Naturalists are, literally, coming on like gangbusters. From anthropologists to zoologists, they are increasingly helping law enforcement officers solve crimes by gleaning tips from an odd snitch: Mother Nature.

The telltale clue can be a fireweed leaf stuck to a rapist's trousers or a greenbottle fly egg in a murdered man's ear. The naturalists may lack Sherlock's calabash or Columbo's rumpled trenchcoat, but they know their flora and fauna.

As Walter Rowe, professor of forensic sciences at George Washington University in Washington, D.C., puts it: "To resolve cases today, police rely greatly on physical evidence." Those clues, he says, often come from the natural world, and only naturalists can analyze them. Insect larvae on a corpse can fix the time of a murder--if the sleuth is an entomologist. From bits of bone, anthropologists can deduce the victim's gender, age, health and, often, the cause of death.

For these scientist gumshoes, it all comes naturally. Here are four cases showing how they make the pinch.

The Case of the Poisoned Pen Letter

In April 1986, an Army colonel arrived at the Beltsville, Maryland, office of Charles Gunn, a U.S. Department of Agriculture botanist. The colonel handed Gunn a packet of seeds.

The colonel explained that an American soldier stationed in the United States had received the seeds in the mail from England. No one in the Army could tell what they were. He asked Gunn--one of the world's top seed experts--to try to identify them. Then the colonel left.

Gunn cut open one seed. It had no enclosing ovary, he saw, and so it was a gymnosperm--an evergreen seed. "That narrowed down the field considerably," says Gunn, explaining that 90 percent of the world's identified plants are angiosperms--species such as orchids and oaks, with seeds in an enclosed ovary.

"I knew I'd seen a seed like this before, and I knew there were only 14 families it could be from," says Gunn, whose seed knowledge is encyclopedic. "That was a huge step forward."

Downstairs, Gunn went to work in the U.S. National Seed Herbarium, of which he is curator. During his 25 years with the Agriculture Department, he has made the herbarium one of the world's top seed collections, with an unrivaled library of books, drawings and photographs. He pulled out the gymnosperm file drawer and began searching for a matching seed. The seeds the colonel had given him were tiny and dark brown--"Nondescript," says Gunn. But he had guessed their species, and the file confirmed it: They were from the yew family.

"I thought to myself, 'This is not good, not good at all,'" says the researcher. "Most yew seeds are extremely poisonous."

Yew species are few. Quickly scanning his seed collection, Gunn found one that exactly matched the seeds he had received from the colonel. It was from the yew species Taxus baccata.

"It is one of the most poisonous of all the trees and shrubs in England," says Gunn.

Several days later, when the colonel reappeared, Gunn told him the seeds' species and explained that they were extremely dangerous. "He was very surprised," recalls Gunn. "I think when he first brought them in he thought they were marijuana seeds."

Gunn learned that the American soldier had received the seeds in a letter from his girlfriend in England, where he had been stationed. This young woman, also serving in the American military, had suggested that her boyfriend eat the seeds.

"They apparently had a lovers' quarrel," says Gunn, in an understatement. As he puts it: "The person who mailed these seeds definitely wanted to kill someone."

The Army has kept the case quiet. And Gunn, who often consults on court cases, maintains his objectivity in investigations by learning only the details he needs to analyze evidence. But he is sure the soldier did not eat the seeds and die because the colonel had not originally asked him to determine if the seeds were poisonous.

"Also, the seeds were not treated as evidence," says Gunn. "Seeds used as evidence are sealed in a plastic bag, and I cannot remove them--I could never have cut the seed open if this was being used in a murder case."

Love was thwarted, apparently. But so was murder.

The Case of the Telltale Cocoons

During the summer of 1989, divers exploring the Muskegon River in Newaygo, Michigan, spotted a submerged car. Peering through the windshield, they saw a dead woman.

Police hauled up the car and traced it to the woman's husband. Meanwhile, examiners found contusions on the dead woman's head suggesting that she had been clubbed.

The husband said he had argued with his wife weeks earlier, in June. She had driven away upset into a foggy night, and he had not seen her since, he said. He maintained that she must have lost her bearings in the mist and plunged into the river. The police were skeptical.

For one thing, her head contusions did not seem to be caused by the accident. Also, investigators found that the husband had taken out an insurance policy on his wife's life. Later he had pawned her jewelry. In addition, neighbors disputed his claim that she had disappeared a few weeks earlier, in June--they had not seen her for months.

Police believed he was lying. But the cold water had preserved the woman's body, making it difficult to determine the date of death.

Finally the investigators spotted a clue: Insect pupal cocoons and larval cases were attached to' the car's fenders. The police sent the specimens to Michigan State University entomologist Richard Merritt, a specialist in aquatic insects.

Although the insects inside the cocoons had already flown away, Merritt recognized the signs of black flies, midges and caddisflies. From the black fly cocoons, Merritt could work out the approximate date the car had entered the water.

Black flies spend the winter as larvae in water. In spring, the larvae weave cocoons around themselves, cemented to a streambed rock or some other solid base--in this case, a sunken car. Inside a cocoon, a larva develops into an adult, with wings and mature sexual organs. Then it emerges and flies off to mate and continue the cycle.

"Because I knew these species pupate in late April and May, I knew the car must have gone into the river no later than that," says Merritt. "If it had gone into the river in June, as the husband claimed, it would not have had the cocoons on its fenders."

On April 16, 1990, in the courthouse in White Cloud, Michigan, the suspect stood trial. The prosecutor presented evidence that the man had clubbed his wife to death and sent her body careening into the river in the car to fake an accident. Richard Merritt testified that the insect cocoons proved the car had entered the river no later than April, not June as the husband claimed. The jury decided the man was lying. The verdict was "guilty."

As Merritt puts it: "That man was convicted of murder, based partly on the life cycle of an insect."

The Case of the Scrambled Bones

Glyde Earl Meek is currently on the FBI's "wanted" list for stabbing his girlfriend's wealthy parents to death on January 16, 1985, in Jackson, New Hampshire. But the chances for an arrest are slim. According to anthropologist William Maples, of the University of Florida in Gainesville, "If the FBI wants to arrest Meek, he's here in my office, on a shelf."

Not all of Meek, of course. Just his bones. They arrived jumbled; in a bag.

In January 1985, the owner of a farm 15 miles north of Gainesville telephoned the county sheriff. Someone had left a car in his plowed field, the farmer reported. Also, he said, an old shack in the field had unaccountably burned to the ground.

In the shack's ashes, the sheriff's deputies found two human skeletons, side by side. One was male, one female. Deputies also found empty gasoline cans, charcoal briquettes and a sawed-off shotgun. In the car, they found burglary tools, neatly folded male and female clothing and an eight-page, hand-written suicide note, signed by Glyde Earl Meek.

Police records revealed that Meek was a 49-year-old drifter and thief, who had repeatedly served time in jail. Meek's note said he and his 21-year-old girlfriend, Page Jennings of Jackson, New Hampshire, had decided to die together. But New Hampshire authorities thought that the bones might be somebody else's and that Meek had faked his own death.

The Alachua County sheriff's office, in Florida, had the skeletons photographed. Then an inexperienced investigator from the medical examiner's office gathered up the burned bones, along with a dog skeleton also lying in the ashes, and jumbled them together in a body bag.

The next day, the medical examiner's office called William Maples, who had been out of town. He had once studied primates in Kenya, but now he specialized in forensic anthropology, helping criminal justice agencies nationwide. The medical examiner gave him the bag of bones.

"It was the world's biggest, most macabre jigsaw puzzle," says Maples. The bag contained 10,000 burned bone fragments, dog and human. Now that they were broken and jumbled, it was unclear which bones were the man's, the woman's and the dog's. Meanwhile, the case had developed a new twist.

The Florida police had learned that ten days earlier firemen in Jackson, New Hampshire, had put out an arson fire at a ski lodge. The lodge belonged to Page Jennings' parents. Inside, the firemen found the well-to-do owners' bodies. They had been stripped, tied to chairs and stabbed. New Hampshire police had a suspect for both the arson and the murders: Glyde Earl Meek.

Meek had met Page Jennings, a college student, at an Alaskan lodge where they both worked one summer. Her parents did not approve of Meek. She brought Meek to New Hampshire anyway. After a bitter argument with her parents, Page drove with Meek to Florida to visit her brother, who worked at a Gainesville newspaper. But Meek was disruptive, and the brother told them to leave. Page Jennings was never again seen alive.

Meek checked into a Gainesville motel, apparently alone. The next day he drove to New Hampshire, leaving a trail of charge slips and sightings by hotel and gas station workers. Police placed him in New England when Page's parents were murdered because a pawnbroker in Portland, Maine, said a man who looked like Meek twice tried to pawn jewels he claimed were his daughter's. First he said she had died in a skiing accident. Then he said she was killed in an auto crash, which made the pawnbroker suspicious.

New Hampshire had issued a warrant for Meek's arrest when the two burned skeletons and the suicide note turned up in Florida. It was up to Bill Maples to prove that the jumble of bones in his laboratory had once been Glyde Earl Meek and Page Jennings.

Within six months, Maples and his students had pieced together key portions of the skeletons. He then took X-rays of the reconstructed bones. "When I compared these with medical and dental X-rays taken of Meek and Jennings when they were alive, I was sure the skeletons were theirs," says Maples. But he wanted to be certain. So he and his students spent another year gluing together additional bone fragments.

"Then I invited the Alachua County, Florida, sheriff and medical examiner to come to my office so I could show them the evidence," says Maples. The forensic anthropologist's careful work convinced the officials that the two people burned in the shack were Meek and Jennings. On October 17, 1986, Florida formally issued death certificates for Meek and Jennings. But New Hampshire officials refused to believe it. "I became somewhat ticked off at that point," says Maples.

He armed himself with a new technology, video superimposition: two video cameras that blend their two images on a single screen. With this, he could superimpose an X-ray of the reconstructed skeletal pieces over a medical X-ray of the bone taken when the person was alive, to see how well they matched. The results were riveting.

On the screen, Maples focused a chiropractor's X-ray of Meek's first right rib. Then, over it, he superimposed an image of the man's right rib, taken from the burned shack. Ossification, notches, areas of density--every detail matched. Next he put Page Jennings' dental X-rays on the screen. Her pulp cavities were unusually shaped. Over the dental X-ray, Maples superimposed the woman's jaw bone from the burned shack. The unusual pulp cavities matched down to the tiniest detail. Other superimposed X-rays showed the same results--they all matched.

Maples also had found parts of Meek's jaw, and X-ray analysis confirmed that a white dot on the bone was lead. "In the words of the game, he ate his gun," say: Maples. "He shot himself."

Just in case, Glyde Earl Meek remains on the wanted list. But nobody is looking hard for him. As Bill Maples wryly notes, whenever the FBI or New Hampshire officials want to close the case, he'll take Glyde Earl off the shelf and turn him in.

The case of the Seedy Blanket

Botanist David Hall received a call at his University of Florida office in Gainesville from the district attorney's office in Orlando: A teenage girl had reported being abducted and raped. But the evidence was botanical.

As investigators pieced the story together, a man had been cruising the Orlando streets, trying to pick up young women. Finally he abducted a girl at knife point. He drove her to a damp, wooded area outside town and raped her on a blanket. Then he drove her back to the city and released her. Throughout the abduction, the man had a baby with him in the car.

At first, the terrified girl told no one. However, two days later, as she walked along a street, she saw her abductor drive by. She took down his license number, then, with her mother, went to the police.

The police traced the license to a married man who had a baby matching the girl's description of the infant in the car. The suspect claimed he was home the night of the rape.

When investigators found the crime scene, a wooded wetland beside a busy road, they discovered a tissue the girl said she had used to wipe away tears. They also saw plants crushed where she said the blanket had been. In the suspect's car, the police found a blanket with seeds, twigs and bits of leaf stuck to it. He claimed the plant material had come from his lawn and a park where he had used the blanket for family picnics. The case came down to the victim's word against his.

Police decided on a long shot. They called botanist David Hall. Could he examine the plant litter on the blanket and determine where it originated? Hall promised to try.

"I got the blanket from the crime lab and discovered pieces of six plant species on it, jillions of bits of sandspurs, creeping beggarweed, Spanish moss, beard grass, dog fennel and beak-rush," says Hall. "They're all common, but finding them together is rare."

Hall visited the woods where the girl said she was raped. Three species on the blanket--beard grass, dog fennel and beak-rush--matched plants growing at the rape site. And their growth stage matched that of the site's plants on the date of the rape. Then Hall checked the suspect's lawn and the park where the man said he had used the blanket. The plant species found on the blanket did not match the park's or lawn's flora. "Beard grass, dog fennel, and beak-rush all need a wet habitat to thrive," says Hall. Neither the park nor lawn was watery. But the rape site was a wetland.

At the trial, in Orlando in 1983, the defendant's attorney asked Hall if the same species of weeds found at the rape site could not also have blown onto the lawn and park where the accused man said he used the blanket. "They could, but not enough of them to produce the thousands of pieces found on the blanket," Hall said. In addition, he testified, the growth stages of the plants on the blanket and at the rape site matched. And to produce the fragments on the blanket, the plants would have to be growing abundantly and 3- to 9-feet high. The chances of such plants blowing in such large numbers onto the lawn or park were nil.

Based on the "testimony" of the seedy blanket, the jury said "guilty." The rapist is currently in a Florida prison, serving 44 years for sexual battery and 44 years for kidnapping.