MOUNT DESERT ISLAND — Glen Mittelhauser, one of Maine’s leading naturalists, stands in the middle of plot 216 in the Bass Harbor Salt Marsh, armed with a notebook and a Garmin global positioning system device. To the uninformed, this 25-by-25-foot plot and all the others look about the same: tall, bright grasses that don’t mind having their feet in the damp. If it were a jigsaw puzzle, it would try the patience of a saint. For Mittlehauser the salt marsh is well-varied territory, albeit uncharted with proper specificity.

He is there to fix this, to create a map for the future. As he collects his data he does so with the botanist of 50 years from now in mind.

“What tidbit can I get in there for them?” he said. In his own field work he’s been grateful for the naturalists of the past who used even something as basic as a place name to note where they found a species. From a century ago, those are helpful clues. But using GPS and a careful grid system as he inventories the plants of this salt marsh, Mittelhauser can send the botanist of the future to an exact location to see just how the natural world has changed as a result of development, climate change or some other factor.

It would be a challenge to make a complete list of all of Mittelhauser’s lists, but in the 30 plus years since Mittelhauser arrived in Maine to attend the College of the Atlantic, he’s inventoried Acadia’s plants in a book called “The Plants of Acadia,” the sedges of Maine (flowering plants different from grasses and rushes) in another book and Isle au Haut’s winter population of nesting Harlequin ducks. This August marks the release “The Plants of Baxter State Park,” co-authored with botanist Alison Dibble and six others, which contains the first complete inventory of the park’s 857 types of plants, information gathered over five years.

Glen Mittelhauser, founder of the Maine Natural History Observatory and author of guides to plants and birds in Maine, in his element.

The Bass Harbor Salt Marsh field work he finished this month is a contract job for Acadia National Park. The park hired Mittelhauser to assess how much sweet grass – a key component in Native American basketmaking – grows in the marsh, which lies partly within the park’s boundaries.

“I asked, ‘Should I map all the species while I’m in there?’ ” Mittelhauser said. “And they said, ‘Go for it.’ ”

One gets the sense that among Maine’s wildlife experts and ecologists, few would turn down a chance to have Mittelhauser, a botanist and birder who runs a nonprofit called the Maine Natural History Observatory, take a closer look.

“He’s a consummate naturalist,” said Brad Allen, a wildlife biologist with Maine’s Department of Inland Fisheries & Wildlife. “We pull him in every chance we get.”

“He has really had an impact on natural history investigations along the coast of Maine,” said Judy Hazen Connery, who gave him his first job at Acadia after he left the College of the Atlantic.

AN EVEN KEEL

Allen met Mittelhauser in the late 1980s, when he was finishing his degree at the College of the Atlantic. The young man, who had grown up in Old Saybrook, Connecticut, was studying Harlequin ducks, which winter in a few areas of coastal Maine, including Isle au Haut.

“I tried to follow his (butt) across Isle au Haut,” Allen said. “He would do like a 10-mile survey hiking all over these the slippery, icy rocks in the middle of the winter.” Or in a small boat. “With just a heavy sweater and this little life jacket,” Allen said. You can almost hear him shaking his head on the other end of the phone line.

There came a point when Inland Fisheries & Wildlife was considering closing the hunting season on Harlequin ducks, and Allen needed numbers for the nesting populations. He knew the twentysomething would have the most accurate counts of the birds. “I had to go to Glen to find out,” Allen remembered. Allen eventually encouraged Mittelhauser to go on to graduate work at the University of Maine in Orono, where he received a master’s degree in zoology in 2000. They’ve worked together countless times since that first encounter.

“We have worked with him under ungodly weather conditions,” Allen said. “And there’s never been too many mosquitoes or too big a wave. I’ve never heard him complain.”

Or get mad, he added. “He is just so even-keeled.”

Mittelhauser, at the Bass Harbor Salt Marsh, is a graduate of the College of the Atlantic who has devoted his career to Maine’s plants.

The nautical term is apropos. By the time Mittelhauser was nine, or maybe 10, he can’t remember exactly when, he had a 10-foot sailboat with a mainsail, jib and centerboard and was let loose in the neighborhood cove by himself. “I sailed that thing daily for years,” he said. Mostly alone, and as he got more experienced, farther afield. His parents took the family cruising in the summers, and his father built dinghies in his spare time.

When Mittelhauser was 12 or 13, he told his parents he wanted to be the youngest person ever to sail alone across the Atlantic. “That freaked them out,” he remembered. “They hemmed and hawed and said, ‘Why don’t you build a boat?’ What I heard was, ‘Why don’t you build a boat to sail across the Atlantic?’ ”

He picked out a 22-foot boat, an amibitious enough project to take him five years to build. His father was able to help only with the first part of the building process. “He got sick and passed away partway through it,” Mittelhauser said. He finished the boat alone and named it Scrimshaw; back then he was in the midst of a serious love affair with whales. He never made it across the Atlantic. But being outdoors and isolated always held intrigue for Mittelhauser.

He and high school friends began planning during their junior year to graduate early so they’d have time to hike the Appalachian Trail together before college (they walked about 1,000 miles of the 2,200-mile trail). And it was a hike around Mount Desert Island that convinced him that the College of the Atlantic, a school suggested to him by an English teacher and sailing coach, was the place for him.

His plan, when he arrived at the school, was to study whales. But no whale-related courses were offered that first semester, so he began studying birds and plants.

“I’ve never been able to decide if I’m a birder or a botanist,” he said.

BEING A LIST MAKER

Regardless, he is a list maker. He said his children, Pepin and Celeste, who are both in college, he at the College of the Atlantic, she at the University of Southern Maine, do wicked imitations of what going for a hike with him is like. Gather up the gear, including notebooks, camera and various supplies, walk five feet, spot something, put down the gear to examine and make note of it. Pick up the gear, repeat. And again.

Glen Mittelhauser walks through a patch of marsh grass in South Thomaston.

You might ask, does it really matter whether we know that there are 857 plant species in Baxter State Park? Wouldn’t 851 be thorough enough? Not quite.

“What it does is give us an understanding of what we are protecting,” said Jean Hoekwater, Baxter’s park naturalist. “It is our job to protect the natural resources and if you really don’t know all the components, that can be more difficult. Furthermore you can’t measure change.”

Knowing exactly what they’ve got will help Baxter officials set policy and site new trails and use areas.

No comprehensive early inventory of Baxter’s plants existed, which Mittelhauser found intriguing. He had to do a lot of historical leg work before setting out, visiting herbariums that had old samples from Baxter. “He established a history,” Hoekwater said.

Naturally, Mittelhauser and Dibble couldn’t count every species in the park themselves. A group of about 50 volunteers, including both trained botanists and novices from Friends of Baxter State Park, a citizen initiative to support the park’s mission of preservation, helped over the course of those five years. They came in for a half a dozen weeklong stints in remote corners of the park every year. Sometimes the groups, six at a time, stayed in crew housing (lean-tos mostly) and sometimes they camped. They bushwhacked, used canoes and visited places that few, if any park visitors, ever see. It wasn’t glamping, and it required a leader who could motivate a crowd.

“Definitely he did the lion’s share of recruiting and training the volunteers,” Hoewater said. “That’s all Glen.”

That group, Hoekwater said, represents a less tangible but no less important part of the research project. “He really brought along a whole group who are passionate about the plants in the park and are able to help us with future studies.”

On top of this, he made quicker trips on his own “when he just wanted to check something.” The project and resulting book – sales of which will benefit the park – represents a major accomplishment, Hoekwater said.

“If you’re talking to Glen about it, he is probably understating it,” she added.

UNDERSTATED LEADER

That, it seems, would be the Mittelhauser way. He does say he was “blown away” when there turned out to be 857 plants. “I was thinking that the total fauna was going to be 500 to 600,” he said. But he sounds far too solid on his feet to be in danger of blowing away.

Allen calls him humble.

Mittelhauser holds the mainly coastal grass species Juncus gerardii. Identifying species helps scientists measure change, among other things.

“He has an insatiable appetite for learning about natural history,” said Judy Hazen Connery, who hired and supervised Mittelhauser at Acadia, where he worked for a decade seasonally in resource management before setting out on his own. Back then he was “really shy, really quiet,” and when she brought him in to work an island inventory project – looking at the vegetation on 10 islands near and offshore that were within Acadia’s boundary – she admits that she initially worried about his leadership skills. The teams along for each two-week long inventory needed direction.

“We needed a leader who was kind of gregarious and put everyone at ease and would be a dynamic teacher,” Connery said. “And Glen is so quiet.”

But “time and and again, within about an hour Glen would have them listening intently for every word he spoke and they loved him.”

It was a good lesson for her, she added. “That you shouldn’t judge a book by its cover or go in with preconceived notions.”

GRASSES ARE GROWING ON ME

“Sedges have edges,” Mittelhauser said, squatting in the marsh to find a sample to explain the difference among the three kinds of Graminoids. That’s a word that describes grasses and grasslike plants, one of many big words that need repeating and spelling in an afternoon on the marsh with him. “I have trouble with common names,” he apologizes.

“Rushes are round,” he said, bending one out to be felt. “And grasses have joints, all the way to the ground.”

“I’m partial to sedges,” he said. “Grasses are growing on me.”

This is good, because his next project is a book on the grasses of Maine. He’s working with three other botanists and still figuring out the funding.

In 2003, Mittelhauser established the Maine Natural History Observatory, a nonprofit with a mission to further the understanding of the states flora and fauna. It’s based out of Gouldsboro, where he and his family live on 160 acres purchased for the price of “a third of an acre on Mount Desert.” He works with another botanist and a pair of half-time “data geeks” who help him crunch numbers. It’s a freelance kind of life that involves writing a lot of grants. Is he particularly good at that? He gave a quiet laugh.

“I have never run out of work in 10 years so I guess I must be tolerable at them.”

Early in his career, he struggled with whether to get a job with benefits and security versus the semi-freelance life he’s chosen. He jokes that he’s made himself unemployable. But that’s OK. In the winter, in between grant writing and the joy of crunching numbers (yes, he used the word joy. “I’m geeky that way.”) he can play a Virtual Regatta, an online sailing game that takes him around the world on the screen. And in the warm months, he can hop on his sailboat, a 19-foot Drascombe lugger made in 1964, the year he was born, and go exploring the coast, keeping his eye out for breeding gulls or purple sandpipers. Sometimes the work is unpaid or barely paid and steered simply by curiosity.

“I like pursuing projects that I think are worthwhile and putting my time in on those projects, even if it does mean taking a big pay cut to do that.”

“I’m happy,” he addded. “And that is worth a lot.”