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A Slow-Motion Riot of Evolutionary Competition and Adaptation


By Lawrence Biemiller

Storrs, Conn. -- Somewhere water is dripping and fans are whirring. The air is warm and humid, thick with scent. Leaves and fronds of every size and shape crowd narrow passageways, brushing against your shoulders as you pass, describing complex curves above your head. Here and there the stillness of delicate flowers seems almost to stop time -- angel's trumpets, calla lilies, a pale purple orchid called Phalaenopsis schilleriana. You could lose yourself in the University of Connecticut's greenhouse for hours.

But even if you stayed all day, you might easily miss the real story here, because it's happening at the edges of our frame of temporal reference. To a casual visitor, the greenhouse seems a peaceable kingdom under glass, a place of beauty and delight. Because we look so quickly, though, we don't see what's really going on -- a vast, slow-motion riot of evolutionary competition and adaptation. Only if we make an effort to think in terms of millennia do we begin to understand what we see here: That orchids, dissatisfied with their lot on the rain-forest floor, somehow leaped into the branches of trees and started new lives in which their roots never touch soil. That some tarted up their flowers to look like female insects, then deposited pollen on the backs of males attempting copulation (being males, they never learn -- and so carry the first orchid's pollen to the next, and the next, and the next). That bog plants, desperate for nitrogen, taught themselves to trap and digest insects -- and some, like the Venus flytrap, built hydraulic machinery to make the trapping easier. Hydnophytum welcomed into its roots colonies of ants that, in turn, protect it from predators. Oxalis even learned to throw -- it "forcibly ejects its seeds 8 to 10 feet," says Clinton Morse, the greenhouse manager, who knows Oxalis all too well. Its throwing arm has made it the greenhouse's most troublesome weed.

In almost every branch and stamen, in fact, you can discover some solicitation, strategy, or feint, whether it be a rain-forest come-on of the most licentious sort or a desert get-rich-quick scheme. A tour of the greenhouse is a crash course in evolution, a four-color walk through the pages of the Origin of Species -- at least it is if you have a guide like Mr. Morse.

In the first room, he points out Amorphophallus, notable for having one of the world's largest inflorescences. The plant, which is found in Sumatra and can grow to a height of 15 feet, produces a spiked flower structure eight feet tall that lasts only 30 hours before collapsing. "It's about 20 degrees warmer than the ambient air temperature, and it reeks," says Mr. Morse. "Like a men's room that's not cleaned for a week." But the scent is perfect for attracting flies, which the Amorphophallus relies on for pollination.

The next room is much larger. Palm trees and giant ferns grow side by side, the fronds of the tallest palms bending up against the glass roof. "This plant is cocoa," he says, pointing to a modest tree with tiny flowers growing directly out of its branches. "We have a small collection of palms -- this is a date palm. And this is a new banana plant. A banana is not actually a tree -- it's an herb. The stem will produce a cluster and then die back."

The greenhouse has about 10,000 square feet of space, Mr. Morse says, and contains about 3,500 species. "Most plants there are two of, in case one buys the farm or gets loaned to a department and comes back crispy." He maintains a World-Wide Web site that lists everything in the greenhouse's collection (http://florawww.eeb.uconn.edu). Researchers and other greenhouse managers can check the site and "ask for leaf material or seeds," he says, and sometimes he can barter with them for plants his collection lacks. "I have zero budget for acquisitions, but I can trade with other institutions, or with private individuals."

Some of the plants take more space than others, of course -- the collection includes a species of Wolffia that is "the smallest known flowering plant." Each plant is nothing more than a speck of green floating on water in an old fish tank. "The leaf blade splits open and the floral structure sticks out," Mr. Morse says. And some plants are more demanding than others. Many of the cacti need water only once a week, but most of the other plants get watered at least once a day -- sometimes two or three times, if the day is sunny and the air is dry. Watering "takes 5 1/2 hours on a sunny day, if you don't dawdle," he says. "Cloudy days you still have to check everything." Mr. Morse has one full-time assistant, and a number of students work part-time.

Pest control is another problem. The greenhouse dates to the 1950s and is far from airtight, so it cannot be fumigated. Instead, pesticides must be sprayed on one plant at a time, by someone in what Mr. Morse refers to as a "space suit." If he ever has the budget for it, he would like to try natural alternatives, such as releasing "predatory or parasitic beneficials," so that he would "eventually get a balanced ecosystem." In the meantime, he tries to keep gnats and slugs under control, and to keep pollinators from making unauthorized visits to plants that are part of faculty members' research. In addition to some 30 researchers, the greenhouse serves more than 50 university courses and accommodates all sorts of visitors, from grade-school classes to university staff members on their lunch breaks.

When they've finished watering and weeding, Mr. Morse and his staff keep busy pruning, repotting, and sometimes doing a little hand-pollinating, if necessary. And there's always more to learn. "People will collect stuff in foreign countries, and there's no documentation on how to grow it, so you're guessing," he says. "We lose our fair share of plants."

One of the more interesting plants from a foreign country is a Dendroseris litoralis, an unusual, tree-sized member of the lettuce family that evolved in the Juan Fernandez Islands, 400 miles west of Chile. According to Gregory Anderson, head of the university's ecology and evolutionary-biology department, the plant had become almost extinct -- only three specimens were known. It is now being propagated in greenhouses around the world, as well as on the two islands themselves. The islands have no bees, flies, or butterflies -- Dendroseris flowers are pollinated by hummingbirds. And if no hummingbird comes along, Mr. Anderson says, the flower's female parts keep growing until they double back and touch the male parts.

So many plants, so many strategies! Welwitschia is a rare, primitive plant that grows only two leaves, which get longer and longer until the ends brown and break off. "It's one of those you don't see too often," says Mr. Morse. Salvina molesta, an aquatic fern, is kept sequestered, lest it escape into Connecticut's waterways and become a major nuisance. Neobeckia aquatica -- the North American lake cress -- is increasingly rare as development overtakes its habitats. Hadrodemas has a root parasite, an unidentified Orobanche, that once a year "puts up a little flower -- that's all you ever see of it," Mr. Morse says. "The rest of its life cycle is spent living on the roots of its host." You get caught up wondering why -- what benefit does Ruscus get from growing its flowers right out of the middle of its leaves? ("Kind of a funky adaptation," Mr. Morse says.) What encouraged the orchid called Lockhartia to weave its leaves together as they grow, producing a long, elegant fan with a tiny flower at the tip? How did orchids get up in treetops, anyway?

Once you start, you can't stop. The flower parts of figs are inside the fruit, Mr. Morse says -- minute gall wasps crawl in through one end and do the honors. How did a fig think that up? How did wasps and ants and bees and hummingbirds get so cozy with plants anyhow? And what can we learn about ourselves from the way plants behave? An orchid may not have what we think of as consciousness, but its evolutionary achievements seem to betray something remarkably similar. You leave the greenhouse with more questions than you could answer in a month, probably a lifetime. But just to ask them -- to know that they're waiting for answers, along with at least two more for every plant you passed -- to have your curiosity thus piqued, is in its own way every bit as refreshing as seeing spring's first crocus.

Copyright © 1996 by The Chronicle of Higher Education. Published April 5, 1996.