A society of solid members. To save endangered trees, an ecology initiative ahead of its time.

An oak tree more than 36 feet around? That's right, and this gnarled, serpentine wonder of Lewisburg at Mandeville, La., is noteworthy not only for its girth, but for the office it holds. The ``Seven Sisters,'' named for the multiple sub-trunks that writhe out of its main bulk, is ``president'' of the Live Oak Society. That makes it first among the 2,000 or so ``members'' of the society scattered in backyards and along roadsides from coast to coast. It also makes it very probably the largest oak tree in the United States, for the presidency always goes to the member that stretches the tape measure farthest.

The Live Oak Society was the special project of Dr. Edwin Lewis Stephens, former president of the University of Southwestern Louisiana in Lafayette. As Dr. Stephens and his wife traveled their region in the mid-1930s, it struck them that the magnificent live oaks of the area -- trees that had graced antebellum mansions and witnessed the first French voyagers rafting down the Mississippi -- were under serious assault. Many were being painted halfway up with lime (an act of defacement which was then thought to benefit the trees); others were being festooned with advertising placards.

And even these were a remnant. The nation's once extensive live oak forests had long since vanished before the axes of men seeking prime wood for shipbuilding. Early laws had been passed to protect remaining trees, but poachers continued to thin the stands of oak.

The Stephenses pondered the situation and came up with an effective, if whimsical solution: a society that would honor and protect the trees through enrollment in an exclusive club -- once dubbed the ``most exclusive'' in the country by ``Ripley's Believe It or Not'' because only trees can belong -- and flatter their owners in the bargain.

All that is required of the owners -- as stipulated 50 years ago by Dr. Stephens -- is a promise never to whitewash the trees or hang signs on them. In return, owners get the satisfaction of having a duly registered landmark right in their own back, or front, yard.

Dr. Stephens also asked a nominal dues of 15 acorns a year, a request that lapsed over the years as membership grew to more than 1,000 and the acorn treasury burst at its seams.

Of course, the monstrous oaks need some human assistance in running their society -- a coordinating role that lapsed for a while after Dr. Stephens's death.But through the efforts of his sisters the responsibility of screening and accepting new arboreal members came to rest with the Garden Club Federation of Louisiana in 1964. Over the past 20 years the federation's president has seen to it that the venerable live oaks have a human chairman to guide their affairs.

The current chairman, recently reappointed for another two-year stint, is Mrs. Louis Pfister of Metairie, La., a suburb of New Orleans. ``I'm it,'' says Mrs. Pfister cheerily, ``the only human being that's a member of the Live Oak Society.'' A widow who lives alone, she finds the chairmanship often entertaining and sometimes demanding. It's not unusual fo her to get two or three long-distance calls a week from people making inquiries for their favorite live oak, and she has mailed out as many as a dozen application forms at a time, particularly after such events as the regional Deep South garden club convention she recently attended in Huntsville, Ala.

She manned a Live Oak Society booth there, extolling such oaken virtues as feeding squirrels, sheltering birds, and providing mulch. She even had a live oak sapling on hand which, alas, didn't thrive in the convention hall. Mrs. Pfister, ever resourceful, made the best of it with a sign that read, ``Don't let this happen to your live oak -- join now!''

She says she is always heartened by the depth of feeling inquirers have for their oaks. ``They love their trees,'' she says. And if the oaks are ever threatened, owners call up ``desperately,'' asking what can be done to stop the construction of a new road or shopping center. ``They think I'm a lawyer, and I'm just a little housewife,'' Mrs. Pfister chuckles.

Little housewife or not, she gives callers sound advice: Get in touch with your legislators; try to get recognition and protection for Live Oak Society members. Louisiana's lawmakers, she says, are even now being presented with proposals to make a special effort to preserve live oaks registered with the society. But if the distress call concerns a neighbor's desire to whack off an encroaching limb, concedes Mrs. Pfister, there's not much to be done. The law enshrines the neighbor's right to control whatever is within the boundaries of his or her own property.

The application for membership in the Live Oak Society, by the way, asks for such vital statistics as a tree's girth (17 feet around is the minimum) and its name. Most owners, notes Mrs. Pfister, seem to get a kick out of naming their trees. Tags range from the obvious (``That Ole Oak Tree'') to the anthropomorphic (the names of wives, children, or forebears), to the mystifying (``The Coffee Tree''). And some trees become memorials. The state garden club headquarters in Lecompte, La., has two massive oaks on its grounds named in honor of society founder Stephens and Mrs. Harry Brown, one of the people instrumental in reviving the society after Dr. Stephens's passing.

There's also space on the application to record such relevant information as the tree's place in family history. Mrs. Pfister says that a number of people have found mentions of trees in a family Bible or other ancestral record -- often hinting at the age of the tree.

And the age of a live oak can be impressive indeed. Generally, says the society's chairman, a tree with a girth of 8 to 16 feet is thought to be at least 75 years old. Sixteen feet and up indicates a century or more. She recalls a hurricane a few years ago that so badly damaged an ancient oak at Avery Island, up the Gulf coast from New Orleans, that the state foresters had to cut it down. When the growth rings on the mammoth cross section were examined, experts estimated the tree's age at 1,000 years. The average age of society members is 400.

For natural history buffs, clearly, as well as for general lovers of nature, the Live Oak Society shoulders no small responsibility: its members are among the oldest living things on the globe. Mrs. Pfister, a garden club ``activist'' for over 30 years, gets obvious enjoyment from helping to look after that august membership -- a membership that, in her words, ``stretches from Texas all the way east to Louisiana and Mississippi, then up the Atlantic coast to North Carolina, with a few in Kentucky and two in California.''

Her day is made, one suspects, when, as once happened, someone from as far away as London contacts her. The man in question owned land on an island off the Carolina coast. He had heard about the Live Oak Society from one source or another and wanted one of his prized oaks registered.

For anyone else who may know of a deserving live oak, Mrs. Pfister's address is: 3712 West Metairie Avenue North, Metairie, La. 70001.