron's pit.

  Once an insect has thus been taken into custody in a blossom brig, the flower warden wastes no time in exacting his due in pollination, the hundreds of different species of rapacious plants wielding an impressive arsenal of more ingenious than scrupulous means to achieve their vital ends. Indeed some of the loveliest blossoms are really deadly dungeons from which there is no hope of reprieve, a few of them ruthlessly digesting their prisoners in a matter of hours. Certain subdolous lilies offer both of these fates, presumably on a semisporting basis to reconcile the harsh contradictions of sex. Thus we find the jack-in-the-pulpit, whose male jail accommodatingly flings open a hatch to parole the mosquito convict freshly powdered with pollen, yet, if the flushed mosquito is gullible enough then to let himself be enticed by pungent perfume into the identical-looking female quarters of the same flower, he learns too late that Jill is a grimmer jailer than Jack and quite capable, thank you, of relieving him not only of his pollen but of his life.

  That a few plants may be evolving animal-like sexual behavior is suggested by the male members of certain ones like the barberry whose stamens erect themselves when stimulated by touching or stroking, almost as if they were penises. Sensitive plants like the mimosa (page 368) even have a motor organ, the pulvinus, that stiffens them when its cells become gorged with a fluid corresponding to blood. In a few cases all a flower's stamens will rise to the occasion together when excited by the bustling arrival of a bee, thus ensuring that the animal will be smeared with their pollen for transport to the female organ of another flower. This is a nice example of sex relativity too, for it shows the bee to be in effect female in relation to the male stamens, yet, a moment later, male in relation to the female stigmas it fertilizes.

  Hundreds of kinds of flowers, moreover, not content with emulating animal behavior in their interkingdom dealings, actually have evolved their whole outer forms in candid imitation of animals. This is particularly true of the orchid, which is now widely recognized as zoomorphic because of its resemblance to spiders, wasps, birds and other animals with a hundred disguises enshrined in such common names as adder's tongue, tenderwort, marbled crane fly, green fly and butterfly orchids, some of whom hold sway over their animal namesakes not only by looking like them but by smelling like them, provoking their belligerence as "rivals" and, in some amazing cases, even mating with them! The genus Ophrys is an orchid famous for this interkingdom "marriage," which evolved perhaps thirty million years ago in a strange symbiosis with solitary male bees of the genus Andrena. The exotic flower masquerades as a voluptuous female Andrena during the weeks just before the real female Andrena has matured, enhancing the illusion by exuding a balmy bee perfume, which, in combination, exerts such a seductive allure that the male bee seems utterly bewitched by his blooming "maiden" and, before he knows it, falls head over heels in love - or at least into such a state of infatuation that he impetuously descends to embrace and deflower her - and has repeatedly been observed actually copulating with her (insofar as that is possible with a vegetable). This is far from a unique phenomenon, for it has spread to other orchids and to flies and wasps, and somehow must have proved its evolutionary survival value for these insects over the long intervening period, not to mention its absolute indispensability to the orchids, each of which in effect is thus "impregnated" through the inadvertent cross-fertilization performed by its enraptured mate!

  Some flowers, believe it or not, literally get "in heat" in order to achieve procreation - even more so than do animals - and the large, lush voodoo lily, which grows in the tropics and is pollinated by flies and scavenger beetles, generates such rapid metabolism when respiring its reek of carrion and dung to lure them that the temperature of its reproductive organ, called the spadix, rises near its tip as much as 270 F. in a couple of hours. Another lily, Cryptocoryne ciliata, which takes root on the bottoms of ponds and streams, raises a "flag" above the surface that exhales such hot, pungent breath that insects are drawn to it and cannot resist landing and crawling all the way down into its foot-long submarine chamber, where the flower sees that they remain until they have paid
the expected forfeit in full.

  Among the countless interkingdom cause-and-effect relationships are what ecologists call positive and negative feedback between such cyclical factors as the warmth and coolness of days and nights and the pace of swarming ants, the pitch of chirping crickets and the bustle of human crowds. Did you know that the number of bees born each summer day is precisely regulated by the number of flowers that blossom in the nearby countryside? That forests humidify the sky for miles above them, sometimes saturating it enough to form rain clouds capable of returning a vital mist even in the dry seasons? That stag antlers are known to the French as bois de cerf because they represent plant life in an animal and are sometimes more asymmetric than trees, the comparison being substantiated by modern biological investigation into antlers' meristems, abscission zones and the similar ways in which hormones control the growth in both kingdoms? That hydrodictyon cells colonizing one of the tiny round vesicles in your body mysteriously crowd together in one dimension while spreading apart in the others, with the curious result that they form not a ball but a disk shaped like the assemblage of stars of the Milky Way?

  The field of geology has always been full of its own special interkingdom relationships, many of them known to modern prospectors who have taken to making chemical tests of plants to find out what sort of metal traces their roots have absorbed out of the ground. If you are looking for gold, for instance, it would behoove you to note where horsetails grow because these ancient plants have a fondness for it, and one botanist recently reported a case of horsetails absorbing gold in the proportion of four ounces per ton of plant material. And a kind of mold was recently discovered in Russia that can extract up to 98 percent of gold in liquid solution. Wild buckwheat, native to the western United States, has a similar affinity for silver and is known to be abundant near silver mines. Likewise the wild poppy and the dandelion are clues to copper in the American Southwest, locoweed often marks uranium deposits there and tumbleweed and milk vetch are the tip-off for selenium.

  Animals share in this attraction for minerals too, because all protein molecules seem to welcome a few metallic atoms in their complex spiral latticeworks. Australian sheep have been known to die for lack of a tiny amount of cobalt in the soil, and other animals have succumbed because they needed a tiny trace of copper or manganese. The latter metal in fact is so vital to ants that miners in the mountains of New Mexico have been reported to use anthills to plot the courses of manganese veins. What we call organic molecules, it seems, almost certainly evolved out of simpler inorganic ones, so the swapping around of atoms is presumably a basic characteristic of all matter, dead and alive. Which may well be why life has gotten so involved with metals, metallic atoms being the most swappable because of their footloose outer electrons, which, having few ties, tend to be chemically venturesome - venturesome in this context meaning not merely flirtatious but actually promiscuous.

  Applying such factors to the elusive question of where are the borderlines between kingdoms, it becomes more and more obvious that none of the kingdoms has really unequivocal boundaries anywhere. Not only do a number of animals, such as the barnacle and the sponge, live passively like vegetables, spending their adult lives rooted in one spot, but many vegetables are as active as animals, even mobile (page 55) and, in numerous cases, carnivorous to the extent of catching and eating insects. I am told there are a good 450 known species of meat-eating plants from microscopic worm-snaring fungi (page 97) to the jack-in-the-pulpit and foot-deep leafy urns in Borneo which often capture amphibians and"reptiles. The Venus's-flytrap, best known of these predators, has animal-like senses in the form of three hairs on each half leaf which enable it to distinguish between a living and a dead object. In fact its ingeniously spiked trap does not close unless at least two hairs are touched in succession or the same hair twice within a few seconds. Even more extraordinary as an animal's pitfall is the beautiful water weed called bladderwort, whose submerged threadlike stems grow dozens of bladders with trap doors that snap open when a swimming insect touches their sensory hairs, letting the water rush in, sweeping the insect with it, whereupon the door closes again and the plant promptly pumps out the water to be ready for the next victim.

  Some pitcher plants, which normally trap flies and moths, are so large they have been observed and photographed catching mice, digesting them in their usual period of about ten days, after which they spit out the bones and reset themselves. There are also the sundews and butterworts that work on the flypaper principle, the latter exuding a sticky mucilage whenever an insect alights on a leaf, followed by acid with a digestive enzyme that quickly paralyzes the victim while the edges of the leaf gradually curl up and wrap it in a tight roll for thorough digestion. It is significant that the "stomachs" of all these preying plants secrete virtually the same juices as animal stomachs, although the plants are inevitably not only slower but gastronomically much less durable than the animals, rarely managing to tuck away more than three meals (per stomach) in their lifetimes.

  Perhaps closer to being an animal is the sensitive mimosa plant, native in warm countries like India (where it is called "coy maiden" because of its shyness), which has contractile hydraulic tissues (pulvini) similar to muscles at the junction of leaf and stem and a nervelike control system that includes something comparable to a reflex arc. These animal-like developments enable it to dodge a browsing cow by furling and withdrawing its frond from a wide open to a closed position in what Sir J. C. Bose measured as less than a tenth of a second after the first touch, with rapid successive closings of other fronds down the length of the branch. This startling responsiveness of a mere vegetable is not as fast as that of a frog, who reacts to a touch or a mild shock in about a hundredth of a second, but it compares well with that of a turtle and is much faster than that of a snail. This mimosa is animal-like too in the way it gets tired, for it normally takes about twelve minutes to recover from furling its leaves, but, if touched several times in succession, responds more slowly both in closing and reopening and, if driven by repeated blows (as in a hailstorm) to complete exhaustion, it may become too paralyzed to respond at all. However, after half an hour or more of rest, it will usually recuperate and return to normal.

  Being acutely sensitive to temperature, light and radiation as well as touch, this plant's capability naturally varies with the weather, and tests show it to be most active at 91°F. in sunshine, becoming a bit sluggish when clouds cover the sky, literally turning numb with cold at 50°F. and suffering a kind of heat stroke at about 150°F. Like a cat that purrs when fondled but flees from a kick, the sensitive mimosa turns its leaves toward the friendly sun but pulls them cringingly away from any light much brighter. Besides being a lot more sensitive than man to light and (some botanists think) to radio waves, plants in general are known to feel very faint electric currents, one called biophytum responding to a shock only one sixth as strong as can be detected by a human. The nervelike impulse in the average plant has been measured to travel about an inch a second, but in some mimosas it has been clocked at 18 inches a second. As in animals the impulse can move in either direction but "prefers" one direction and will go faster and easier that way. Also as in animals, there are both sensory and motor nerve impulses in plants, according to Bose, the motor impulses traveling generally faster by six times.

  The idea that plants can become dissipated is by no means just an anthropomorphism, for Bose and more recent experimenters have offered them alcoholic drinks and repeatedly succeeded in getting them drunk. When Professor Wilder D. Bancroft gave a sensitive mimosa a drink in his laboratory at Cornell, presumably submerging its roots, its initial reaction was a kind of glow of confidence, as from one's first cocktail. The little plant held its leaves straighter, closed and opened them faster and looked positively eager to perform. The stimulus had given it a mood that one observer described as "cocky." After the next drink, however, it began to lose control. Its movements turned haphazard like those of a sot with wobbly knees unti
l only its stiff lower stem held it from staggering. Next it grew dopey and its leaves folded and dropped and it figuratively slid "under the table." But after a quiet four hours of "sleeping it off" it "opened one eye" in effect, then, despite its "hangover," placidly climbed back "on deck" as if nothing had happened.

  Perhaps most suggestive (not to mention controversial) of all Bose's findings of animal-like traits in plants is his assessment of their specific, if not individual, sensibilities. Thus he not only particularized the pea as suffering an actual death agony in the pot, but found the undemonstrative carrot one of the most excitable and nervous of all vegetables, concealing feelings even keener than those of the sensitive mimosa. Celery, on the contrary, he rated as low-strung, tiring easily and caring little whether it be eaten or left to rot.

  Although few biologists anywhere seem to have accepted such interpretations as justified, at least they have served to make us aware of the distinct possibility that to some degree a tree, any tree, is capable of feeling the woodsman's ax. And, beyond that awareness, a new and different sort of insight into vegetable senses may come from a look at a branch of life where the genetic union between vegetables and animals is most obvious: that of plankton in the sea. The sea of course is where life has done most of its evolving from the vegetable into the animal during the last billion years, a process believed to be still going on, particularly among the swimming flagellates, which are continually diversifying into myriads of very dissimilar varieties with anything from one to scores of ciliated propellers. As you may have suspected, both botanists and zoologists study these creatures for the reason that they behave like vegetables and animals at the same time, some of them (such as the flagellate Euglena) actually glean the advantages of the two kingdoms simultaneously, using green chlorophyll to get energy from sunlight by photosynthesis like a tree, while spending that same energy to pursue and capture their prey like a cat, then eating it for more energy with which to grow more chlorophyll, etc.