Cabbage Key: a jungly isle that has the feeling of old Florida

They grow scarcer by the year, those treasured little places at the end of the road - the unknown country inn, the unsung cafe. So the heart soars, the feet do a little dance, when you find a Cabbage Key.

Rob and Phyllis Wells found Cabbage Key in the mid-1970s, a jungly green islet off the west coast of Florida about halfway between Venice and Fort Myers. They and their two children, an American Family Robinson if you will, are the only full-time residents of the 100-acre key. But they are not alone with the ospreys, hawks, and occasional Florida panthers. They run a restaurant and little inn in a lovely 1930s clapboard house, a favorite stop for sailors and genial drifters all along the coast.

It wasn't so long ago that the Gulf Coast specialized in such retreats. But eventually the highways and shopping malls wormed into every cove and inlet. On a recent expedition from Tarpon Springs clear down to Everglades City, I found myself on sleepy Gasparilla Island - not an island really, because it is connected by a bridge - wondering if I had come to one of the last holdouts. Then a man from a local resort set me straight: ''Cabbage Key is what you want. If the seas calm down, I'll run you out there tomorrow. All there is is a six-room inn and a restaurant. Great stone crabs and cheeseburgers. Jimmy Buffett likes to stop off there with his boat.''

Even if I had known that E. G. Marshall, Roger Mudd, and Ed McMahon had also been to Cabbage Key, I wouldn't have been swayed off course. But the weather was worse the next day, and I couldn't wait it out. I had an appointment with a shelling beach just down the coast at Sanibel-Captiva. But first I called Cabbage Key and got Rob Wells on a crackling connection.

''You have to come out,'' said a friendly Southern voice. ''Even if you stay only for lunch. The inn was built by Mary Roberts Rinehart, the playwright and mystery writer, between 1927 and 1938. It was her winter home for years. You can charter a boat from Captiva.''

Next morning I was skimming northward under a gray but glinting sky in Blue Runner III, a shallow-water outboard piloted by Herb Purdy. The boat was new and racy, but Mr. Purdy was straight out of a 1940s Hemingway-Florida Keys story made into a Hollywood movie with Humphrey Bogart. The crusty-looking skipper, who works out of the South Seas Plantation marina on Captiva, normally charters to fishermen and shellers not content with the Sanibel-Captiva shores.

We raced along with two porpoises - Herb said they can do 60 miles per hour and can handle most sharks - and suddenly we were pulling up to a tufted green isle with a shingled dockhouse in front. I climbed a path to the main house, which sits on a grassy, ancient Indian mound 38 feet high, and swung open the very screen door I had envisioned. In the darkened room, Rob Wells - tall, husky , blond - was monkeying with a radiophone, trying to call the mainland. He came out a few minutes later with a Cabbage Key scrapbook bearing a few local clippings, and we sat on the screened veranda looking down on the dock.

Mr. Wells was admissions director of High Point College, N.C., and his wife was an elementary schoolteacher when they decided to bank their future on something less predictable, more exotic. He stumbled onto Cabbage Key on a scouting trip, and in 1976 they bought the island and its handful of buildings, water tower, and decaying but still salvageable inn.

''The people who built this house were very sophisticated,'' he said, referring to Mary Roberts Rinehart and her son Alan. ''It has a solar-energy system, six working fireplaces, five porches - and the wood shingles on the roof are original, they've stood up to a lot of hurricanes.''

The six guest rooms ($26 a night) are spacious and pine-paneled, with slat shades, rocking chairs, huge zinc tubs, and stone fireplaces. Most visitors, though, arrive with their own floating homes - commercial mullet fishermen, shrimpers, yachtsmen, and tugboat captains from as far away as Louisiana. Mr. Wells has 25 boat slips, and he charges a dockage fee of 35 cents a foot.

Rob Wells took me on a tour of his 10-acre world in his favorite sedan - a golf cart. He pointed to an osprey nest high in a tree and another on a weathered water tower beside the house. ''We also see big red-shouldered hawks - they eat rats and snakes. Wild boars swim over from the other keys, and we've seen Florida panther tracks.''

We puttered down a jungly trail that Mr. Wells has laid out to give visitors a closer look at the habitat and something to do between meals. Soon we were enveloped in tangles of banyan, seagrape, moss-hung oaks, and cabbage palm - for which the key is named. It was dark and a little spooky, just the place for plotting pirates. Nearby Gasparilla Island had indeed been staked out by the brothers Gaspar, Jose and Leon, who plundered passing vessels. ''Pirates came to Cabbage Key,'' said Rob Wells, ''to use the Indian mounds as lookouts.''

We had lunch on the rear screened porch, dining on the vaunted cheeseburgers and chilled key-lime pie. It was then that Herb Purdy began to talk of other keys and isles, a soliloquy that lasted all the way back to the marina at Captiva. He mentioned Cayo Costa and Johnson Shoals, beautiful, lonely keys with long sandy beaches that yield exotic shells no longer found on Sanibel and Captiva. Once again I could feel my feet doing that little dance.

If you want to get to Cabbage Key on your own, you can rent a motor boat or sailboat from Trispar Marine Charters, Captiva Island, Fla. 33924, phone (813) 472-5111. The Boca Grande Club on Gasparilla Island can set up the 25-minute trip across Boca Grande Pass. Phone: (813) 964-2211. Or Rob Wells himself may pick you up on the mainland. Write Cabbage Key, P.O. Box 489, Bokeelia, Fla. Phone: (813) 283-2278.